ruby-vips

This gem is a Ruby binding for the libvips image processing 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+.

Requirements

• macOS, Linux, and Windows tested

• libvips 8.2 or later, see the libvips install instructions

• ruby-ffi 1.9 or later

• Ruby 2.0+, JRuby

Install

Install libvips, then:

$ gem install ruby-vips

or include it in Gemfile:

gem "ruby-vips"

On Windows, you'll need to set the RUBY_DLL_PATH environment variable to point to the libvips bin directory.

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://libvips.github.io/libvips/API/current/libvips-conversion.html#vips-embed
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.