Title: | Advanced Graphics and Image-Processing in R |
---|---|
Description: | Bindings to 'ImageMagick': the most comprehensive open-source image processing library available. Supports many common formats (png, jpeg, tiff, pdf, etc) and manipulations (rotate, scale, crop, trim, flip, blur, etc). All operations are vectorized via the Magick++ STL meaning they operate either on a single frame or a series of frames for working with layers, collages, or animation. In RStudio images are automatically previewed when printed to the console, resulting in an interactive editing environment. The latest version of the package includes a native graphics device for creating in-memory graphics or drawing onto images using pixel coordinates. |
Authors: | Jeroen Ooms [aut, cre] |
Maintainer: | Jeroen Ooms <[email protected]> |
License: | MIT + file LICENSE |
Version: | 2.8.5 |
Built: | 2024-11-24 06:56:23 UTC |
Source: | CRAN |
The magick
package for graphics and image processing in R. Important resources:
R introduction vignette: getting started
Magick++ API and Magick++ STL detailed descriptions of methods and parameters
Documentation is split into the following pages:
analysis - metrics and calculations: compare
, fft
animation - manipulate or combine multiple frames: animate
,
morph
, mosaic
, montage
, average
, append
, apply
attributes - image properties: comment
, info
color - contrast, brightness, colors: modulate
, quantize
, map
, transparent
,
background
, colorize
, contrast
, normalize
, enhance
, equalize
, median
composite - advanced joining: composite
, border
, frame
device - creating graphics and drawing on images
editing - basic image IO: read
, write
, convert
, join
, display
, brose
effects - fun effects: despecle
, reducenoise
, noise
, blur
, charcoal
,
edge
, oilpaint
, emboss
, implode
, negate
geometry - specify points, areas and sizes using geometry syntax
options - list option types and values supported in your version of ImageMagick
painting - flood fill and annotating text
transform - shape operations: trim
, chop
, rotate
, resize
, scale
, sample
crop
, flip
, flop
, deskew
, page
Other image:
analysis
,
animation
,
attributes()
,
color
,
composite
,
defines
,
device
,
edges
,
editing
,
effects()
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
Functions for image calculations and analysis. This part of the package needs more work.
image_compare(image, reference_image, metric = "", fuzz = 0) image_compare_dist(image, reference_image, metric = "", fuzz = 0) image_fft(image)
image_compare(image, reference_image, metric = "", fuzz = 0) image_compare_dist(image, reference_image, metric = "", fuzz = 0) image_fft(image)
image |
magick image object returned by |
reference_image |
another image to compare to |
metric |
string with a metric
from metric_types() such as |
fuzz |
relative color distance (value between 0 and 100) to be considered similar in the filling algorithm |
For details see Image++ documentation. Short descriptions:
image_compare calculates a metric by comparing image with a reference image.
image_fft returns Discrete Fourier Transform (DFT) of the image as a magnitude / phase image pair. I wish I knew what this means.
Here image_compare()
is vectorized over the first argument and returns the diff image
with the calculated distortion value as an attribute.
Other image:
_index_
,
animation
,
attributes()
,
color
,
composite
,
defines
,
device
,
edges
,
editing
,
effects()
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
out1 <- image_blur(logo, 3) out2 <- image_oilpaint(logo, 3) input <- c(logo, out1, out2, logo) if(magick_config()$version >= "6.8.7"){ diff_img <- image_compare(input, logo, metric = "AE") attributes(diff_img) }
out1 <- image_blur(logo, 3) out2 <- image_oilpaint(logo, 3) input <- c(logo, out1, out2, logo) if(magick_config()$version >= "6.8.7"){ diff_img <- image_compare(input, logo, metric = "AE") attributes(diff_img) }
Operations to manipulate or combine multiple frames of an image. Details below.
image_animate( image, fps = 10, delay = NULL, loop = 0, dispose = c("background", "previous", "none"), optimize = FALSE ) image_coalesce(image) image_morph(image, frames = 8) image_mosaic(image, operator = NULL) image_flatten(image, operator = NULL) image_average(image) image_append(image, stack = FALSE) image_apply(image, FUN, ...) image_montage( image, geometry = NULL, tile = NULL, gravity = "Center", bg = "white", shadow = FALSE )
image_animate( image, fps = 10, delay = NULL, loop = 0, dispose = c("background", "previous", "none"), optimize = FALSE ) image_coalesce(image) image_morph(image, frames = 8) image_mosaic(image, operator = NULL) image_flatten(image, operator = NULL) image_average(image) image_append(image, stack = FALSE) image_apply(image, FUN, ...) image_montage( image, geometry = NULL, tile = NULL, gravity = "Center", bg = "white", shadow = FALSE )
image |
magick image object returned by |
fps |
frames per second. Ignored if |
delay |
delay after each frame, in 1/100 seconds.
Must be length 1, or number of frames. If specified, then |
loop |
how many times to repeat the animation. Default is infinite. |
dispose |
a frame disposal method from dispose_types() |
optimize |
optimize the |
frames |
number of frames to use in output animation |
operator |
string with a composite operator from compose_types() |
stack |
place images top-to-bottom (TRUE) or left-to-right (FALSE) |
FUN |
a function to be called on each frame in the image |
... |
additional parameters for |
geometry |
a geometry string that defines the size the individual thumbnail images, and the spacing between them. |
tile |
a geometry string for example "4x5 with limits on how the tiled images are to be laid out on the final result. |
gravity |
a gravity direction, if the image is smaller than the frame, where in the frame is the image to be placed. |
bg |
a background color string |
shadow |
enable shadows between images |
For details see Magick++ STL documentation. Short descriptions:
image_animate coalesces frames by playing the sequence and converting to gif
format.
image_morph expands number of frames by interpolating intermediate frames to blend into each other when played as an animation.
image_mosaic inlays images to form a single coherent picture.
image_montage creates a composite image by combining frames.
image_flatten merges frames as layers into a single frame using a given operator.
image_average averages frames into single frame.
image_append stack images left-to-right (default) or top-to-bottom.
image_apply applies a function to each frame
The image_apply function calls an image function to each frame and joins
results back into a single image. Because most operations are already vectorized
this is often not needed. Note that FUN()
should return an image. To apply other
kinds of functions to image frames simply use lapply, vapply, etc.
Other image:
_index_
,
analysis
,
attributes()
,
color
,
composite
,
defines
,
device
,
edges
,
editing
,
effects()
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
# Combine images logo <- image_read("https://jeroen.github.io/images/Rlogo.png") oldlogo <- image_read("https://jeroen.github.io/images/Rlogo-old.png") # Create morphing animation both <- image_scale(c(oldlogo, logo), "400") image_average(image_crop(both)) image_animate(image_morph(both, 10)) # Create thumbnails from GIF banana <- image_read("https://jeroen.github.io/images/banana.gif") length(banana) image_average(banana) image_flatten(banana) image_append(banana) image_append(banana, stack = TRUE) # Append images together wizard <- image_read("wizard:") image_append(image_scale(c(image_append(banana[c(1,3)], stack = TRUE), wizard))) image_composite(banana, image_scale(logo, "300")) # Break down and combine frames front <- image_scale(banana, "300") background <- image_background(image_scale(logo, "400"), 'white') frames <- image_apply(front, function(x){image_composite(background, x, offset = "+70+30")}) image_animate(frames, fps = 10) # Simple 4x3 montage input <- rep(logo, 12) image_montage(input, geometry = 'x100+10+10', tile = '4x3', bg = 'pink', shadow = TRUE) # With varying frame size input <- c(wizard, wizard, logo, logo) image_montage(input, tile = '2x2', bg = 'pink', gravity = 'southwest')
# Combine images logo <- image_read("https://jeroen.github.io/images/Rlogo.png") oldlogo <- image_read("https://jeroen.github.io/images/Rlogo-old.png") # Create morphing animation both <- image_scale(c(oldlogo, logo), "400") image_average(image_crop(both)) image_animate(image_morph(both, 10)) # Create thumbnails from GIF banana <- image_read("https://jeroen.github.io/images/banana.gif") length(banana) image_average(banana) image_flatten(banana) image_append(banana) image_append(banana, stack = TRUE) # Append images together wizard <- image_read("wizard:") image_append(image_scale(c(image_append(banana[c(1,3)], stack = TRUE), wizard))) image_composite(banana, image_scale(logo, "300")) # Break down and combine frames front <- image_scale(banana, "300") background <- image_background(image_scale(logo, "400"), 'white') frames <- image_apply(front, function(x){image_composite(background, x, offset = "+70+30")}) image_animate(frames, fps = 10) # Simple 4x3 montage input <- rep(logo, 12) image_montage(input, geometry = 'x100+10+10', tile = '4x3', bg = 'pink', shadow = TRUE) # With varying frame size input <- c(wizard, wizard, logo, logo) image_montage(input, tile = '2x2', bg = 'pink', gravity = 'southwest')
Convert a Magick image to EBImage class. Note that EBImage only supports multi-frame images in greyscale.
