有人可以解釋一下Photoshop如何將兩個圖像融合在一起，以便在應(yīng)用程序中重現(xiàn)相同的效果。
3 回答
BIG陽
TA貢獻1859條經(jīng)驗 獲得超6個贊
通過在圖像A中的每個像素上對圖像B中的對應(yīng)像素執(zhí)行混合操作，Photoshop將兩個圖像混合在一起。每個像素是一種由多個通道組成的顏色。假設(shè)我們正在處理RGB像素，則每個像素中的通道將是紅色，綠色和藍色。要混合兩個像素，我們混合它們各自的通道。
可以在以下宏中總結(jié)在Photoshop中為每種混合模式發(fā)生的混合操作：
#define ChannelBlend_Normal(A,B) ((uint8)(A))
#define ChannelBlend_Lighten(A,B) ((uint8)((B > A) ? B:A))
#define ChannelBlend_Darken(A,B) ((uint8)((B > A) ? A:B))
#define ChannelBlend_Multiply(A,B) ((uint8)((A * B) / 255))
#define ChannelBlend_Average(A,B) ((uint8)((A + B) / 2))
#define ChannelBlend_Add(A,B) ((uint8)(min(255, (A + B))))
#define ChannelBlend_Subtract(A,B) ((uint8)((A + B < 255) ? 0:(A + B - 255)))
#define ChannelBlend_Difference(A,B) ((uint8)(abs(A - B)))
#define ChannelBlend_Negation(A,B) ((uint8)(255 - abs(255 - A - B)))
#define ChannelBlend_Screen(A,B) ((uint8)(255 - (((255 - A) * (255 - B)) >> 8)))
#define ChannelBlend_Exclusion(A,B) ((uint8)(A + B - 2 * A * B / 255))
#define ChannelBlend_Overlay(A,B) ((uint8)((B < 128) ? (2 * A * B / 255):(255 - 2 * (255 - A) * (255 - B) / 255)))
#define ChannelBlend_SoftLight(A,B) ((uint8)((B < 128)?(2*((A>>1)+64))*((float)B/255):(255-(2*(255-((A>>1)+64))*(float)(255-B)/255))))
#define ChannelBlend_HardLight(A,B) (ChannelBlend_Overlay(B,A))
#define ChannelBlend_ColorDodge(A,B) ((uint8)((B == 255) ? B:min(255, ((A << 8 ) / (255 - B)))))
#define ChannelBlend_ColorBurn(A,B) ((uint8)((B == 0) ? B:max(0, (255 - ((255 - A) << 8 ) / B))))
#define ChannelBlend_LinearDodge(A,B)(ChannelBlend_Add(A,B))
#define ChannelBlend_LinearBurn(A,B) (ChannelBlend_Subtract(A,B))
#define ChannelBlend_LinearLight(A,B)((uint8)(B < 128)?ChannelBlend_LinearBurn(A,(2 * B)):ChannelBlend_LinearDodge(A,(2 * (B - 128))))
#define ChannelBlend_VividLight(A,B) ((uint8)(B < 128)?ChannelBlend_ColorBurn(A,(2 * B)):ChannelBlend_ColorDodge(A,(2 * (B - 128))))
#define ChannelBlend_PinLight(A,B) ((uint8)(B < 128)?ChannelBlend_Darken(A,(2 * B)):ChannelBlend_Lighten(A,(2 * (B - 128))))
#define ChannelBlend_HardMix(A,B) ((uint8)((ChannelBlend_VividLight(A,B) < 128) ? 0:255))
#define ChannelBlend_Reflect(A,B) ((uint8)((B == 255) ? B:min(255, (A * A / (255 - B)))))
#define ChannelBlend_Glow(A,B) (ChannelBlend_Reflect(B,A))
#define ChannelBlend_Phoenix(A,B) ((uint8)(min(A,B) - max(A,B) + 255))
#define ChannelBlend_Alpha(A,B,O) ((uint8)(O * A + (1 - O) * B))
#define ChannelBlend_AlphaF(A,B,F,O) (ChannelBlend_Alpha(F(A,B),A,O))
要混合單個RGB像素，請執(zhí)行以下操作：
ImageTColorR = ChannelBlend_Glow(ImageAColorR, ImageBColorR);
ImageTColorB = ChannelBlend_Glow(ImageAColorB, ImageBColorB);
ImageTColorG = ChannelBlend_Glow(ImageAColorG, ImageBColorG);
ImageTColor = RGB(ImageTColorR, ImageTColorB, ImageTColorG);
如果我們要執(zhí)行具有特定不透明度的混合操作，請說50％：
ImageTColorR = ChannelBlend_AlphaF(ImageAColorR, ImageBColorR, Blend_Subtract, 0.5F);
如果您有指向圖像A，B和T（我們的目標）的圖像數(shù)據(jù)的指針，我們可以使用此宏簡化所有三個通道的混合：
