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Module: stdgo.image.color

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Overview

Package color implements a basic color library.

Index

Variables

import stdgo.image.color.Color
var _sink32:stdgo.GoUInt32
var _sink8:stdgo.GoUInt8
var alpha16Model:stdgo.image.color.Model

Models for the standard color types. 

var alphaModel:stdgo.image.color.Model

Models for the standard color types. 

var black:stdgo.image.color.Gray16

Standard colors. 

var cmykmodel:stdgo.image.color.Model

CMYKModel is the Model for CMYK colors. 

var gray16Model:stdgo.image.color.Model

Models for the standard color types. 

var grayModel:stdgo.image.color.Model

Models for the standard color types. 

var nrgba64model:stdgo.image.color.Model

Models for the standard color types. 

var nrgbamodel:stdgo.image.color.Model

Models for the standard color types. 

var nycbCrAModel:stdgo.image.color.Model

NYCbCrAModel is the Model for non-alpha-premultiplied Y'CbCr-with-alpha colors. 

var opaque:stdgo.image.color.Alpha16

Standard colors. 

var rgba64model:stdgo.image.color.Model

Models for the standard color types. 

var rgbamodel:stdgo.image.color.Model

Models for the standard color types. 

var transparent:stdgo.image.color.Alpha16

Standard colors. 

var white:stdgo.image.color.Gray16

Standard colors. 

var ycbCrModel:stdgo.image.color.Model

YCbCrModel is the Model for Y'CbCr colors.

Functions

import stdgo.image.color.Color

function _alpha16Model

function _alpha16Model(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function _alphaModel

function _alphaModel(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function _cmykModel

function _cmykModel(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function _delta

function _delta(_x:stdgo.GoUInt8, _y:stdgo.GoUInt8):stdgo.GoUInt8

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function _eq

function _eq(_c0:stdgo.image.color.Color, _c1:stdgo.image.color.Color):stdgo.Error

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function _gray16Model

function _gray16Model(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function _grayModel

function _grayModel(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function _nYCbCrAModel

function _nYCbCrAModel(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function _nrgba64Model

function _nrgba64Model(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function _nrgbaModel

function _nrgbaModel(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function _rgba64Model

function _rgba64Model(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function _rgbaModel

function _rgbaModel(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function _sqDiff

function _sqDiff(_x:stdgo.GoUInt32, _y:stdgo.GoUInt32):stdgo.GoUInt32

sqDiff returns the squared-difference of x and y, shifted by 2 so that adding four of those won't overflow a uint32.

x and y are both assumed to be in the range [0, 0xffff].

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function _yCbCrModel

function _yCbCrModel(_c:stdgo.image.color.Color):stdgo.image.color.Color

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function benchmarkNYCbCrAToRGBA

function benchmarkNYCbCrAToRGBA(_b:stdgo.Ref<stdgo.testing.B>):Void

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function benchmarkRGBToYCbCr

function benchmarkRGBToYCbCr(_b:stdgo.Ref<stdgo.testing.B>):Void

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function benchmarkYCbCrToRGB

function benchmarkYCbCrToRGB(_b:stdgo.Ref<stdgo.testing.B>):Void

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function benchmarkYCbCrToRGBA

function benchmarkYCbCrToRGBA(_b:stdgo.Ref<stdgo.testing.B>):Void

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function cmyktoRGB

function cmyktoRGB(_c:stdgo.GoUInt8, _m:stdgo.GoUInt8, _y:stdgo.GoUInt8, _k:stdgo.GoUInt8):{
	_2:stdgo.GoUInt8;
	_1:stdgo.GoUInt8;
	_0:stdgo.GoUInt8;
}

CMYKToRGB converts a CMYK quadruple to an RGB triple.

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function modelFunc

function modelFunc(_f:()):stdgo.image.color.Model

ModelFunc returns a Model that invokes f to implement the conversion.

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function rgbtoCMYK

function rgbtoCMYK(_r:stdgo.GoUInt8, _g:stdgo.GoUInt8, _b:stdgo.GoUInt8):{
	_3:stdgo.GoUInt8;
	_2:stdgo.GoUInt8;
	_1:stdgo.GoUInt8;
	_0:stdgo.GoUInt8;
}

RGBToCMYK converts an RGB triple to a CMYK quadruple.

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function rgbtoYCbCr

function rgbtoYCbCr(_r:stdgo.GoUInt8, _g:stdgo.GoUInt8, _b:stdgo.GoUInt8):{
	_2:stdgo.GoUInt8;
	_1:stdgo.GoUInt8;
	_0:stdgo.GoUInt8;
}

RGBToYCbCr converts an RGB triple to a Y'CbCr triple.