as_EBImage(image)
as_EBImage(image)
image |
magick image object returned by |
Attributes are properties of the image that might be present on some images and might affect image manipulation methods.
image_comment(image, comment = NULL) image_info(image)
image_comment(image, comment = NULL) image_info(image)
image |
magick image object returned by |
comment |
string to set an image comment |
Each attribute can be get and set with the same function. The image_info()
function returns a data frame with some commonly used attributes.
Other image:
_index_
,
analysis
,
animation
,
color
,
composite
,
defines
,
device
,
edges
,
editing
,
effects()
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
This enables a addTaskCallback that automatically updates the viewer after the state of a magick graphics device has changed. This is enabled by default in RStudio.
autoviewer_enable() autoviewer_disable()
autoviewer_enable() autoviewer_disable()
# Only has effect in RStudio (or other GUI with a viewer): autoviewer_enable() img <- magick::image_graph() plot(1) abline(0, 1, col = "blue", lwd = 2, lty = "solid") abline(0.1, 1, col = "red", lwd = 3, lty = "dotted") autoviewer_disable() abline(0.2, 1, col = "green", lwd = 4, lty = "twodash") abline(0.3, 1, col = "black", lwd = 5, lty = "dotdash") autoviewer_enable() abline(0.4, 1, col = "purple", lwd = 6, lty = "dashed") abline(0.5, 1, col = "yellow", lwd = 7, lty = "longdash")
# Only has effect in RStudio (or other GUI with a viewer): autoviewer_enable() img <- magick::image_graph() plot(1) abline(0, 1, col = "blue", lwd = 2, lty = "solid") abline(0.1, 1, col = "red", lwd = 3, lty = "dotted") autoviewer_disable() abline(0.2, 1, col = "green", lwd = 4, lty = "twodash") abline(0.3, 1, col = "black", lwd = 5, lty = "dotdash") autoviewer_enable() abline(0.4, 1, col = "purple", lwd = 6, lty = "dashed") abline(0.5, 1, col = "yellow", lwd = 7, lty = "longdash")
ImageMagick can be configured to support various additional tool and formats via external libraries. These functions show which features ImageMagick supports on your system.
coder_info(format) magick_config() magick_set_seed(seed)
coder_info(format) magick_config() magick_set_seed(seed)
format |
image format such as |
seed |
integer with seed value to use |
Note that coder_info
raises an error for unsupported formats.
https://www.imagemagick.org/Magick++/CoderInfo.html
coder_info("png") coder_info("jpg") coder_info("pdf") coder_info("tiff") coder_info("gif") # Reproduce random image magick_set_seed(123) image_blank(200,200, pseudo_image = "plasma:fractal")
coder_info("png") coder_info("jpg") coder_info("pdf") coder_info("tiff") coder_info("gif") # Reproduce random image magick_set_seed(123) image_blank(200,200, pseudo_image = "plasma:fractal")
Functions to adjust contrast, brightness, colors of the image. Details below.
image_modulate(image, brightness = 100, saturation = 100, hue = 100) image_quantize( image, max = 256, colorspace = "rgb", dither = TRUE, treedepth = NULL ) image_map(image, map, dither = FALSE) image_ordered_dither(image, threshold_map) image_channel(image, channel = "lightness") image_separate(image, channel = "default") image_combine(image, colorspace = "sRGB", channel = "default") image_transparent(image, color, fuzz = 0) image_background(image, color, flatten = TRUE) image_colorize(image, opacity, color) image_contrast(image, sharpen = 1) image_normalize(image) image_enhance(image) image_equalize(image) image_median(image, radius = 1)
image_modulate(image, brightness = 100, saturation = 100, hue = 100) image_quantize( image, max = 256, colorspace = "rgb", dither = TRUE, treedepth = NULL ) image_map(image, map, dither = FALSE) image_ordered_dither(image, threshold_map) image_channel(image, channel = "lightness") image_separate(image, channel = "default") image_combine(image, colorspace = "sRGB", channel = "default") image_transparent(image, color, fuzz = 0) image_background(image, color, flatten = TRUE) image_colorize(image, opacity, color) image_contrast(image, sharpen = 1) image_normalize(image) image_enhance(image) image_equalize(image) image_median(image, radius = 1)
image |
magick image object returned by |
brightness |
modulation of brightness as percentage of the current value (100 for no change) |
saturation |
modulation of saturation as percentage of the current value (100 for no change) |
hue |
modulation of hue is an absolute rotation of -180 degrees to +180 degrees from the current position corresponding to an argument range of 0 to 200 (100 for no change) |
max |
preferred number of colors in the image. The actual number of colors in the image may be less than your request, but never more. |
colorspace |
string with a |
dither |
a boolean (defaults to |
treedepth |
depth of the quantization color classification tree. Values of 0 or 1 allow selection of the optimal tree depth for the color reduction algorithm. Values between 2 and 8 may be used to manually adjust the tree depth. |
map |
reference image to map colors from |
threshold_map |
A string giving the dithering pattern to use. See the ImageMagick documentation for possible values |
channel |
a string with a
channel from
channel_types for example |
color |
a valid color string such as
|
fuzz |
relative color distance (value between 0 and 100) to be considered similar in the filling algorithm |
flatten |
should image be flattened before writing? This also replaces transparency with background color. |
opacity |
percentage of opacity used for coloring |
sharpen |
enhance intensity differences in image |
radius |
replace each pixel with the median color in a circular neighborhood |
For details see Magick++ STL documentation. Short descriptions:
image_modulate adjusts brightness, saturation and hue of image relative to current.
image_quantize reduces number of unique colors in the image.
image_ordered_dither reduces number of unique colors using a dithering threshold map.
image_map replaces colors of image with the closest color from a reference image.
image_channel extracts a single channel from an image and returns as grayscale.
image_transparent sets pixels approximately matching given color to transparent.
image_background sets background color. When image is flattened, transparent pixels get background color.
image_colorize overlays a solid color frame using specified opacity.
image_contrast enhances intensity differences in image
image_normalize increases contrast by normalizing the pixel values to span the full range of colors
image_enhance tries to minimize noise
image_equalize equalizes using histogram equalization
image_median replaces each pixel with the median color in a circular neighborhood
Note that
colors are also determined by image properties
imagetype and
colorspace
which can be modified via image_convert()
.
