实现photoshop 颜色混合的shader

2024-01-05 19:58
文章标签 实现 photoshop shader 颜色混合

本文主要是介绍实现photoshop 颜色混合的shader，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

这个过程很是艰辛呐！

国内博客查找到的说明基本上都是这样
颜色模式：

是采用底色的亮度以及绘图色的色相、饱和度来创建最终色。它可保护原图的灰阶层次，对于图像的色彩微调、给单色和彩色图像着色都非常有用。
Color 颜色
HcScYc =HASAYB
输出图像的亮度为下层，色调和饱和度保持为上层

甚至wiki说明也是这样：

The Color blend mode preserves the luma of the bottom layer, while adopting the hue and chroma of the top layer.

我费心的去了解查找HSL，HSV到RGB之前的转化，并去验证转化是否有错误。总之最后结果都不对！
最后通过颜色坐标系在线转化工具colorizer发现颜色混合并不是像上面说的那样计算。

查找photoshop混合的文档，但是没有找到文档,自己控制单一变量记录混合后的值，甚至想学用matlab绘制函数曲线。

下班终于找到一个老外跟我遇到相同的问题了，Fuck呀。

  • It does not convert both images to the YUV colourspace, then combine the Y (luminance) channel of one image with the U and V (chrominance) channels of the second. 根本不需要YUV转换

  • It does not involve a similar transformation/combination in the HSL (hue/saturation/lightness), or HSV (hue/saturation/value) colourspaces[1].根本不需要HSL或HSV转换

  • In fact, it does not involve a simple combination of one channel from one image with the other channels of a second image in any standard colorspace.根本不需要图像在任何标准颜色坐标系中颜色通道的转换

我之前把无关HSV HSL颜色转化的的答案都过滤掉了，事实上那些才是正确的。

Adobe’s PDF specification (specifically, PDF Blend Modes: Addendum) describes the colour blend mode as a set of three functions, which I’ve paraphrased here as pseudocode (but not the same pseudocode as in the original document), with pixel being a struct of three floating point values (Red, Green, and Blue)

float Lum(pixel colour){return (colour.Red * 0.3) + (colour.Green * 0.59) + (colour.Blue * 0.11);}pixel ClipColour(pixel colour){pixel result;float luminance = Lum(colour);float cMin = min(colour.Red, colour.Green, colour.Blue);float cMax = max(colour.Red, colour.Green, colour.Blue);if (cMin < 0.0){result.Red = luminance + (((colour.Red - luminance) * luminance) / (luminance - cMin));result.Green = luminance + (((colour.Green - luminance) * luminance) / (luminance - cMin));result.Blue = luminance + (((colour.Blue - luminance) * luminance) / (luminance - cMin));}if (cMax > 1.0){result.Red = luminance + (((colour.Red - luminance) * (1.0 - luminance)) / (cMax - luminance));result.Green = luminance + (((colour.Green - luminance) * (1.0 - luminance)) / (cMax - luminance));result.Blue = luminance + (((colour.Blue - luminance) * (1.0 - luminance)) / (cMax - luminance));}return result;}pixel SetLum(pixel colour, float luminance){pixel result;float diff = luminance - Lum(colour);result.Red = colour.Red + diff;result.Green = colour.Green + diff;result.Blue = colour.Blue + diff;return ClipColour(color);
//注:这里应该是ClipColour(result)}

我改成了python的便于查看数值正确性:

class vec3:r=0g=0b=0def __init__(self,*para):self.r = 0self.g = 0self .b =0pLen = len(para)if pLen > 0:self.r = para[0]if pLen > 1:self.g = para[1]if pLen > 2:self.b = para[2]def __str__(self):return '['+str(self.r) + " " + str(self.g) + " "+ str(self.b)+']'def toNormal(self):self.r = self.r/255.0self.g = self.g/255.0self.b = self.b/255.0return selfdef toRGB(self):self.r = int(self.r*255.0)self.g = int(self.g*255.0)self.b = int(self.b*255.0)return selfdef lumF(color):return (color.r * 0.3) + (color.g * 0.59) + (color.b * 0.11)def clipColourVec3(color):result = colorluminance = lumF(color)cMin = min(color.r, color.g, color.b)cMax = max(color.r, color.g, color.b)if cMin < 0.0:result.r = luminance + (((color.r - luminance) * luminance) / (luminance - cMin))result.g = luminance + (((color.g - luminance) * luminance) / (luminance - cMin))result.b = luminance + (((color.b - luminance) * luminance) / (luminance - cMin))if cMax > 1.0:result.r = luminance + (((color.r - luminance) * (1.0 - luminance)) / (cMax - luminance))result.g = luminance + (((color.g - luminance) * (1.0 - luminance)) / (cMax - luminance))result.b = luminance + (((color.b - luminance) * (1.0 - luminance)) / (cMax - luminance))return result.toRGB()def colorBlend(colorFront,colorBack):result = vec3(0)frontLum = lumF(colorFront)backLum = lumF(colorBack) diff = backLum - frontLumresult.r = colorFront.r + diffresult.g = colorFront.g + diffresult.b = colorFront.b + diffreturn clipColourVec3(result)colorFront = vec3(198,169,79).toNormal()
colorBack = vec3(70,90,163).toNormal()finalBlend = colorBlend(colorFront,colorBack)
print finalBlend