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function testCMYKGray

function testCMYKGray(_t:stdgo.Ref<stdgo.testing.T_>):Void

TestCMYKGray tests that CMYK colors are a superset of Gray colors.

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function testCMYKRoundtrip

function testCMYKRoundtrip(_t:stdgo.Ref<stdgo.testing.T_>):Void

TestCMYKRoundtrip tests that a subset of RGB space can be converted to CMYK and back to within 1/256 tolerance.

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function testCMYKToRGBConsistency

function testCMYKToRGBConsistency(_t:stdgo.Ref<stdgo.testing.T_>):Void

TestCMYKToRGBConsistency tests that calling the RGBA method (16 bit color) then truncating to 8 bits is equivalent to calling the CMYKToRGB function (8 bit color).

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function testNYCbCrAAlpha

function testNYCbCrAAlpha(_t:stdgo.Ref<stdgo.testing.T_>):Void

TestNYCbCrAAlpha tests that NYCbCrA colors are a superset of Alpha colors.

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function testNYCbCrAYCbCr

function testNYCbCrAYCbCr(_t:stdgo.Ref<stdgo.testing.T_>):Void

TestNYCbCrAYCbCr tests that NYCbCrA colors are a superset of YCbCr colors.

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function testPalette

function testPalette(_t:stdgo.Ref<stdgo.testing.T_>):Void

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function testSqDiff

function testSqDiff(_t:stdgo.Ref<stdgo.testing.T_>):Void

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function testYCbCrGray

function testYCbCrGray(_t:stdgo.Ref<stdgo.testing.T_>):Void

TestYCbCrGray tests that YCbCr colors are a superset of Gray colors.

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function testYCbCrRoundtrip

function testYCbCrRoundtrip(_t:stdgo.Ref<stdgo.testing.T_>):Void

TestYCbCrRoundtrip tests that a subset of RGB space can be converted to YCbCr and back to within 2/256 tolerance.

(view code)

function testYCbCrToRGBConsistency

function testYCbCrToRGBConsistency(_t:stdgo.Ref<stdgo.testing.T_>):Void

TestYCbCrToRGBConsistency tests that calling the RGBA method (16 bit color) then truncating to 8 bits is equivalent to calling the YCbCrToRGB function (8 bit color).

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function ycbCrToRGB

function ycbCrToRGB(_y:stdgo.GoUInt8, _cb:stdgo.GoUInt8, _cr:stdgo.GoUInt8):{
	_2:stdgo.GoUInt8;
	_1:stdgo.GoUInt8;
	_0:stdgo.GoUInt8;
}

YCbCrToRGB converts a Y'CbCr triple to an RGB triple.

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Classes

import stdgo.image.color.*

class Alpha

Alpha represents an 8-bit alpha color. 

var a:stdgo.GoUInt8

Alpha function new

function new(?a:stdgo.GoUInt8):Void

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Alpha function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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class Alpha16

Alpha16 represents a 16-bit alpha color. 

var a:stdgo.GoUInt16

Alpha16 function new

function new(?a:stdgo.GoUInt16):Void

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Alpha16 function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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class CMYK

CMYK represents a fully opaque CMYK color, having 8 bits for each of cyan, magenta, yellow and black.

It is not associated with any particular color profile. 

var c:stdgo.GoUInt8
var k:stdgo.GoUInt8
var m:stdgo.GoUInt8
var y:stdgo.GoUInt8

CMYK function new

function new(?c:stdgo.GoUInt8, ?m:stdgo.GoUInt8, ?y:stdgo.GoUInt8, ?k:stdgo.GoUInt8):Void

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CMYK function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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class Gray

Gray represents an 8-bit grayscale color. 

var y:stdgo.GoUInt8

Gray function new

function new(?y:stdgo.GoUInt8):Void

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Gray function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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class Gray16

Gray16 represents a 16-bit grayscale color. 

var y:stdgo.GoUInt16

Gray16 function new

function new(?y:stdgo.GoUInt16):Void

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Gray16 function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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class NRGBA

NRGBA represents a non-alpha-premultiplied 32-bit color. 

var a:stdgo.GoUInt8
var b:stdgo.GoUInt8
var g:stdgo.GoUInt8
var r:stdgo.GoUInt8

NRGBA function new

function new(?r:stdgo.GoUInt8, ?g:stdgo.GoUInt8, ?b:stdgo.GoUInt8, ?a:stdgo.GoUInt8):Void