Other image:
_index_
,
analysis
,
animation
,
attributes()
,
composite
,
defines
,
device
,
edges
,
editing
,
effects()
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
# manually adjust colors logo <- image_read("logo:") image_modulate(logo, brightness = 200) image_modulate(logo, saturation = 150) image_modulate(logo, hue = 200) # Reduce image to 10 different colors using various spaces image_quantize(logo, max = 10, colorspace = 'gray') image_quantize(logo, max = 10, colorspace = 'rgb') image_quantize(logo, max = 10, colorspace = 'cmyk') image_ordered_dither(logo, 'o8x8') # Change background color translogo <- image_transparent(logo, 'white') image_background(translogo, "pink", flatten = TRUE) # Compare to flood-fill method: image_fill(logo, "pink", fuzz = 20) # Other color tweaks image_colorize(logo, 50, "red") image_contrast(logo) image_normalize(logo) image_enhance(logo) image_equalize(logo) image_median(logo) # Alternate way to convert into black-white image_convert(logo, type = 'grayscale')
# manually adjust colors logo <- image_read("logo:") image_modulate(logo, brightness = 200) image_modulate(logo, saturation = 150) image_modulate(logo, hue = 200) # Reduce image to 10 different colors using various spaces image_quantize(logo, max = 10, colorspace = 'gray') image_quantize(logo, max = 10, colorspace = 'rgb') image_quantize(logo, max = 10, colorspace = 'cmyk') image_ordered_dither(logo, 'o8x8') # Change background color translogo <- image_transparent(logo, 'white') image_background(translogo, "pink", flatten = TRUE) # Compare to flood-fill method: image_fill(logo, "pink", fuzz = 20) # Other color tweaks image_colorize(logo, 50, "red") image_contrast(logo) image_normalize(logo) image_enhance(logo) image_equalize(logo) image_median(logo) # Alternate way to convert into black-white image_convert(logo, type = 'grayscale')
Similar to the ImageMagick composite
utility: compose an image on top of another one using a
CompositeOperator.
image_composite( image, composite_image, operator = "atop", offset = "+0+0", gravity = "northwest", compose_args = "" ) image_border(image, color = "lightgray", geometry = "10x10", operator = "copy") image_frame(image, color = "lightgray", geometry = "25x25+6+6") image_shadow_mask(image, geometry = "50x10+30+30") image_shadow( image, color = "black", bg = "none", geometry = "50x10+30+30", operator = "copy", offset = "+20+20" ) image_shade(image, azimuth = 30, elevation = 30, color = FALSE)
image_composite( image, composite_image, operator = "atop", offset = "+0+0", gravity = "northwest", compose_args = "" ) image_border(image, color = "lightgray", geometry = "10x10", operator = "copy") image_frame(image, color = "lightgray", geometry = "25x25+6+6") image_shadow_mask(image, geometry = "50x10+30+30") image_shadow( image, color = "black", bg = "none", geometry = "50x10+30+30", operator = "copy", offset = "+20+20" ) image_shade(image, azimuth = 30, elevation = 30, color = FALSE)
image |
magick image object returned by |
composite_image |
composition image |
operator |
string with a composite operator from compose_types() |
offset |
string with either a gravity_type or a geometry_point to set position of top image. |
gravity |
string with gravity value from gravity_types. |
compose_args |
additional arguments needed for some composite operations |
color |
Set to true to shade the red, green, and blue components of the image. |
geometry |
a geometry string
to set height and width of the border, e.g. |
bg |
background color |
azimuth |
position of light source |
elevation |
position of light source |
The image_composite
function is vectorized over both image arguments: if the first image has
n
frames and the second m
frames, the output image will contain n
* m
frames.
The image_border function creates a slightly larger solid color frame and then composes the original frame on top. The image_frame function is similar but has an additional feature to create a shadow effect on the border (which is really ugly).
Other image:
_index_
,
analysis
,
animation
,
attributes()
,
color
,
defines
,
device
,
edges
,
editing
,
effects()
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
# Compose images using one of many operators imlogo <- image_scale(image_read("logo:"), "x275") rlogo <- image_read("https://jeroen.github.io/images/Rlogo-old.png") # Standard is atop image_composite(imlogo, rlogo) # Same as 'blend 50' in the command line image_composite(imlogo, rlogo, operator = "blend", compose_args="50") # Offset can be geometry or gravity image_composite(logo, rose, offset = "+100+100") image_composite(logo, rose, gravity = "East") # Add a border frame around the image image_border(imlogo, "red", "10x10") image_frame(imlogo) image_shadow(imlogo) image_shade(imlogo)
# Compose images using one of many operators imlogo <- image_scale(image_read("logo:"), "x275") rlogo <- image_read("https://jeroen.github.io/images/Rlogo-old.png") # Standard is atop image_composite(imlogo, rlogo) # Same as 'blend 50' in the command line image_composite(imlogo, rlogo, operator = "blend", compose_args="50") # Offset can be geometry or gravity image_composite(logo, rose, offset = "+100+100") image_composite(logo, rose, gravity = "East") # Add a border frame around the image image_border(imlogo, "red", "10x10") image_frame(imlogo) image_shadow(imlogo) image_shade(imlogo)
So called 'defines' are properties that are passed along to external filters and libraries. Usually defines are used in image_read or image_write to control the image encoder/decoder, but you can also set these manually on the image object.
image_set_defines(image, defines)
image_set_defines(image, defines)
image |
magick image object returned by |
defines |
a named character vector with extra options to control reading.
These are the |
The defines values must be a character string, where the names contain
the defines keys. Each name must be of the format "enc:key" where the
first part is the encoder or filter to which the key is passed. For
example "png:...."
defines can control the encoding and decoding of
png images.
The image_set_defines function does not make a copy of the image, so the defined values remain in the image object until they are overwritten or unset.
Other image:
_index_
,
analysis
,
animation
,
attributes()
,
color
,
composite
,
device
,
edges
,
editing
,
effects()
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
# Write an image x <- image_read("https://jeroen.github.io/images/frink.png") image_write(x, "frink.png") # Pass some properties to PNG encoder defines <- c("png:compression-filter" = "1", "png:compression-level" = "0") image_set_defines(x, defines) image_write(x, "frink-uncompressed.png") # Unset properties defines[1:2] = NA image_set_defines(x, defines) image_write(x, "frink-final.png") # Compare size and cleanup file.info(c("frink.png", "frink-uncompressed.png", "frink-final.png")) unlink(c("frink.png", "frink-uncompressed.png", "frink-final.png"))
# Write an image x <- image_read("https://jeroen.github.io/images/frink.png") image_write(x, "frink.png") # Pass some properties to PNG encoder defines <- c("png:compression-filter" = "1", "png:compression-level" = "0") image_set_defines(x, defines) image_write(x, "frink-uncompressed.png") # Unset properties defines[1:2] = NA image_set_defines(x, defines) image_write(x, "frink-final.png") # Compare size and cleanup file.info(c("frink.png", "frink-uncompressed.png", "frink-final.png")) unlink(c("frink.png", "frink-uncompressed.png", "frink-final.png"))
Graphics device that produces a Magick image. Can either be used like a regular
device for making plots, or alternatively via image_draw
to open a device
which draws onto an existing image using pixel coordinates. The latter is vectorized,
i.e. drawing operations are applied to each frame in the image.
image_graph( width = 800, height = 600, bg = "white", pointsize = 12, res = 72, clip = TRUE, antialias = TRUE ) image_draw(image, pointsize = 12, res = 72, antialias = TRUE, ...) image_capture()
image_graph( width = 800, height = 600, bg = "white", pointsize = 12, res = 72, clip = TRUE, antialias = TRUE ) image_draw(image, pointsize = 12, res = 72, antialias = TRUE, ...) image_capture()
width |
in pixels |
height |
in pixels |
bg |
background color |
pointsize |
size of fonts |
res |
resolution in pixels |
clip |
enable clipping in the device. Because clipping can slow things down a lot, you can disable it if you don't need it. |
antialias |
TRUE/FALSE: enables anti-aliasing for text and strokes |
image |
an existing image on which to start drawing |
... |
additional device parameters passed to plot.window such as
|
The device is a relatively recent feature of the package. It should support all operations but there might still be small inaccuracies. Also it is a bit slower than some of the other devices, in particular for rendering text and clipping. Hopefully this can be optimized in the next version.
By default image_draw
sets all margins to 0 and uses graphics coordinates to
match image size in pixels (width x height) where (0,0)
is the top left corner.
Note that this means the y axis increases from top to bottom which is the opposite
of typical graphics coordinates. You can override all this by passing custom
xlim
, ylim
or mar
values to image_draw
.
The image_capture
function returns the current device as an image. This only
works if the current device is a magick device or supports dev.capture.
