Image Processing Library Based on 'CImg'

Fast image processing for images in up to 4 dimensions (two spatial dimensions, one time/depth dimension, one colour dimension). Provides most traditional image processing tools (filtering, morphology, transformations, etc.) as well as various functions for easily analysing image data using R. The package wraps CImg, < http://cimg.eu>, a simple, modern C++ library for image processing.


Imager is an image/video processing package for R, based on CImg, a C++ library by David Tschumperlé. CImg provides an easy-to-use and consistent API for image processing, which imager largely replicates. CImg supports images in up to four dimensions, which makes it suitable for applications like video processing/hyperspectral imaging/MRI.

Imager is now on CRAN, so

install.packages("imager")

should do the trick. You may also want to install ImageMagick and ffmpeg, see "External Dependencies" below.

The version of CRAN will often lag the one on github. If you'd like to install the latest version, you'll have to build the package from source.

Install the devtools package if you haven't already. Run:

devtools::install_github("dahtah/imager")

If that doesn't work then you're probably missing a build environment or a library, see below.

Install XQuartz if you haven't already (it's required for the interactive functions). You'll need Xcode (OS X's development environment) to compile source packages. The FFTW library is needed, and the easiest way to install it is via Homebrew. Install Homebrew, then run: brew install fftw

Building R packages on Windows is a bit of a pain so you're probably better off with the binary package (which may not be up-to-date). If you need the latest version of imager, you'll have to:

  • Install Rtools
  • Install additional libraries for Rtools. You want the package that's called "local tree". Put those libraries somewhere gcc can find them.

To build under Linux make sure you have the headers for libX11 and libfftw3. On my Ubuntu system this seems to be enough:

sudo apt-get install libfftw3-dev libX11-dev

OS X users need XQuartz. On its own imager only supports JPEG, PNG and BMP formats. If you need support for other file types install ImageMagick. To load videos you'll need ffmpeg, no file formats are supported natively.

Here's a small demo that actually demonstrates an interesting property of colour perception:

library(imager)
library(purrr)
parrots <- load.example("parrots")
plot(parrots)
#Define a function that converts to YUV, blurs a specific channel, and converts back
bchan <- function(im,ind,sigma=5) { 
    im <- RGBtoYUV(im)
    channel(im,ind) <- isoblur(channel(im,ind),sigma); 
    YUVtoRGB(im)
}
#Run the function on all three channels and collect the results as a list
blurred <- map_il(1:3,~ bchan(parrots,.))
names(blurred) <- c("Luminance blur (Y)","Chrominance blur (U)","Chrominance blur (V)")
plot(blurred)

We're much more sensitive to luminance edges than we are to colour edges.

Documentation is available here. To get a list of all package functions, run: ls(pos = "package:imager")

All images are stored as standard R numeric vectors (i.e., double-precision), meaning that they take up a lot of memory. It's easy to underestimate how much storage you need for videos, because they take up so little space in a compressed format. Before you can work on it in R a video has to be fully decompressed and stored as double-precision floats. To get a sense of the size, consider a low-resolution (400x300), colour video lasting 120 sec. The video might take up a few MBs when compressed. To store it in memory, you'll need: (400x300) x (25x120) x 3 values, corresponding to (space)x(time)x(colour). In addition, each value costs 8 bytes of storage, for a grand total of 8GB of memory.

For out-of-memory processing of videos, see the experimental package imagerstreams.

Imager is fully functional but still young, so the API might change. Open an issue on Github or email me if you've found a bug or would like to suggest a feature.

Imager ships with four test pictures and a video. Two (parrots and boats) come from the Kodak set. Another is a sketch of birds by Leonardo, from Wikimedia. Also from Wikimedia: the Hubble Deep field. The test video comes from xiph.org's collection.

News

imager 0.31 Minor release

  • fixed inline C++ plugin, this time for OS X systems
  • added interpolation option to plot.cimg (to prevent systematic antialiasing when plotting small images)

imager 0.30 Major release.

  • new S3 class imlist improves support for image lists
  • enabled OpenMP. Many CImg primitives now run in parallel.
  • experimental support for CImg's DSL via imeval, patch_summary.
  • improved as.raster,plot. Now support palettes via colourscale argument.
  • new interactive functions for selecting image regions (grabRect,grabPoint,grabLine)
  • new patchstat function for fast extraction of patch statistics
  • new patchmatch function
  • cleaned up the API, improved the documentation
  • fixed bug in inline C++ plugin, should now work on Windows.
  • improved configure script. FFTW3 is now optional (should be less confusing to OSX users)

imager 0.20. Major release

  • added a tutorial (vignette), which includes a worked-out example of multi-scale blob detection
  • new functions:
    • iminfo gives you information on an image file (uses ImageMagick)
    • load.example loads test images
    • crop.borders (self-explanatory)
  • long computations can now be interrupted thanks to update in CImg
  • the array subset operator is now more intelligent: you do not have to specify flat dimensions, i.e. imfill(10,10)[3,1] does what you'd expect (i.e., the same as imfill(10,10)[3,1,1,1])
  • improvements and bugs fixed in print.cimg, as.cimg, imresize, frame, plot.cimg, subim, as.raster, renorm
  • improved documentation and examples

imager 0.16. Bugfix + minor features

  • as.data.frame.cimg now has optional "wide" formats
  • load.image now uses readbitmap by default (should work better on Windows)
  • Made the test for ImageMagick more stringent, which fixes a bug in load.image on certain machines
  • Added new reductions which.parmax, which.parmin

imager 0.15: Substantial update

  • User-visible changes:
    • the threshold function now supports auto-thresholding (based on k-means)
    • new accessor functions: imrow, imcol
    • new replacement functions: channel(im,1) <-, R(im) <- , etc.
    • new reduction function: enorm (Euclidean norm of a list of images)
    • improved as.cimg.function, pixel.grid
    • subim is now called imsub for greater consistency (imsub still available as alias)
    • improved documentation
  • Other:
    • Reorganised R code into separate files for clarity

0.14 Minor update

  • Build system now uses configure
  • Fixed paths in Makevars
  • Hopeful bugfix in load.image for Windows 7 users

0.13 Initial release on CRAN

Reference manual

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install.packages("imager")

0.31 by Simon Barthelme, 5 months ago


http://dahtah.github.io/imager, https://github.com/dahtah/imager


Report a bug at https://github.com/dahtah/imager/issues


Browse source code at https://github.com/cran/imager


Authors: Simon Barthelme [aut, cre], Antoine Cecchi [ctb]


Documentation:   PDF Manual  


LGPL license


Imports Rcpp, methods, stringr, png, jpeg, readbitmap, grDevices, purrr

Depends on plyr, magrittr

Suggests knitr, rmarkdown, ggplot2, dplyr, scales, testthat, OpenMPController

Enhances spatstat

Linking to Rcpp

System requirements: fftw3


Imported by ForestTools.


See at CRAN