#define ColorBlend_Buffer(T,A,B,M) (T)[0] = ChannelBlend_##M((A)[0], (B)[0]),
(T)[1] = ChannelBlend_##M((A)[1], (B)[1]),
(T)[2] = ChannelBlend_##M((A)[2], (B)[2])
并可以派生以下RGB顏色混合宏：
#define ColorBlend_Normal(T,A,B) (ColorBlend_Buffer(T,A,B,Normal))
#define ColorBlend_Lighten(T,A,B) (ColorBlend_Buffer(T,A,B,Lighten))
#define ColorBlend_Darken(T,A,B) (ColorBlend_Buffer(T,A,B,Darken))
#define ColorBlend_Multiply(T,A,B) (ColorBlend_Buffer(T,A,B,Multiply))
#define ColorBlend_Average(T,A,B) (ColorBlend_Buffer(T,A,B,Average))
#define ColorBlend_Add(T,A,B) (ColorBlend_Buffer(T,A,B,Add))
#define ColorBlend_Subtract(T,A,B) (ColorBlend_Buffer(T,A,B,Subtract))
#define ColorBlend_Difference(T,A,B) (ColorBlend_Buffer(T,A,B,Difference))
#define ColorBlend_Negation(T,A,B) (ColorBlend_Buffer(T,A,B,Negation))
#define ColorBlend_Screen(T,A,B) (ColorBlend_Buffer(T,A,B,Screen))
#define ColorBlend_Exclusion(T,A,B) (ColorBlend_Buffer(T,A,B,Exclusion))
#define ColorBlend_Overlay(T,A,B) (ColorBlend_Buffer(T,A,B,Overlay))
#define ColorBlend_SoftLight(T,A,B) (ColorBlend_Buffer(T,A,B,SoftLight))
#define ColorBlend_HardLight(T,A,B) (ColorBlend_Buffer(T,A,B,HardLight))
#define ColorBlend_ColorDodge(T,A,B) (ColorBlend_Buffer(T,A,B,ColorDodge))
#define ColorBlend_ColorBurn(T,A,B) (ColorBlend_Buffer(T,A,B,ColorBurn))
#define ColorBlend_LinearDodge(T,A,B) (ColorBlend_Buffer(T,A,B,LinearDodge))
#define ColorBlend_LinearBurn(T,A,B) (ColorBlend_Buffer(T,A,B,LinearBurn))
#define ColorBlend_LinearLight(T,A,B) (ColorBlend_Buffer(T,A,B,LinearLight))
#define ColorBlend_VividLight(T,A,B) (ColorBlend_Buffer(T,A,B,VividLight))
#define ColorBlend_PinLight(T,A,B) (ColorBlend_Buffer(T,A,B,PinLight))
#define ColorBlend_HardMix(T,A,B) (ColorBlend_Buffer(T,A,B,HardMix))
#define ColorBlend_Reflect(T,A,B) (ColorBlend_Buffer(T,A,B,Reflect))
#define ColorBlend_Glow(T,A,B) (ColorBlend_Buffer(T,A,B,Glow))
#define ColorBlend_Phoenix(T,A,B) (ColorBlend_Buffer(T,A,B,Phoenix))
例子是：
ColorBlend_Glow(TargetPtr, ImageAPtr, ImageBPtr);
其余的Photoshop混合模式涉及將RGB轉(zhuǎn)換為HLS，然后再次轉(zhuǎn)換。
#define ColorBlend_Hue(T,A,B) ColorBlend_Hls(T,A,B,HueB,LuminationA,SaturationA)
#define ColorBlend_Saturation(T,A,B) ColorBlend_Hls(T,A,B,HueA,LuminationA,SaturationB)
#define ColorBlend_Color(T,A,B) ColorBlend_Hls(T,A,B,HueB,LuminationA,SaturationB)
#define ColorBlend_Luminosity(T,A,B) ColorBlend_Hls(T,A,B,HueA,LuminationB,SaturationA)
#define ColorBlend_Hls(T,A,B,O1,O2,O3) {
float64 HueA, LuminationA, SaturationA;
float64 HueB, LuminationB, SaturationL;
Color_RgbToHls((A)[2],(A)[1],(A)[0], &HueA, &LuminationA, &SaturationA);
Color_RgbToHls((B)[2],(B)[1],(B)[0], &HueB, &LuminationB, &SaturationB);
Color_HlsToRgb(O1,O2,O3,&(T)[2],&(T)[1],&(T)[0]);
}
這些功能將有助于將RGB轉(zhuǎn)換為HLS。
int32 Color_HueToRgb(float64 M1, float64 M2, float64 Hue, float64 *Channel)
{
if (Hue < 0.0)
Hue += 1.0;
else if (Hue > 1.0)
Hue -= 1.0;