Other image:
_index_
,
analysis
,
animation
,
attributes()
,
color
,
composite
,
defines
,
edges
,
editing
,
effects()
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
# Regular image frink <- image_read("https://jeroen.github.io/images/frink.png") # Produce image using graphics device fig <- image_graph(res = 96) ggplot2::qplot(mpg, wt, data = mtcars, colour = cyl) dev.off() # Combine out <- image_composite(fig, frink, offset = "+70+30") print(out) # Or paint over an existing image img <- image_draw(frink) rect(20, 20, 200, 100, border = "red", lty = "dashed", lwd = 5) abline(h = 300, col = 'blue', lwd = '10', lty = "dotted") text(10, 250, "Hoiven-Glaven", family = "monospace", cex = 4, srt = 90) palette(rainbow(11, end = 0.9)) symbols(rep(200, 11), seq(0, 400, 40), circles = runif(11, 5, 35), bg = 1:11, inches = FALSE, add = TRUE) dev.off() print(img) # Vectorized example with custom coordinates earth <- image_read("https://jeroen.github.io/images/earth.gif") img <- image_draw(earth, xlim = c(0,1), ylim = c(0,1)) rect(.1, .1, .9, .9, border = "red", lty = "dashed", lwd = 5) text(.5, .9, "Our planet", cex = 3, col = "white") dev.off() print(img)
# Regular image frink <- image_read("https://jeroen.github.io/images/frink.png") # Produce image using graphics device fig <- image_graph(res = 96) ggplot2::qplot(mpg, wt, data = mtcars, colour = cyl) dev.off() # Combine out <- image_composite(fig, frink, offset = "+70+30") print(out) # Or paint over an existing image img <- image_draw(frink) rect(20, 20, 200, 100, border = "red", lty = "dashed", lwd = 5) abline(h = 300, col = 'blue', lwd = '10', lty = "dotted") text(10, 250, "Hoiven-Glaven", family = "monospace", cex = 4, srt = 90) palette(rainbow(11, end = 0.9)) symbols(rep(200, 11), seq(0, 400, 40), circles = runif(11, 5, 35), bg = 1:11, inches = FALSE, add = TRUE) dev.off() print(img) # Vectorized example with custom coordinates earth <- image_read("https://jeroen.github.io/images/earth.gif") img <- image_draw(earth, xlim = c(0,1), ylim = c(0,1)) rect(.1, .1, .9, .9, border = "red", lty = "dashed", lwd = 5) text(.5, .9, "Our planet", cex = 3, col = "white") dev.off() print(img)
Best results are obtained by finding edges with image_canny()
and
then performing Hough-line detection on the edge image.
image_edge(image, radius = 1) image_canny(image, geometry = "0x1+10%+30%") image_hough_draw( image, geometry = NULL, color = "red", bg = "transparent", size = 3, overlay = FALSE ) image_hough_txt(image, geometry = NULL, format = c("mvg", "svg"))
image_edge(image, radius = 1) image_canny(image, geometry = "0x1+10%+30%") image_hough_draw( image, geometry = NULL, color = "red", bg = "transparent", size = 3, overlay = FALSE ) image_hough_txt(image, geometry = NULL, format = c("mvg", "svg"))
image |
magick image object returned by |
radius |
edge size in pixels |
geometry |
geometry string, see details. |
color |
a valid color string such as
|
bg |
background color |
size |
size in points to draw the line |
overlay |
composite the drawing atop the input image. Only for |
format |
output format of the text, either |
For Hough-line detection, the geometry format is {W}x{H}+{threshold}
defining the size and threshold of the filter used to find 'peaks' in
the intermediate search image. For canny edge detection the format is
{radius}x{sigma}+{lower%}+{upper%}
. More details and examples are
available at the imagemagick website.
Other image:
_index_
,
analysis
,
animation
,
attributes()
,
color
,
composite
,
defines
,
device
,
editing
,
effects()
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
if(magick_config()$version > "6.8.9"){ shape <- demo_image("shape_rectangle.gif") rectangle <- image_canny(shape) rectangle |> image_hough_draw('5x5+20') rectangle |> image_hough_txt(format = 'svg') |> cat() }
if(magick_config()$version > "6.8.9"){ shape <- demo_image("shape_rectangle.gif") rectangle <- image_canny(shape) rectangle |> image_hough_draw('5x5+20') rectangle |> image_hough_txt(format = 'svg') |> cat() }
Read, write and join or combine images. All image functions are vectorized, meaning
they operate either on a single frame or a series of frames (e.g. a collage, video,
or animation). Besides paths and URLs, image_read()
supports commonly used bitmap
and raster object types.
image_read( path, density = NULL, depth = NULL, strip = FALSE, coalesce = TRUE, defines = NULL ) image_read_svg(path, width = NULL, height = NULL) image_read_pdf(path, pages = NULL, density = 300, password = "") image_read_video(path, fps = 1, format = "png") image_write( image, path = NULL, format = NULL, quality = NULL, depth = NULL, density = NULL, comment = NULL, flatten = FALSE, defines = NULL, compression = NULL ) image_convert( image, format = NULL, type = NULL, colorspace = NULL, depth = NULL, antialias = NULL, matte = NULL, interlace = NULL, profile = NULL ) image_data(image, channels = NULL, frame = 1) image_raster(image, frame = 1, tidy = TRUE) image_display(image, animate = TRUE) image_browse(image, browser = getOption("browser")) image_strip(image) image_blank(width, height, color = "none", pseudo_image = "", defines = NULL) image_destroy(image) image_join(...) image_attributes(image) image_get_artifact(image, artifact = "") demo_image(path)
image_read( path, density = NULL, depth = NULL, strip = FALSE, coalesce = TRUE, defines = NULL ) image_read_svg(path, width = NULL, height = NULL) image_read_pdf(path, pages = NULL, density = 300, password = "") image_read_video(path, fps = 1, format = "png") image_write( image, path = NULL, format = NULL, quality = NULL, depth = NULL, density = NULL, comment = NULL, flatten = FALSE, defines = NULL, compression = NULL ) image_convert( image, format = NULL, type = NULL, colorspace = NULL, depth = NULL, antialias = NULL, matte = NULL, interlace = NULL, profile = NULL ) image_data(image, channels = NULL, frame = 1) image_raster(image, frame = 1, tidy = TRUE) image_display(image, animate = TRUE) image_browse(image, browser = getOption("browser")) image_strip(image) image_blank(width, height, color = "none", pseudo_image = "", defines = NULL) image_destroy(image) image_join(...) image_attributes(image) image_get_artifact(image, artifact = "") demo_image(path)
path |
a file, url, or raster object or bitmap array |
density |
resolution to render pdf or svg |
depth |
color depth (either 8 or 16) |
strip |
drop image comments and metadata |
coalesce |
automatically |
defines |
a named character vector with extra options to control reading.
These are the |
width |
in pixels |
height |
in pixels |
pages |
integer vector with page numbers. Defaults to all pages. |
password |
user password to open protected pdf files |
fps |
how many images to capture per second of video. Set to
|
format |
output format such as |
image |
magick image object returned by |
quality |
number between 0 and 100 for jpeg quality. Defaults to 75. |
comment |
text string added to the image metadata for supported formats |
flatten |
should image be flattened before writing? This also replaces transparency with background color. |
compression |
a string with compression type from compress_types |
type |
string with imagetype
value from image_types for example |
colorspace |
string with a |
antialias |
enable anti-aliasing for text and strokes |
matte |
set to |
interlace |
string with interlace |
profile |
path to file with ICC color profile |
channels |
string with image channel(s) for example |
frame |
integer setting which frame to extract from the image |
tidy |
converts raster data to long form for use with geom_raster.
If |
animate |
support animations in the X11 display |
browser |
argument passed to browseURL |
color |
a valid color string such as
|
pseudo_image |
string with pseudo image
specification for example |
... |
several images or lists of images to be combined |
artifact |
string with name of the artifact to extract, see the image_deskew for an example. |
All standard base vector methods such as [, [[, c()
, as.list()
,
as.raster()
, rev()
, length()
, and print()
can be used to work with magick
image objects. Use the standard img[i]
syntax to extract a subset of the frames
from an image. The img[[i]]
method is an alias for image_data()
which extracts
a single frame as a raw bitmap matrix with pixel values.
