Webp-ffi

Ruby wrapper for libwebp. What is WebP?

WebP is a new image format that provides lossless and lossy compression for images on the web. WebP lossless images are 26% smaller in size compared to PNGs. WebP lossy images are 25-34% smaller in size compared to JPEG images at equivalent SSIM index. WebP supports lossless transparency (also known as alpha channel) with just 22% additional bytes. Transparency is also supported with lossy compression and typically provides 3x smaller file sizes compared to PNG when lossy compression is acceptable for the red/green/blue color channels.

WebP Gallery

Installation

Requirements

First of all you should have install libraries: libpng, libjpeg and libtiff.

For Ubuntu, Debian:

sudo apt-get install libjpeg-dev libpng-dev libtiff-dev

For Mac OS:

brew install libjpg libpng libtiff webp

or (for MacPorts):

sudo port install jpeg libpng tiff

Next, you should install libwebp (if you didn't install it by brew in Mac OS). This gem is not support Windows systems (sorry).

Final part

Add this line to your application's Gemfile:

gem 'webp-ffi'

And then execute:

$ bundle

Or install it yourself as:

$ gem install webp-ffi

Usage

Encoder end Decoder versions

Basic info about libwebp (encoder and decoder versions):

$ irb
2.0.0p0 :001 > require 'webp_ffi'
 => true
2.0.0p0 :002 > WebP.decoder_version
 => "0.3.1"
2.0.0p0 :003 > WebP.encoder_version
 => "0.3.1"

WebP size (width and height)

Get size (width and height) from webp image:

filename = File.expand_path(File.join(File.dirname(__FILE__), "spec/factories/4.webp"))
WebP.webp_size(File.open(filename, "rb").read)
 => [2000, 2353]

Encode WebP image

Encode png, jpg or tiff image to webp:

filename = File.expand_path(File.join(File.dirname(__FILE__), "spec/factories/4.png"))
out_filename = File.expand_path(File.join(File.dirname(__FILE__), "tmp/4.webp"))
WebP.encode(filename, out_filename)

Encode png, jpg or tiff image to webp with options:

WebP.encode(filename, out_filename, quality: 50, resize_w: 100, resize_h: 200)
WebP.encode(filename, out_filename, quality: 75, crop_x: 0, cropt_y: 0, crop_w: 100, crop_h: 100)

Possible encode options:

lossless (int) - Lossless encoding (0=lossy(default), 1=lossless)
quality (float) - between 0 (smallest file) and 100 (biggest)
method (int) - quality/speed trade-off (0=fast, 6=slower-better)
target_size (int) - if non-zero, set the desired target size in bytes. Takes precedence over the 'compression' parameter
target_PSNR (float) - if non-zero, specifies the minimal distortion to try to achieve. Takes precedence over target_size
segments (int) - maximum number of segments to use, in [1..4]
sns_strength (int) - Spatial Noise Shaping. 0=off, 100=maximum
filter_strength (int) - range: [0 = off .. 100 = strongest]
filter_sharpness (int) - range: [0 = off .. 7 = least sharp]
filter_type (int) - filtering type: 0 = simple, 1 = strong (only used if filter_strength > 0 or autofilter > 0)
autofilter (int) - Auto adjust filter's strength [0 = off, 1 = on]
alpha_compression (int) - Algorithm for encoding the alpha plane (0 = none, 1 = compressed with WebP lossless). Default is 1
alpha_filtering (int) - Predictive filtering method for alpha plane. 0: none, 1: fast, 2: best. Default if 1
alpha_quality (int) - Between 0 (smallest size) and 100 (lossless). Default is 100
pass (int) - number of entropy-analysis passes (in [1..10])
show_compressed (int) - if true, export the compressed picture back. In-loop filtering is not applied
preprocessing (int) - preprocessing filter (0=none, 1=segment-smooth)
partitions (int) - log2(number of token partitions) in [0..3]. Default is set to 0 for easier progressive decoding
partition_limit (int) - quality degradation allowed to fit the 512k limit on prediction modes coding (0: no degradation, 100: maximum possible degradation)
width (int), height (int) - Input size (width x height) for YUV
crop_x (int), crop_y (int), crop_w (int), crop_h (int) - crop picture with the given rectangle
resize_w (int), resize_h (int) - resize picture (after any cropping)

Decode WebP image

Decode webp image (default format is png):

filename = File.expand_path(File.join(File.dirname(__FILE__), "spec/factories/4.webp"))
out_filename = File.expand_path(File.join(File.dirname(__FILE__), "tmp/4.png"))
WebP.decode(filename, out_filename)

Decode webp image to pam, ppm, pgm, bmp, tiff or yuv format of image:

filename = File.expand_path(File.join(File.dirname(__FILE__), "spec/factories/4.webp"))
out_filename = File.expand_path(File.join(File.dirname(__FILE__), "tmp/4.png"))
WebP.decode(filename, out_filename, output_format: :pam)
WebP.decode(filename, out_filename, output_format: :ppm)
WebP.decode(filename, out_filename, output_format: :pgm)
WebP.decode(filename, out_filename, output_format: :bmp)
WebP.decode(filename, out_filename, output_format: :tiff)
WebP.decode(filename, out_filename, output_format: :yuv)

Decode webp image with options:

WebP.encode(filename, out_filename, resize_w: 100, resize_h: 200)
WebP.encode(filename, out_filename, crop_x: 0, cropt_y: 0, crop_w: 100, crop_h: 100)

Possible decode options:

bypass_filtering (bool) - disable in-loop filtering
no_fancy_upsampling (bool) - don't use the fancy YUV420 upscaler
use_threads (bool) - use multi-threading
crop_x (int), crop_y (int), crop_w (int), crop_h (int) - crop picture with the given rectangle
resize_w (int), resize_h (int) - resize picture (after any cropping)

Contributing

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