editing: Image Editing

In magick: Advanced Graphics and Image-Processing in R

Image Editing

Description

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.

Usage

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)

Arguments

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 image_coalesce() gif images
defines	a named character vector with extra options to control reading. These are the ⁠-define key{=value}⁠ settings in the command line tool. Use an empty string for value-less defines, and NA to unset a define.
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 NULL to get all frames from the input video.
format	output format such as "png", "jpeg", "gif", "rgb" or "rgba".
image	magick image object returned by image_read() or image_graph()
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 grayscale to convert into black/white
colorspace	string with a colorspace from colorspace_types for example "gray", "rgb" or "cmyk"
antialias	enable anti-aliasing for text and strokes
matte	set to TRUE or FALSE to enable or disable transparency
interlace	string with interlace
profile	path to file with ICC color profile
channels	string with image channel(s) for example "rgb", "rgba", "cmyk","gray", or "ycbcr". Default is either "gray", "rgb" or "rgba" depending on the image
frame	integer setting which frame to extract from the image
tidy	converts raster data to long form for use with geom_raster. If FALSE output is the same as as.raster().
animate	support animations in the X11 display
browser	argument passed to browseURL
color	a valid color string such as "navyblue" or "#000080". Use "none" for transparency.
pseudo_image	string with pseudo image specification for example "radial-gradient:purple-yellow"
...	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.

Details

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.

See Also

Other image: _index_, analysis, animation, attributes(), color, composite, defines, device, edges, effects(), fx, geometry, morphology, ocr, options(), painting, segmentation, transform(), video

Examples

# 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'))

magick documentation built on Sept. 30, 2024, 9:39 a.m.