For reading svg or pdf it is recommended to use image_read_svg()
and image_read_pdf()
if the rsvg and pdftools R packages are available.
These functions provide more rendering options (including rendering of literal svg) and
better quality than built-in svg/pdf rendering delegates from imagemagick itself.
X11 is required for image_display()
which is only works on some platforms. A more
portable method is image_browse()
which opens the image in a browser. RStudio has
an embedded viewer that does this automatically which is quite nice.
Image objects are automatically released by the garbage collector when they are no longer
reachable. Because the GC only runs once in a while, you can also call image_destroy()
explicitly to release the memory immediately. This is usually only needed if you create
a lot of images in a short period of time, and you might run out of memory.
Other image:
_index_
,
analysis
,
animation
,
attributes()
,
color
,
composite
,
defines
,
device
,
edges
,
effects()
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
# Download image from the web frink <- image_read("https://jeroen.github.io/images/frink.png") worldcup_frink <- image_fill(frink, "orange", "+100+200", 20) image_write(worldcup_frink, "output.png") # extract raw bitmap array bitmap <- frink[[1]] # replace pixels with #FF69B4 ('hot pink') and convert back to image bitmap[,50:100, 50:100] <- as.raw(c(0xff, 0x69, 0xb4, 0xff)) image_read(bitmap) # Plot to graphics device via legacy raster format raster <- as.raster(frink) par(ask=FALSE) plot(raster) # Read bitmap arrays from other image packages download.file("https://jeroen.github.io/images/example.webp", "example.webp", mode = 'wb') if(require(webp)) image_read(webp::read_webp("example.webp")) unlink(c("example.webp", "output.png")) if(require(rsvg)){ tiger <- image_read_svg("http://jeroen.github.io/images/tiger.svg") svgtxt <- '<?xml version="1.0" encoding="UTF-8"?> <svg width="400" height="400" viewBox="0 0 400 400" fill="none"> <circle fill="steelblue" cx="200" cy="200" r="100" /> <circle fill="yellow" cx="200" cy="200" r="90" /> </svg>' circles <- image_read_svg(svgtxt) } if(require(pdftools)) image_read_pdf(file.path(R.home('doc'), 'NEWS.pdf'), pages = 1, density = 100) # create a solid canvas image_blank(600, 400, "green") image_blank(600, 400, pseudo_image = "radial-gradient:purple-yellow") image_blank(200, 200, pseudo_image = "gradient:#3498db-#db3a34", defines = c('gradient:direction' = 'east'))
# Download image from the web frink <- image_read("https://jeroen.github.io/images/frink.png") worldcup_frink <- image_fill(frink, "orange", "+100+200", 20) image_write(worldcup_frink, "output.png") # extract raw bitmap array bitmap <- frink[[1]] # replace pixels with #FF69B4 ('hot pink') and convert back to image bitmap[,50:100, 50:100] <- as.raw(c(0xff, 0x69, 0xb4, 0xff)) image_read(bitmap) # Plot to graphics device via legacy raster format raster <- as.raster(frink) par(ask=FALSE) plot(raster) # Read bitmap arrays from other image packages download.file("https://jeroen.github.io/images/example.webp", "example.webp", mode = 'wb') if(require(webp)) image_read(webp::read_webp("example.webp")) unlink(c("example.webp", "output.png")) if(require(rsvg)){ tiger <- image_read_svg("http://jeroen.github.io/images/tiger.svg") svgtxt <- '<?xml version="1.0" encoding="UTF-8"?> <svg width="400" height="400" viewBox="0 0 400 400" fill="none"> <circle fill="steelblue" cx="200" cy="200" r="100" /> <circle fill="yellow" cx="200" cy="200" r="90" /> </svg>' circles <- image_read_svg(svgtxt) } if(require(pdftools)) image_read_pdf(file.path(R.home('doc'), 'NEWS.pdf'), pages = 1, density = 100) # create a solid canvas image_blank(600, 400, "green") image_blank(600, 400, pseudo_image = "radial-gradient:purple-yellow") image_blank(200, 200, pseudo_image = "gradient:#3498db-#db3a34", defines = c('gradient:direction' = 'east'))
High level effects applied to an entire image. These are mostly just for fun.
image_despeckle(image, times = 1L) image_reducenoise(image, radius = 1L) image_noise(image, noisetype = "gaussian") image_blur(image, radius = 1, sigma = 0.5) image_motion_blur(image, radius = 1, sigma = 0.5, angle = 0) image_charcoal(image, radius = 1, sigma = 0.5) image_oilpaint(image, radius = 1) image_emboss(image, radius = 1, sigma = 0.5) image_implode(image, factor = 0.5) image_negate(image)
image_despeckle(image, times = 1L) image_reducenoise(image, radius = 1L) image_noise(image, noisetype = "gaussian") image_blur(image, radius = 1, sigma = 0.5) image_motion_blur(image, radius = 1, sigma = 0.5, angle = 0) image_charcoal(image, radius = 1, sigma = 0.5) image_oilpaint(image, radius = 1) image_emboss(image, radius = 1, sigma = 0.5) image_implode(image, factor = 0.5) image_negate(image)
image |
magick image object returned by |
times |
number of times to repeat the despeckle operation |
radius |
radius, in pixels, for various transformations |
noisetype |
string with a noisetype value from noise_types. |
sigma |
the standard deviation of the Laplacian, in pixels. |
angle |
angle, in degrees, for various transformations |
factor |
image implode factor (special effect) |
Other image:
_index_
,
analysis
,
animation
,
attributes()
,
color
,
composite
,
defines
,
device
,
edges
,
editing
,
fx
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
logo <- image_read("logo:") image_despeckle(logo) image_reducenoise(logo) image_noise(logo) image_blur(logo, 10, 10) image_motion_blur(logo, 10, 10, 45) image_charcoal(logo) image_oilpaint(logo, radius = 3) image_emboss(logo) image_implode(logo) image_negate(logo)
logo <- image_read("logo:") image_despeckle(logo) image_reducenoise(logo) image_noise(logo) image_blur(logo, 10, 10) image_motion_blur(logo, 10, 10, 45) image_charcoal(logo) image_oilpaint(logo, radius = 3) image_emboss(logo) image_implode(logo) image_negate(logo)
Apply a custom an fx expression to the image.
image_fx(image, expression = "p", channel = NULL) image_fx_sequence(image, expression = "p")
image_fx(image, expression = "p", channel = NULL) image_fx_sequence(image, expression = "p")
image |
magick image object returned by |
expression |
string with an fx expression |
channel |
a value of |
There are two different interfaces. The image_fx function simply applies the same fx to each frame in the input image. The image_fx_sequence function on the other hand treats the entire input vector as a sequence, allowing you to apply an expression with multiple input images. See examples.
Other image:
_index_
,
analysis
,
animation
,
attributes()
,
color
,
composite
,
defines
,
device
,
edges
,
editing
,
effects()
,
geometry
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
# Show image_fx() expression img <- image_convert(logo, colorspace = "Gray") gradient_x <- image_convolve(img, kernel = "Prewitt") gradient_y <- image_convolve(img, kernel = "Prewitt:90") gradient <- c(image_fx(gradient_x, expression = "p^2"), image_fx(gradient_y, expression = "p^2")) gradient <- image_flatten(gradient, operator = "Plus") #gradient <- image_fx(gradient, expression = "sqrt(p)") gradient image_fx(img, expression = "pow(p, 0.5)") image_fx(img, expression = "rand()") # Use multiple source images input <- c(logo, image_flop(logo)) image_fx_sequence(input, "(u+v)/2")
# Show image_fx() expression img <- image_convert(logo, colorspace = "Gray") gradient_x <- image_convolve(img, kernel = "Prewitt") gradient_y <- image_convolve(img, kernel = "Prewitt:90") gradient <- c(image_fx(gradient_x, expression = "p^2"), image_fx(gradient_y, expression = "p^2")) gradient <- image_flatten(gradient, operator = "Plus") #gradient <- image_fx(gradient, expression = "sqrt(p)") gradient image_fx(img, expression = "pow(p, 0.5)") image_fx(img, expression = "rand()") # Use multiple source images input <- c(logo, image_flop(logo)) image_fx_sequence(input, "(u+v)/2")
ImageMagick uses a handy geometry syntax to specify coordinates and shapes for use in image transformations. You can either specify these manually as strings or use the helper functions below.
geometry_point(x, y) geometry_area(width = NULL, height = NULL, x_off = 0, y_off = 0) geometry_size_pixels(width = NULL, height = NULL, preserve_aspect = TRUE) geometry_size_percent(width = 100, height = NULL)
geometry_point(x, y) geometry_area(width = NULL, height = NULL, x_off = 0, y_off = 0) geometry_size_pixels(width = NULL, height = NULL, preserve_aspect = TRUE) geometry_size_percent(width = 100, height = NULL)
x |
left offset in pixels |
y |
top offset in pixels |
width |
in pixels |
height |
in pixels |
x_off |
offset in pixels on x axis |
y_off |
offset in pixels on y axis |
preserve_aspect |
if FALSE, resize to width and height exactly, loosing original
aspect ratio. Only one of |
See ImageMagick Manual
for details about the syntax specification.