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NRGBA function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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class NRGBA64

NRGBA64 represents a non-alpha-premultiplied 64-bit color, having 16 bits for each of red, green, blue and alpha. 

var a:stdgo.GoUInt16
var b:stdgo.GoUInt16
var g:stdgo.GoUInt16
var r:stdgo.GoUInt16

NRGBA64 function new

function new(?r:stdgo.GoUInt16, ?g:stdgo.GoUInt16, ?b:stdgo.GoUInt16, ?a:stdgo.GoUInt16):Void

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NRGBA64 function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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class NYCbCrA

NYCbCrA represents a non-alpha-premultiplied Y'CbCr-with-alpha color, having 8 bits each for one luma, two chroma and one alpha component. 

var a:stdgo.GoUInt8
var ycbCr:stdgo.image.color.YCbCr

NYCbCrA function new

function new(?ycbCr:stdgo.image.color.YCbCr, ?a:stdgo.GoUInt8):Void

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NYCbCrA function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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class RGBA

RGBA represents a traditional 32-bit alpha-premultiplied color, having 8 bits for each of red, green, blue and alpha.

An alpha-premultiplied color component C has been scaled by alpha (A), so has valid values 0 \<= C \<= A. 

var a:stdgo.GoUInt8
var b:stdgo.GoUInt8
var g:stdgo.GoUInt8
var r:stdgo.GoUInt8

RGBA function new

function new(?r:stdgo.GoUInt8, ?g:stdgo.GoUInt8, ?b:stdgo.GoUInt8, ?a:stdgo.GoUInt8):Void

(view code)

RGBA function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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class RGBA64

RGBA64 represents a 64-bit alpha-premultiplied color, having 16 bits for each of red, green, blue and alpha.

An alpha-premultiplied color component C has been scaled by alpha (A), so has valid values 0 \<= C \<= A. 

var a:stdgo.GoUInt16
var b:stdgo.GoUInt16
var g:stdgo.GoUInt16
var r:stdgo.GoUInt16

RGBA64 function new

function new(?r:stdgo.GoUInt16, ?g:stdgo.GoUInt16, ?b:stdgo.GoUInt16, ?a:stdgo.GoUInt16):Void

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RGBA64 function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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class YCbCr

YCbCr represents a fully opaque 24-bit Y'CbCr color, having 8 bits each for one luma and two chroma components.

JPEG, VP8, the MPEG family and other codecs use this color model. Such codecs often use the terms YUV and Y'CbCr interchangeably, but strictly speaking, the term YUV applies only to analog video signals, and Y' (luma) is Y (luminance) after applying gamma correction.

Conversion between RGB and Y'CbCr is lossy and there are multiple, slightly different formulae for converting between the two. This package follows the JFIF specification at https://www.w3.org/Graphics/JPEG/jfif3.pdf. 

var cb:stdgo.GoUInt8
var cr:stdgo.GoUInt8
var y:stdgo.GoUInt8

YCbCr function new

function new(?y:stdgo.GoUInt8, ?cb:stdgo.GoUInt8, ?cr:stdgo.GoUInt8):Void

(view code)

YCbCr function rgba

function rgba():{
	_3:stdgo.GoUInt32;
	_2:stdgo.GoUInt32;
	_1:stdgo.GoUInt32;
	_0:stdgo.GoUInt32;
}

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Typedefs

import stdgo.image.color.*

typedef Color

typedef Color = {
	public function rgba():{
		_3:stdgo.GoUInt32;
		_2:stdgo.GoUInt32;
		_1:stdgo.GoUInt32;
		_0:stdgo.GoUInt32;
	};	//  RGBA returns the alpha-premultiplied red, green, blue and alpha values for the color. Each value ranges within [0, 0xffff], but is represented by a uint32 so that multiplying by a blend factor up to 0xffff will not overflow. An alpha-premultiplied color component c has been scaled by alpha (a), so has valid values 0 <= c <= a.
};

Color can convert itself to alpha-premultiplied 16-bits per channel RGBA. The conversion may be lossy.

typedef Model

typedef Model = {
	public function convert(_c:stdgo.image.color.Color):stdgo.image.color.Color;
};

Model can convert any Color to one from its own color model. The conversion may be lossy.

typedef Palette

typedef Palette = stdgo.Slice<stdgo.image.color.Color>;

Palette is a palette of colors.