kernel Color < namespace : "Flame"; vendor : "Adobe"; version : 1; description : "Color blend mode"; > { input image4 dst; input image4 src; output pixel4 result; // PB bytecode can't do functions, use macros to define common functions // gets the max number out of the three #define max3( x, y, z ) ( max((x), max((y), (z))) ) // gets the min number out of the three #define min3( x, y, z ) ( min((x), min((y), (z))) ) // gets the max number out of the three elements in a vector #define max3v(C) ( max3((C.x), (C.y), (C.z)) ) // gets the min number out of the three elements in a vector #define min3v(C) ( min3((C.x), (C.y), (C.z)) ) // Sat - returns float, takes in a pixel3, or pixel4 #define saturation(C) ( (max3((C.r), (C.g), (C.b)) - min3((C.r), (C.g), (C.b))) ) // Luminance - returns float, takes in a pixel3, or pixel4 #define luminance(C) ( (((C.r) * 0.3) + ((C.g) * 0.59) + ((C.b) * 0.11)) ) void evaluatePixel() { pixel4 a = sampleNearest(dst,outCoord()); // cb pixel4 b = sampleNearest(src,outCoord()); // cs // remove premultiplied (srcCP/srcA, dstCP/dstA) pixel3 cb = a.rgb; pixel3 cs = b.rgb; if (a.a > 0.0) { cb.rgb = a.rgb / a.a; } if (b.a > 0.0) { cs.rgb = b.rgb / b.a; } // dstA' = (1-srcA)*dstA + srcA result.a = (1.0-b.a)*a.a + b.a; // adjustment -> adjustedcs float3 adjVec = (cb - cs); float adjustment = luminance(adjVec); float3 adjustedcs = cs + adjustment; // Blend() /* -------------------------------------------------------- * void clipcolor(inout float3 color) * clips color. * input and output float3 color_cl * * -------------------------------------------------------- */ float3 color_cl = adjustedcs; float lum_cl = luminance(color_cl); float3 lumVec = float3(lum_cl, lum_cl, lum_cl); float mini = min3v(color_cl); float maxi = max3v(color_cl); if (mini < 0.0) { mini = lum_cl - mini; // max(..., 0.0000001) prevents divide by 0 color_cl = lumVec + (color_cl - lumVec)*lum_cl/max(mini, 0.0000001); } if (maxi > 1.0) { maxi = maxi - lum_cl; // max(..., 0.0000001) prevents divide by 0 color_cl = lumVec + (color_cl - lumVec)*(1.0 - lum_cl)/max(maxi, 0.0000001); } // end clipcolor - result: color_cl ---------------------- // // dstCP' = (1-srcA)*dstCP + (1-dstA)*srcCP + srcA*dstA*Blend(srcCP/srcA, dstCP/dstA) result.rgb = ((1.0-b.a)*a.rgb) + ((1.0-a.a)*b.rgb) + b.a*a.a*color_cl.rgb; } }