Examples of geometry
strings:
"500x300"
– Resize image keeping aspect ratio, such that width does not exceed 500 and the height does not exceed 300.
"500x300!"
– Resize image to 500 by 300, ignoring aspect ratio
"500x"
– Resize width to 500 keep aspect ratio
"x300"
– Resize height to 300 keep aspect ratio
"50%x20%"
– Resize width to 50 percent and height to 20 percent of original
"500x300+10+20"
– Crop image to 500 by 300 at position 10,20
Other image:
_index_
,
analysis
,
animation
,
attributes()
,
color
,
composite
,
defines
,
device
,
edges
,
editing
,
effects()
,
fx
,
morphology
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
# Specify a point logo <- image_read("logo:") image_annotate(logo, "Some text", location = geometry_point(100, 200), size = 24) # Specify image area image_crop(logo, geometry_area(300, 300), repage = FALSE) image_crop(logo, geometry_area(300, 300, 100, 100), repage = FALSE) # Specify image size image_resize(logo, geometry_size_pixels(300)) image_resize(logo, geometry_size_pixels(height = 300)) image_resize(logo, geometry_size_pixels(300, 300, preserve_aspect = FALSE)) # resize relative to current size image_resize(logo, geometry_size_percent(50)) image_resize(logo, geometry_size_percent(50, 20))
# Specify a point logo <- image_read("logo:") image_annotate(logo, "Some text", location = geometry_point(100, 200), size = 24) # Specify image area image_crop(logo, geometry_area(300, 300), repage = FALSE) image_crop(logo, geometry_area(300, 300, 100, 100), repage = FALSE) # Specify image size image_resize(logo, geometry_size_pixels(300)) image_resize(logo, geometry_size_pixels(height = 300)) image_resize(logo, geometry_size_pixels(300, 300, preserve_aspect = FALSE)) # resize relative to current size image_resize(logo, geometry_size_percent(50)) image_resize(logo, geometry_size_percent(50, 20))
Create a ggplot with axes set to pixel coordinates and plot the raster image on it using ggplot2::annotation_raster. See examples for how to plot an image onto an existing ggplot.
image_ggplot(image, interpolate = FALSE)
image_ggplot(image, interpolate = FALSE)
image |
magick image object returned by |
interpolate |
passed to ggplot2::annotation_raster |
# Plot with base R plot(logo) # Plot image with ggplot2 library(ggplot2) myplot <- image_ggplot(logo) myplot + ggtitle("Test plot") # Show that coordinates are reversed: myplot + theme_classic() # Or add to plot as annotation image <- image_fill(logo, 'none') raster <- as.raster(image) myplot <- qplot(mpg, wt, data = mtcars) myplot + annotation_raster(raster, 25, 35, 3, 5) # Or overplot image using grid library(grid) qplot(speed, dist, data = cars, geom = c("point", "smooth")) grid.raster(image)
# Plot with base R plot(logo) # Plot image with ggplot2 library(ggplot2) myplot <- image_ggplot(logo) myplot + ggtitle("Test plot") # Show that coordinates are reversed: myplot + theme_classic() # Or add to plot as annotation image <- image_fill(logo, 'none') raster <- as.raster(image) myplot <- qplot(mpg, wt, data = mtcars) myplot + annotation_raster(raster, 25, 35, 3, 5) # Or overplot image using grid library(grid) qplot(speed, dist, data = cars, geom = c("point", "smooth")) grid.raster(image)
Apply a morphology method. This is a very flexible function which can be used to apply any morphology method with custom parameters. See imagemagick website for examples.
image_morphology( image, method = "convolve", kernel = "Gaussian", iterations = 1, opts = list() ) image_convolve( image, kernel = "Gaussian", iterations = 1, scaling = NULL, bias = NULL )
image_morphology( image, method = "convolve", kernel = "Gaussian", iterations = 1, opts = list() ) image_convolve( image, kernel = "Gaussian", iterations = 1, scaling = NULL, bias = NULL )
image |
magick image object returned by |
method |
a string with a valid method from |
kernel |
either a square matrix or a string. The string can either be a
parameterized kerneltype such as: |
iterations |
number of iterations |
opts |
a named list or character vector with custom attributes |
scaling |
string with kernel scaling. The special flag |
bias |
output bias string, for example |
Other image:
_index_
,
analysis
,
animation
,
attributes()
,
color
,
composite
,
defines
,
device
,
edges
,
editing
,
effects()
,
fx
,
geometry
,
ocr
,
options()
,
painting
,
segmentation
,
transform()
,
video
#example from IM website: if(magick_config()$version > "6.8.8"){ pixel <- image_blank(1, 1, 'white') |> image_border('black', '5x5') # See the effect of Dilate method pixel |> image_scale('800%') pixel |> image_morphology('Dilate', "Diamond") |> image_scale('800%') # These produce the same output: pixel |> image_morphology('Dilate', "Diamond", iter = 3) |> image_scale('800%') pixel |> image_morphology('Dilate', "Diamond:3") |> image_scale('800%') # Plus example pixel |> image_morphology('Dilate', "Plus", iterations = 2) |> image_scale('800%') # Rose examples rose |> image_morphology('ErodeI', 'Octagon', iter = 3) rose |> image_morphology('DilateI', 'Octagon', iter = 3) rose |> image_morphology('OpenI', 'Octagon', iter = 3) rose |> image_morphology('CloseI', 'Octagon', iter = 3) # Edge detection man <- demo_image('man.gif') man |> image_morphology('EdgeIn', 'Octagon') man |> image_morphology('EdgeOut', 'Octagon') man |> image_morphology('Edge', 'Octagon') # Octagonal Convex Hull man |> image_morphology('Close', 'Diamond') |> image_morphology('Thicken', 'ConvexHull', iterations = 1) # Thinning down to a Skeleton man |> image_morphology('Thinning', 'Skeleton', iterations = 1) # Specify custom kernel matrix usingn a string: img <- demo_image("test_mag.gif") i <- image_convolve(img, kernel = '4x5: 0 -1 0 0 -1 +1 -1 0 -1 +1 -1 0 -1 +1 +1 -1 0 -1 -1 0 ', bias = "50%") }
#example from IM website: if(magick_config()$version > "6.8.8"){ pixel <- image_blank(1, 1, 'white') |> image_border('black', '5x5') # See the effect of Dilate method pixel |> image_scale('800%') pixel |> image_morphology('Dilate', "Diamond") |> image_scale('800%') # These produce the same output: pixel |> image_morphology('Dilate', "Diamond", iter = 3) |> image_scale('800%') pixel |> image_morphology('Dilate', "Diamond:3") |> image_scale('800%') # Plus example pixel |> image_morphology('Dilate', "Plus", iterations = 2) |> image_scale('800%') # Rose examples rose |> image_morphology('ErodeI', 'Octagon', iter = 3) rose |> image_morphology('DilateI', 'Octagon', iter = 3) rose |> image_morphology('OpenI', 'Octagon', iter = 3) rose |> image_morphology('CloseI', 'Octagon', iter = 3) # Edge detection man <- demo_image('man.gif') man |> image_morphology('EdgeIn', 'Octagon') man |> image_morphology('EdgeOut', 'Octagon') man |> image_morphology('Edge', 'Octagon') # Octagonal Convex Hull man |> image_morphology('Close', 'Diamond') |> image_morphology('Thicken', 'ConvexHull', iterations = 1) # Thinning down to a Skeleton man |> image_morphology('Thinning', 'Skeleton', iterations = 1) # Specify custom kernel matrix usingn a string: img <- demo_image("test_mag.gif") i <- image_convolve(img, kernel = '4x5: 0 -1 0 0 -1 +1 -1 0 -1 +1 -1 0 -1 +1 +1 -1 0 -1 -1 0 ', bias = "50%") }
Extract text from an image using the tesseract package.