if ((6.0 * Hue) < 1.0)
*Channel = (M1 + (M2 - M1) * Hue * 6.0);
else if ((2.0 * Hue) < 1.0)
*Channel = (M2);
else if ((3.0 * Hue) < 2.0)
*Channel = (M1 + (M2 - M1) * ((2.0F / 3.0F) - Hue) * 6.0);
else
*Channel = (M1);
return TRUE;
}
int32 Color_RgbToHls(uint8 Red, uint8 Green, uint8 Blue, float64 *Hue, float64 *Lumination, float64 *Saturation)
{
float64 Delta;
float64 Max, Min;
float64 Redf, Greenf, Bluef;
Redf = ((float64)Red / 255.0F);
Greenf = ((float64)Green / 255.0F);
Bluef = ((float64)Blue / 255.0F);
Max = max(max(Redf, Greenf), Bluef);
Min = min(min(Redf, Greenf), Bluef);
*Hue = 0;
*Lumination = (Max + Min) / 2.0F;
*Saturation = 0;
if (Max == Min)
return TRUE;
Delta = (Max - Min);
if (*Lumination < 0.5)
*Saturation = Delta / (Max + Min);
else
*Saturation = Delta / (2.0 - Max - Min);
if (Redf == Max)
*Hue = (Greenf - Bluef) / Delta;
else if (Greenf == Max)
*Hue = 2.0 + (Bluef - Redf) / Delta;
else
*Hue = 4.0 + (Redf - Greenf) / Delta;
*Hue /= 6.0;
if (*Hue < 0.0)
*Hue += 1.0;
return TRUE;
}
int32 Color_HlsToRgb(float64 Hue, float64 Lumination, float64 Saturation, uint8 *Red, uint8 *Green, uint8 *Blue)
{
float64 M1, M2;
float64 Redf, Greenf, Bluef;
if (Saturation == 0)
{
Redf = Lumination;
Greenf = Lumination;
Bluef = Lumination;
}
else
{
if (Lumination <= 0.5)
M2 = Lumination * (1.0 + Saturation);
else
M2 = Lumination + Saturation - Lumination * Saturation;
M1 = (2.0 * Lumination - M2);
Color_HueToRgb(M1, M2, Hue + (1.0F / 3.0F), &Redf);
Color_HueToRgb(M1, M2, Hue, &Greenf);
Color_HueToRgb(M1, M2, Hue - (1.0F / 3.0F), &Bluef);
}
*Red = (uint8)(Redf * 255);
*Blue = (uint8)(Bluef * 255);
*Green = (uint8)(Greenf * 255);
return TRUE;
}
撒科打諢
TA貢獻1934條經(jīng)驗 獲得超2個贊
此答案中的“色相”，“顏色”，“飽和度”混合模式是錯誤的。沒有Adobe產(chǎn)品轉(zhuǎn)換為HSB，它們直接對RGB值執(zhí)行操作。
例如，這是用于設(shè)置亮度的GLSL：
float lum(vec4 color)
{
return ((0.3 * color.r) + (0.59 * color.g) + (0.11 * color.b));
}
vec4 clipColor(vec4 color)
{
vec4 newColor=color;
float l=lum(color);
float n=min(min(color.r,color.g),color.b);
float x=max(max(color.r,color.g),color.b);
newColor.r=(n<0.0) ? l+(((color.r-l)*l)/(l-n)) : color.r;
newColor.r=(x>1.0) ? l+(((color.r-l)*(1.0-l))/(x-l)) : color.r;
newColor.g=(n<0.0) ? l+(((color.g-l)*l)/(l-n)) : color.g;
newColor.g=(x>1.0) ? l+(((color.g-l)*(1.0-l))/(x-l)) : color.g;
newColor.b=(n<0.0) ? l+(((color.b-l)*l)/(l-n)) : color.b;
newColor.b=(x>1.0) ? l+(((color.b-l)*(1.0-l))/(x-l)) : color.b;
return clamp(newColor,0.0,1.0);
}
vec4 setlum(vec4 color, float l)
{
float d=l-lum(color);
color.r+=d;
color.g+=d;
color.b+=d;
return clipColor(color);
}
kernel vec4 blendLuminosity(sampler topimage, sampler bottomimage)
{
vec4 base=sample(bottomimage, samplerCoord(bottomimage));
vec4 blend=sample(topimage, samplerCoord(topimage));
float bl=lum(blend);
return setlum(base,bl);
}
CIKernels中不支持if .. else語句，因此使用三元運算符。
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