附老外很久以前实现的ps上的混合shader,有些可能已经跟当前效果对不上了。比如该篇博客color blend

** Copyright (c) 2012, Romain Dura romain@shazbits.com
** 
** Permission to use, copy, modify, and/or distribute this software for any 
** purpose with or without fee is hereby granted, provided that the above 
** copyright notice and this permission notice appear in all copies.
** 
** THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 
** WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 
** MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 
** SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 
** WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 
** ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR 
** IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*//*
** Photoshop & misc math
** Blending modes, RGB/HSL/Contrast/Desaturate, levels control
**
** Romain Dura | Romz
** Blog: http://mouaif.wordpress.com
** Post: http://mouaif.wordpress.com/?p=94
*//*
** Desaturation
*/vec4 Desaturate(vec3 color, float Desaturation)
{vec3 grayXfer = vec3(0.3, 0.59, 0.11);vec3 gray = vec3(dot(grayXfer, color));return vec4(mix(color, gray, Desaturation), 1.0);
}/*
** Hue, saturation, luminance
*/vec3 RGBToHSL(vec3 color)
{vec3 hsl; // init to 0 to avoid warnings ? (and reverse if + remove first part)float fmin = min(min(color.r, color.g), color.b);    //Min. value of RGBfloat fmax = max(max(color.r, color.g), color.b);    //Max. value of RGBfloat delta = fmax - fmin;             //Delta RGB valuehsl.z = (fmax + fmin) / 2.0; // Luminanceif (delta == 0.0)       //This is a gray, no chroma...{hsl.x = 0.0;    // Huehsl.y = 0.0;    // Saturation}else                                    //Chromatic data...{if (hsl.z < 0.5)hsl.y = delta / (fmax + fmin); // Saturationelsehsl.y = delta / (2.0 - fmax - fmin); // Saturationfloat deltaR = (((fmax - color.r) / 6.0) + (delta / 2.0)) / delta;float deltaG = (((fmax - color.g) / 6.0) + (delta / 2.0)) / delta;float deltaB = (((fmax - color.b) / 6.0) + (delta / 2.0)) / delta;if (color.r == fmax )hsl.x = deltaB - deltaG; // Hueelse if (color.g == fmax)hsl.x = (1.0 / 3.0) + deltaR - deltaB; // Hueelse if (color.b == fmax)hsl.x = (2.0 / 3.0) + deltaG - deltaR; // Hueif (hsl.x < 0.0)hsl.x += 1.0; // Hueelse if (hsl.x > 1.0)hsl.x -= 1.0; // Hue}return hsl;
}float HueToRGB(float f1, float f2, float hue)
{if (hue < 0.0)hue += 1.0;else if (hue > 1.0)hue -= 1.0;float res;if ((6.0 * hue) < 1.0)res = f1 + (f2 - f1) * 6.0 * hue;else if ((2.0 * hue) < 1.0)res = f2;else if ((3.0 * hue) < 2.0)res = f1 + (f2 - f1) * ((2.0 / 3.0) - hue) * 6.0;elseres = f1;return res;
}vec3 HSLToRGB(vec3 hsl)
{vec3 rgb;if (hsl.y == 0.0)rgb = vec3(hsl.z); // Luminanceelse{float f2;if (hsl.z < 0.5)f2 = hsl.z * (1.0 + hsl.y);elsef2 = (hsl.z + hsl.y) - (hsl.y * hsl.z);float f1 = 2.0 * hsl.z - f2;rgb.r = HueToRGB(f1, f2, hsl.x + (1.0/3.0));rgb.g = HueToRGB(f1, f2, hsl.x);rgb.b= HueToRGB(f1, f2, hsl.x - (1.0/3.0));}return rgb;
}/*
** Contrast, saturation, brightness
** Code of this function is from TGM's shader pack
** http://irrlicht.sourceforge.net/phpBB2/viewtopic.php?t=21057
*/// For all settings: 1.0 = 100% 0.5=50% 1.5 = 150%
vec3 ContrastSaturationBrightness(vec3 color, float brt, float sat, float con)
{// Increase or decrease theese values to adjust r, g and b color channels seperatelyconst float AvgLumR = 0.5;const float AvgLumG = 0.5;const float AvgLumB = 0.5;const vec3 LumCoeff = vec3(0.2125, 0.7154, 0.0721);vec3 AvgLumin = vec3(AvgLumR, AvgLumG, AvgLumB);vec3 brtColor = color * brt;vec3 intensity = vec3(dot(brtColor, LumCoeff));vec3 satColor = mix(intensity, brtColor, sat);vec3 conColor = mix(AvgLumin, satColor, con);return conColor;
}/*
** Float blending modes
** Adapted from here: http://www.nathanm.com/photoshop-blending-math/
** But I modified the HardMix (wrong condition), Overlay, SoftLight, ColorDodge, ColorBurn, VividLight, PinLight (inverted layers) ones to have correct results
*/#define BlendLinearDodgef           BlendAddf
#define BlendLinearBurnf            BlendSubstractf
#define BlendAddf(base, blend)      min(base + blend, 1.0)
#define BlendSubstractf(base, blend)    max(base + blend - 1.0, 0.0)
#define BlendLightenf(base, blend)      max(blend, base)
#define BlendDarkenf(base, blend)       min(blend, base)
#define BlendLinearLightf(base, blend)  (blend < 0.5 ? BlendLinearBurnf(base, (2.0 * blend)) : BlendLinearDodgef(base, (2.0 * (blend - 0.5))))
#define BlendScreenf(base, blend)       (1.0 - ((1.0 - base) * (1.0 - blend)))
#define BlendOverlayf(base, blend)  (base < 0.5 ? (2.0 * base * blend) : (1.0 - 2.0 * (1.0 - base) * (1.0 - blend)))
#define BlendSoftLightf(base, blend)    ((blend < 0.5) ? (2.0 * base * blend + base * base * (1.0 - 2.0 * blend)) : (sqrt(base) * (2.0 * blend - 1.0) + 2.0 * base * (1.0 - blend)))
#define BlendColorDodgef(base, blend)   ((blend == 1.0) ? blend : min(base / (1.0 - blend), 1.0))
#define BlendColorBurnf(base, blend)    ((blend == 0.0) ? blend : max((1.0 - ((1.0 - base) / blend)), 0.0))