image_ocr(image, language = "eng", HOCR = FALSE, ...) image_ocr_data(image, language = "eng", ...)
image_ocr(image, language = "eng", HOCR = FALSE, ...) image_ocr_data(image, language = "eng", ...)
image |
magick image object returned by |
language |
passed to tesseract. To install additional languages see instructions in tesseract_download(). |
HOCR |
if |
... |
additional parameters passed to tesseract |
To use this function you need to tesseract first:
install.packages("tesseract")
Best results are obtained if you set the correct language in tesseract. To install additional languages see instructions in tesseract_download().
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if(require("tesseract")){ img <- image_read("http://jeroen.github.io/images/testocr.png") image_ocr(img) image_ocr_data(img) }
if(require("tesseract")){ img <- image_read("http://jeroen.github.io/images/testocr.png") image_ocr(img) image_ocr_data(img) }
List option types and values supported in your version of ImageMagick. For descriptions see ImageMagick Enumerations.
magick_options() magick_fonts() option_types() filter_types() metric_types() dispose_types() compose_types() colorspace_types() channel_types() image_types() kernel_types() noise_types() gravity_types() orientation_types() morphology_types() style_types() decoration_types() compress_types() distort_types() dump_option_info(option = "font")
magick_options() magick_fonts() option_types() filter_types() metric_types() dispose_types() compose_types() colorspace_types() channel_types() image_types() kernel_types() noise_types() gravity_types() orientation_types() morphology_types() style_types() decoration_types() compress_types() distort_types() dump_option_info(option = "font")
option |
one of the option_types |
The dump_option_info function is equivalent to calling convert -list [option]
on
the command line. It does not return anything, it only makes ImageMagick print
stuff to the console, use only for debugging.
ImageMagick Manual: Enumerations
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The image_fill()
function performs flood-fill by painting starting point and all
neighboring pixels of approximately the same color. Annotate prints some text on
the image.
image_fill(image, color, point = "+1+1", fuzz = 0, refcolor = NULL) image_annotate( image, text, gravity = "northwest", location = "+0+0", degrees = 0, size = 10, font = "", style = "normal", weight = 400, kerning = 0, decoration = NULL, color = NULL, strokecolor = NULL, strokewidth = NULL, boxcolor = NULL )
image_fill(image, color, point = "+1+1", fuzz = 0, refcolor = NULL) image_annotate( image, text, gravity = "northwest", location = "+0+0", degrees = 0, size = 10, font = "", style = "normal", weight = 400, kerning = 0, decoration = NULL, color = NULL, strokecolor = NULL, strokewidth = NULL, boxcolor = NULL )
image |
magick image object returned by |
color |
a valid color string such as
|
point |
a geometry_point string indicating the starting point of the flood-fill |
fuzz |
relative color distance (value between 0 and 100) to be considered similar in the filling algorithm |
refcolor |
if set, |
text |
character vector of length equal to 'image' or length 1 |
gravity |
string with gravity value from gravity_types. |
location |
geometry string with location relative to |
degrees |
rotates text around center point |
size |
font-size in pixels |
font |
string with font family such as |
style |
value of style_types for example |
weight |
thickness of the font, 400 is normal and 700 is bold, see |
kerning |
increases or decreases whitespace between letters |
decoration |
value of decoration_types for example |
strokecolor |
a color string adds a stroke (border around the text) |
strokewidth |
set the strokewidth of the border around the text |
boxcolor |
a color string for background color that annotation text is rendered on. |
Note that more sophisticated drawing mechanisms are available via the graphics device using image_draw.
Setting a font, weight, style only works if your imagemagick is compiled with fontconfig support.
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logo <- image_read("logo:") logo <- image_background(logo, 'white') image_fill(logo, "pink", point = "+450+400") image_fill(logo, "pink", point = "+450+400", fuzz = 25) # Add some text to an image image_annotate(logo, "This is a test") image_annotate(logo, "CONFIDENTIAL", size = 50, color = "red", boxcolor = "pink", degrees = 30, location = "+100+100") # Setting fonts requires fontconfig support (and that you have the font) image_annotate(logo, "The quick brown fox", font = "monospace", size = 50)
logo <- image_read("logo:") logo <- image_background(logo, 'white') image_fill(logo, "pink", point = "+450+400") image_fill(logo, "pink", point = "+450+400", fuzz = 25) # Add some text to an image image_annotate(logo, "This is a test") image_annotate(logo, "CONFIDENTIAL", size = 50, color = "red", boxcolor = "pink", degrees = 30, location = "+100+100") # Setting fonts requires fontconfig support (and that you have the font) image_annotate(logo, "The quick brown fox", font = "monospace", size = 50)
Basic image segmentation like connected components labelling, blob extraction and fuzzy c-means
image_connect(image, connectivity = 4) image_split(image, keep_color = TRUE) image_fuzzycmeans(image, min_pixels = 1, smoothing = 1.5)
image_connect(image, connectivity = 4) image_split(image, keep_color = TRUE) image_fuzzycmeans(image, min_pixels = 1, smoothing = 1.5)
image |
magick image object returned by |
connectivity |
number neighbor colors which are considered part of a unique object |
keep_color |
if TRUE the output images retain the color of the input pixel. If FALSE all matching pixels are set black to retain only the image mask. |
min_pixels |
the minimum number of pixels contained in a hexahedra before it can be considered valid (expressed as a percentage) |
smoothing |
the smoothing threshold which eliminates noise in the second derivative of the histogram (higher values gives smoother second derivative) |
image_connect Connect adjacent pixels with the same pixel intensities to do blob extraction
image_split Splits the image according to pixel intensities
image_fuzzycmeans Fuzzy c-means segmentation of the histogram of color components
image_connect performs blob extraction by scanning the image, pixel-by-pixel from top-left to bottom-right where regions of adjacent pixels which share the same set of intensity values get combined.
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# Split an image by color img <- image_quantize(logo, 4) layers <- image_split(img) layers # This returns the original image image_flatten(layers) # From the IM website objects <- image_convert(demo_image("objects.gif"), colorspace = "Gray") objects # Split image in blobs of connected pixel levels if(magick_config()$version > "6.9.0"){ objects |> image_connect(connectivity = 4) |> image_split() # Fuzzy c-means image_fuzzycmeans(logo) logo |> image_convert(colorspace = "HCL") |> image_fuzzycmeans(smoothing = 5) }
# Split an image by color img <- image_quantize(logo, 4) layers <- image_split(img) layers # This returns the original image image_flatten(layers) # From the IM website objects <- image_convert(demo_image("objects.gif"), colorspace = "Gray") objects # Split image in blobs of connected pixel levels if(magick_config()$version > "6.9.0"){ objects |> image_connect(connectivity = 4) |> image_split() # Fuzzy c-means image_fuzzycmeans(logo) logo |> image_convert(colorspace = "HCL") |> image_fuzzycmeans(smoothing = 5) }
Thresholding an image can be used for simple and straightforward image segmentation.
