ruby-vips

This gem is a Ruby binding for the libvips image processing
library. It has been tested on
Linux, macOS and Windows, and with ruby 2, ruby 3 and jruby. It uses
ruby-ffi to call functions in the libvips
library.

libvips is a demand-driven, horizontally
threaded
image processing library. Compared to similar
libraries, libvips runs quickly and uses little
memory.
libvips is licensed under the LGPL
2.1+.

Install on linux and macOS

Install the libvips binary with your package manager (eg. apt install libvips42 or perhaps brew install vips, see the libvips install
instructions) then install
this gem with:

gem install ruby-vips

Or include gem "ruby-vips" in your gemfile.

Install on Windows

The gemspec will pull in the msys libvips for you, so all you need is:

gem install ruby-vips

Or include gem "ruby-vips" in your gemfile.

Tested with the ruby and msys from choco, but others may work.

Example

require "vips"

im = Vips::Image.new_from_file filename

# put im at position (100, 100) in a 3000 x 3000 pixel image, 
# make the other pixels in the image by mirroring im up / down / 
# left / right, see
# https://www.libvips.org/API/current/method.Image.embed.html
im = im.embed 100, 100, 3000, 3000, extend: :mirror

# multiply the green (middle) band by 2, leave the other two alone
im *= [1, 2, 1]

# make an image from an array constant, convolve with it
mask = Vips::Image.new_from_array [
    [-1, -1, -1],
    [-1, 16, -1],
    [-1, -1, -1]], 8
im = im.conv mask, precision: :integer

# finally, write the result back to a file on disk
im.write_to_file output_filename

Documentation

There are full API docs for ruby-vips on
rubydoc. This sometimes has issues
updating, so we have a copy on the gh-pages for this site as
well, which
should always work.

See the Vips section in the docs for a tutorial introduction with
examples.

The libvips reference manual
has a complete explanation of every method.

The example/
directory has some simple example programs.

Benchmarks

The benchmark at vips-benchmarks
loads a large image, crops, shrinks, sharpens and saves again, and repeats
10 times.

real time in seconds, fastest of five runs
benchmark       tiff    jpeg
ruby-vips.rb	0.85	0.78	
image-magick	2.03	2.44	
rmagick.rb	3.87	3.89	

peak memory use in kb
benchmark	peak RES
ruby-vips.rb	43864
rmagick.rb	788768

See also benchmarks at the official libvips
website.