This gem allows you to simply optimize images via jpegoptim or optipng.
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README.md

ImageOptimizer

This gem allows you to simply optimize images via jpegoptim or OptiPNG.

Tested against ruby 2.0.x, 2.1.x, 2.2.x, 2.3.x, and ruby-head

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Installation

This gem uses the following utilities for optimizing images:
  1. jpegoptim, which can be installed from freecode.com

  2. OptiPNG, which can be installed from sourceforge.net

  3. Gifsicle, which can be installed from www.lcdf.org/gifsicle/

  4. Pngquant, which can be installed from pngquant.org

Or install the utilities via homebrew:

$ brew install optipng jpegoptim gifsicle pngquant

Then add this line to your application's Gemfile:

gem 'image_optimizer'

And then execute:

$ bundle

Or install it yourself as:

$ gem install image_optimizer

Usage

Optimize PNG formats:

OptiPNG is a PNG optimizer that recompresses image files to a smaller size without losing any information and performs PNG integrity checks and corrections.

ImageOptimizer.new('path/to/file.png').optimize

Pngquant is a command-line utility and a library for lossy compression of PNG images. The conversion reduces file sizes significantly (often as much as 70%) and preserves full alpha transparency. Generated images are compatible with all modern web browsers, and have better fallback in IE6 than 24-bit PNGs.

ImageOptimizer::PNGQuantOptimizer.new('path/to/file.png').optimize

Optimize JPEG formats:

jpegoptim provides lossless optimization for JPEG files based on optimizing the Huffman tables. All jpegs will be progressively optimized for a better web experience

ImageOptimizer.new('path/to/file.jpg').optimize

Optimize GIF formats:

Gifsicle is a command-line tool for creating, editing, and getting information about GIF images and animations. This stores only the changed portion of each frame, and can radically shrink your GIFs. You can also use transparency to make them even smaller. Gifsicle’s optimizer is pretty powerful, and usually reduces animations to within a couple bytes of the best commercial optimizers.

ImageOptimizer.new('path/to/file.gif').optimize

Optimization Options

Quiet optimization

To have optimization performed in quiet mode without logging progress, an optional quiet parameter may be passed. Default is false.

ImageOptimizer.new('path/to/file.jpg', quiet: true).optimize

You can also enable quiet mode globally:

ImageOptimizer.quiet = true
Lossy JPEG optimization

Pass an optional quality parameter to target a specific lossy JPG quality level (0-100), default is lossless optimization. PNGs will ignore the quality setting.

ImageOptimizer.new('path/to/file.jpg', quality: 80).optimize
Custom PNG optimization quality

By default, optipng is called with the -o7 flag, which controls the level of optimization. This default level generates the most optimized results, at the expense of very high execution times, so you may want to lower it if your server can't handle it.

You can pass an optional level parameter to change this value. the JPEG optimizer will ignore the value.

ImageOptimizer.new('path/to/file.png', level: 3).optimize

Pngquant is called with the '--skip-if-larger', '--speed 1','--force', '--verbose', '--ext .png' flags. This runs pngquant on all png files in the current directory and subdirectory and optimized them in place. Flag '--skip-if-larger' skips images which are smaller. Flag '--ext .png' set custom extension (suffix) for output filename. By default -or8.png or -fs8.png is used.

Don't Remove metadata from PNG

By default, optipng is called with the -strip all flag, which removes all the level of metadata. This default generates the most optimized results.

You can skip removing the meta data by changing the strip_metadata parameter to false. the JPEG optimizer will ignore the value.

ImageOptimizer.new('path/to/file.png', strip_metadata: false).optimize
Custom GIF optimization quality

By default, gifsicle is called with the -O1 flag, which controls the level of optimization. It stores only the changed portion of each image. Other allowed flag are -O2 (Also uses transparency to shrink the file further), -O3 (Try several optimization methods , usually slower, sometimes better results)

You can pass an optional level parameter to change this value. the JPEG optimizer will ignore the value.

ImageOptimizer.new('path/to/file.gif', level: 3).optimize
Use identify

Pass an optional identify parameter to identify file types using ImageMagick or GraphicsMagick identify instead of the filename extension, default is false.

ImageOptimizer.new('path/to/file.jpg', identify: true).optimize

Set bin directories

Optionally set binary directories with the OPTIPNG_BIN, JPEGOPTIM_BIN and IDENTIFY_BIN environment variables.

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request