The function image_threshold()
allows to do black and white thresholding whereas
image_lat()
performs local adaptive thresholding.
image_threshold( image, type = c("black", "white"), threshold = "50%", channel = NULL ) image_level( image, black_point = 0, white_point = 100, mid_point = 1, channel = NULL ) image_lat(image, geometry = "10x10+5%")
image_threshold( image, type = c("black", "white"), threshold = "50%", channel = NULL ) image_level( image, black_point = 0, white_point = 100, mid_point = 1, channel = NULL ) image_lat(image, geometry = "10x10+5%")
image |
magick image object returned by |
type |
type of thresholding, either one of lat, black or white (see details below) |
threshold |
pixel intensity threshold percentage for black or white thresholding |
channel |
a value of |
black_point |
value between 0 and 100, the darkest color in the image |
white_point |
value between 0 and 100, the lightest color in the image |
mid_point |
value between 0 and 10 used for gamma correction |
geometry |
pixel window plus offset for LAT algorithm |
image_threshold(type = "black")
: Forces all pixels below the threshold into black while leaving all pixels
at or above the threshold unchanged
image_threshold(type = "white")
: Forces all pixels above the threshold into white while leaving all pixels
at or below the threshold unchanged
image_lat()
: Local Adaptive Thresholding. Looks in a box (width x height) around the
pixel neighborhood if the pixel value is bigger than the average minus an offset.
test <- image_convert(logo, colorspace = "Gray") image_threshold(test, type = "black", threshold = "50%") image_threshold(test, type = "white", threshold = "50%") # Turn image into BW test |> image_threshold(type = "white", threshold = "50%") |> image_threshold(type = "black", threshold = "50%") # adaptive thresholding image_lat(test, geometry = '10x10+5%')
test <- image_convert(logo, colorspace = "Gray") image_threshold(test, type = "black", threshold = "50%") image_threshold(test, type = "white", threshold = "50%") # Turn image into BW test |> image_threshold(type = "white", threshold = "50%") |> image_threshold(type = "black", threshold = "50%") # adaptive thresholding image_lat(test, geometry = '10x10+5%')
Basic transformations like rotate, resize, crop and flip. The geometry syntax is used to specify sizes and areas.
image_trim(image, fuzz = 0) image_chop(image, geometry) image_rotate(image, degrees) image_resize(image, geometry = NULL, filter = NULL) image_scale(image, geometry = NULL) image_sample(image, geometry = NULL) image_crop(image, geometry = NULL, gravity = NULL, repage = TRUE) image_extent(image, geometry, gravity = "center", color = "none") image_flip(image) image_flop(image) image_deskew(image, threshold = 40) image_deskew_angle(image, threshold = 40) image_page(image, pagesize = NULL, density = NULL) image_repage(image) image_orient(image, orientation = NULL) image_shear(image, geometry = "10x10", color = "none") image_distort(image, distortion = "perspective", coordinates, bestfit = FALSE)
image_trim(image, fuzz = 0) image_chop(image, geometry) image_rotate(image, degrees) image_resize(image, geometry = NULL, filter = NULL) image_scale(image, geometry = NULL) image_sample(image, geometry = NULL) image_crop(image, geometry = NULL, gravity = NULL, repage = TRUE) image_extent(image, geometry, gravity = "center", color = "none") image_flip(image) image_flop(image) image_deskew(image, threshold = 40) image_deskew_angle(image, threshold = 40) image_page(image, pagesize = NULL, density = NULL) image_repage(image) image_orient(image, orientation = NULL) image_shear(image, geometry = "10x10", color = "none") image_distort(image, distortion = "perspective", coordinates, bestfit = FALSE)
image |
magick image object returned by |
fuzz |
relative color distance (value between 0 and 100) to be considered similar in the filling algorithm |
geometry |
a geometry string specifying area (for cropping) or size (for resizing). |
degrees |
value between 0 and 360 for how many degrees to rotate |
filter |
string with filter type from: filter_types |
gravity |
string with gravity value from gravity_types. |
repage |
resize the canvas to the cropped area |
color |
a valid color string such as
|
threshold |
straightens an image. A threshold of 40 works for most images. |
pagesize |
geometry string with preferred size and location of an image canvas |
density |
geometry string with vertical and horizontal resolution in pixels of the image. Specifies an image density when decoding a Postscript or PDF. |
orientation |
string to set image orientation one of the orientation_types.
If |
distortion |
string to set image orientation one of the distort_types. |
coordinates |
numeric vector (typically of length 12) with distortion coordinates |
bestfit |
if set to |
For details see Magick++ STL documentation. Short descriptions:
image_trim removes edges that are the background color from the image.
image_chop removes vertical or horizontal subregion of image.
image_crop cuts out a subregion of original image
image_rotate rotates and increases size of canvas to fit rotated image.
image_deskew auto rotate to correct skewed images
image_resize resizes using custom filterType
image_scale and image_sample resize using simple ratio and pixel sampling algorithm.
image_flip and image_flop invert image vertically and horizontally
The most powerful resize function is image_resize which allows for setting
a custom resize filter. Output of image_scale is similar to image_resize(img, filter = "point")
.
For resize operations it holds that if no geometry
is specified, all frames
are rescaled to match the top frame.
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logo <- image_read("logo:") logo <- image_scale(logo, "400") image_trim(logo) image_chop(logo, "100x20") image_rotate(logo, 45) # Small image rose <- image_convert(image_read("rose:"), "png") # Resize to 400 width or height: image_resize(rose, "400x") image_resize(rose, "x400") # Resize keeping ratio image_resize(rose, "400x400") # Resize, force size losing ratio image_resize(rose, "400x400!") # Different filters image_resize(rose, "400x", filter = "Triangle") image_resize(rose, "400x", filter = "Point") # simple pixel resize image_scale(rose, "400x") image_sample(rose, "400x") image_crop(logo, "400x400+200+200") image_extent(rose, '200x200', color = 'pink') image_flip(logo) image_flop(logo) skewed <- image_rotate(logo, 5) deskewed <- image_deskew(skewed) attr(deskewed, 'angle') if(magick_config()$version > "6.8.6") image_orient(logo) image_shear(logo, "10x10") building <- demo_image('building.jpg') image_distort(building, 'perspective', c(7,40,4,30,4,124,4,123,85,122,100,123,85,2,100,30))
logo <- image_read("logo:") logo <- image_scale(logo, "400") image_trim(logo) image_chop(logo, "100x20") image_rotate(logo, 45) # Small image rose <- image_convert(image_read("rose:"), "png") # Resize to 400 width or height: image_resize(rose, "400x") image_resize(rose, "x400") # Resize keeping ratio image_resize(rose, "400x400") # Resize, force size losing ratio image_resize(rose, "400x400!") # Different filters image_resize(rose, "400x", filter = "Triangle") image_resize(rose, "400x", filter = "Point") # simple pixel resize image_scale(rose, "400x") image_sample(rose, "400x") image_crop(logo, "400x400+200+200") image_extent(rose, '200x200', color = 'pink') image_flip(logo) image_flop(logo) skewed <- image_rotate(logo, 5) deskewed <- image_deskew(skewed) attr(deskewed, 'angle') if(magick_config()$version > "6.8.6") image_orient(logo) image_shear(logo, "10x10") building <- demo_image('building.jpg') image_distort(building, 'perspective', c(7,40,4,30,4,124,4,123,85,122,100,123,85,2,100,30))
High quality video / gif exporter based on external packages gifski and av.
image_write_video(image, path = NULL, framerate = 10, ...) image_write_gif(image, path = NULL, delay = 1/10, ...)
image_write_video(image, path = NULL, framerate = 10, ...) image_write_gif(image, path = NULL, delay = 1/10, ...)
image |
magick image object returned by |
path |
filename of the output gif or video. This is also the return value. |
framerate |
frames per second, passed to av_encode_video |
... |
additional parameters passed to av_encode_video and gifski. |
delay |
duration of each frame in seconds (inverse of framerate) |
This requires an image with multiple frames. The GIF exporter accomplishes the same thing as image_animate but much faster and with better quality.
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Example images included with ImageMagick:
logo
logo
An object of class magick-image
of length 1.
logo
: ImageMagick Logo, 640x480
wizard
: ImageMagick Wizard, 480x640
rose
: Picture of a rose, 70x46
granite
: Granite texture pattern, 128x128