libjpeg-ruby

libjpeg interface for ruby.

Installation

gem 'libjpeg-ruby'

And then execute:

$ bundle

Or install it yourself as:

$ gem install libjpeg-ruby

If you need to specify the libjpeg path, use the following options:

$ gem install libjpeg-ruby -- --with-jpeg-include ~/env/opts/include --with-jpeg-lib ~/env/opts/lib

Usage

decode sample

require 'jpeg'

dec = JPEG::Decoder.new(:pixel_format => :BGR)

p dec.read_header(IO.binread("test.jpg")

raw = dec << IO.binread("test.jpg")
p raw.meta

IO.binwrite("test.bgr", raw)

decode options

option	value type	description
:pixel_format	String or Symbol	output format
:output_gamma	Float	gamma value
:fancy_upsampling	Boolean	T.B.D
:do_smoothing	Boolean	T.B.D
:opt_dither	[strMODE, bool2PASS, intNUM_COLORS]	T.B.D
:use_1ass_quantizer	Boolean	T.B.D
:use_external_colormap	Boolean	T.B.D
:use_2pass_quantizer	Boolean	T.B.D
:without_meta	Boolean	T.B.D
:expand_colormap	Booblean	T.B.D
:scale	Rational or Float	T.B.D
:dct_method	String or Symbol	T.B.D
:with_exif_tags	Boolean	Specify whether to read Exif tag. When set to true, the content of Exif tag will included in the meta information.
:orientation	Boolean	Specify whether to parse Exif orientation. When set to true, apply orientation for decode result.

supported output format

RGB RGB24 YUV422 YUYV RGB565 YUV444 YCbCr BGR BGR24 RGBX RGB32 BGRX BGR32

supported DCT method

ISLOW IFAST FLOAT FASTEST

encode sample

require 'jpeg'

enc = JPEG::Encoder.new(640, 480, :pixel_format => :YCbCr)

IO.binwrite("test.jpg", enc << IO.binread("test.raw"))

encode option

encode options

option	value type	description
:pixel_fromat	String or Symbol	input format
:quality	Integer	encode quality (0-100)
:scale	Rational or Float
:dct_method	String or Symbol	T.B.D
:orientation	Integer	Specify Exif orientation value (1-8).