#define BlendVividLightf(base, blend)   ((blend < 0.5) ? BlendColorBurnf(base, (2.0 * blend)) : BlendColorDodgef(base, (2.0 * (blend - 0.5))))
#define BlendPinLightf(base, blend)     ((blend < 0.5) ? BlendDarkenf(base, (2.0 * blend)) : BlendLightenf(base, (2.0 *(blend - 0.5))))
#define BlendHardMixf(base, blend)  ((BlendVividLightf(base, blend) < 0.5) ? 0.0 : 1.0)
#define BlendReflectf(base, blend)      ((blend == 1.0) ? blend : min(base * base / (1.0 - blend), 1.0))/*
** Vector3 blending modes
*/// Component wise blending
#define Blend(base, blend, funcf)       vec3(funcf(base.r, blend.r), funcf(base.g, blend.g), funcf(base.b, blend.b))#define BlendNormal(base, blend)        (blend)
#define BlendLighten                BlendLightenf
#define BlendDarken             BlendDarkenf
#define BlendMultiply(base, blend)      (base * blend)
#define BlendAverage(base, blend)       ((base + blend) / 2.0)
#define BlendAdd(base, blend)       min(base + blend, vec3(1.0))
#define BlendSubstract(base, blend)     max(base + blend - vec3(1.0), vec3(0.0))
#define BlendDifference(base, blend)    abs(base - blend)
#define BlendNegation(base, blend)  (vec3(1.0) - abs(vec3(1.0) - base - blend))
#define BlendExclusion(base, blend)     (base + blend - 2.0 * base * blend)
#define BlendScreen(base, blend)        Blend(base, blend, BlendScreenf)
#define BlendOverlay(base, blend)       Blend(base, blend, BlendOverlayf)
#define BlendSoftLight(base, blend)     Blend(base, blend, BlendSoftLightf)
#define BlendHardLight(base, blend)     BlendOverlay(blend, base)
#define BlendColorDodge(base, blend)    Blend(base, blend, BlendColorDodgef)
#define BlendColorBurn(base, blend)     Blend(base, blend, BlendColorBurnf)
#define BlendLinearDodge            BlendAdd
#define BlendLinearBurn         BlendSubstract
// Linear Light is another contrast-increasing mode
// If the blend color is darker than midgray, Linear Light darkens the image by decreasing the brightness. If the blend color is lighter than midgray, the result is a brighter image due to increased brightness.
#define BlendLinearLight(base, blend)   Blend(base, blend, BlendLinearLightf)
#define BlendVividLight(base, blend)    Blend(base, blend, BlendVividLightf)
#define BlendPinLight(base, blend)      Blend(base, blend, BlendPinLightf)
#define BlendHardMix(base, blend)       Blend(base, blend, BlendHardMixf)
#define BlendReflect(base, blend)       Blend(base, blend, BlendReflectf)
#define BlendGlow(base, blend)      BlendReflect(blend, base)
#define BlendPhoenix(base, blend)       (min(base, blend) - max(base, blend) + vec3(1.0))
#define BlendOpacity(base, blend, F, O)     (F(base, blend) * O + blend * (1.0 - O))// Hue Blend mode creates the result color by combining the luminance and saturation of the base color with the hue of the blend color.
vec3 BlendHue(vec3 base, vec3 blend)
{vec3 baseHSL = RGBToHSL(base);return HSLToRGB(vec3(RGBToHSL(blend).r, baseHSL.g, baseHSL.b));
}// Saturation Blend mode creates the result color by combining the luminance and hue of the base color with the saturation of the blend color.
vec3 BlendSaturation(vec3 base, vec3 blend)
{vec3 baseHSL = RGBToHSL(base);return HSLToRGB(vec3(baseHSL.r, RGBToHSL(blend).g, baseHSL.b));
}// Color Mode keeps the brightness of the base color and applies both the hue and saturation of the blend color.
vec3 BlendColor(vec3 base, vec3 blend)
{vec3 blendHSL = RGBToHSL(blend);return HSLToRGB(vec3(blendHSL.r, blendHSL.g, RGBToHSL(base).b));
}// Luminosity Blend mode creates the result color by combining the hue and saturation of the base color with the luminance of the blend color.
vec3 BlendLuminosity(vec3 base, vec3 blend)
{vec3 baseHSL = RGBToHSL(base);return HSLToRGB(vec3(baseHSL.r, baseHSL.g, RGBToHSL(blend).b));
}/*
** Gamma correction
** Details: http://blog.mouaif.org/2009/01/22/photoshop-gamma-correction-shader/
*/#define GammaCorrection(color, gamma)                               pow(color, 1.0 / gamma)/*
** Levels control (input (+gamma), output)
** Details: http://blog.mouaif.org/2009/01/28/levels-control-shader/
*/#define LevelsControlInputRange(color, minInput, maxInput)              min(max(color - vec3(minInput), vec3(0.0)) / (vec3(maxInput) - vec3(minInput)), vec3(1.0))
#define LevelsControlInput(color, minInput, gamma, maxInput)                GammaCorrection(LevelsControlInputRange(color, minInput, maxInput), gamma)
#define LevelsControlOutputRange(color, minOutput, maxOutput)           mix(vec3(minOutput), vec3(maxOutput), color)
#define LevelsControl(color, minInput, gamma, maxInput, minOutput, maxOutput)   LevelsControlOutputRange(LevelsControlInput(color, minInput, gamma, maxInput), minOutput, maxOutput)

Over，道路曲折希望遇到该问题的人少走弯路。

参考链接:
1. Secrets_of_Photoshops_Colour_Blend
2. photoshops-color-blend-mode
3. 我的小屋

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http://www.chinasem.cn/article/573996。

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