Improve calculation of brighter colors The old code did not brighten up "pure" colors like "red", "green" and "blue" at all. The new code use a different precomputed LUT which is based upon simplified vector math, see the comments in FbTk/ColorLUT.cc
Mathias Gumz akira at fluxbox dot org
4 files changed,
209 insertions(+),
22 deletions(-)
M
src/FbTk/ColorLUT.cc
→
src/FbTk/ColorLUT.cc
@@ -1,4 +1,4 @@
-// ColorLUT.cc for Fluxbox Window Manager +// ColorLUT.cc for Fluxbox Window Manager // Copyright (c) 2013 - Mathias Gumz <akira at fluxbox dot org> // // Permission is hereby granted, free of charge, to any person obtaining a@@ -22,6 +22,7 @@
#include "ColorLUT.hh" +namespace FbTk { // created by: //@@ -52,8 +53,7 @@
// ./a.out 1.5 | xxd -i -c 8 # value + (value >> 1)) // -namespace FbTk { - +#if 0 // unused const unsigned char ColorLUT::PRE_MULTIPLY_1_5[256] = { 0x00, 0x01, 0x03, 0x04, 0x06, 0x07, 0x09, 0x0a, 0x0c, 0x0d, 0x0f, 0x10, 0x12, 0x13, 0x15, 0x16,@@ -125,6 +125,7 @@ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }; +#endif // ./a.out 0.75 | xxd -i -c 8 # (value >> 1) + (value >> 2)) const unsigned char ColorLUT::PRE_MULTIPLY_0_75[256] = {@@ -161,6 +162,186 @@ 0xae, 0xae, 0xaf, 0xb0, 0xb1, 0xb1, 0xb2, 0xb3,
0xb4, 0xb4, 0xb5, 0xb6, 0xb7, 0xb7, 0xb8, 0xb9, 0xba, 0xba, 0xbb, 0xbc, 0xbd, 0xbd, 0xbe, 0xbf }; + + + +// created by: +// +// #include <math.h> +// #include <stdlib.h> +// #include <unistd.h> +// +// int main(int argc, char const *argv[]) { +// +// size_t i; +// unsigned char c; +// unsigned int v; +// unsigned int s = 4; +// +// if (argc > 1) { +// s = atoi(argv[1]); +// } +// +// for (i = 0; i < 256; ++i) { +// v = i + ((0xff - i) / s); +// c = (unsigned char)v; +// write(1, &c, 1); +// } +// +// return 0; +// } +// +// math behind: +// +// rgb-color-space forms a cube. to make +// something "brighter" one has to nudge a +// given color towards "white" (255, 255, 255). +// we use simple vector math to do this: +// +// (nred ) (red ) ((255) (red )) +// (ngreen) = (green) + s * ((255) - (green)) +// (nblue ) (blue ) ((255) (blue )) +// +// this approach is better than just multiplying +// a given color by a factor (ColorLUT::PRE_MULTIPLY*) +// example: +// +// brighten_via_premultiply_*(#ff0000) = #ff0000 +// brighten_via_brighter_4(#ff0000) = #ffef3f +// +// right now the calculation of 's' is pretty +// straightforward: it is just 1/nth of the length +// of the vector-component. a more precise approach +// would calculate the length of the vector via +// sqrt(red * red + green * green + blue * blue) and +// scale that value down, allthough this would +// need either adhoc-computation or a more advanced +// lookup-table. right now the simple approach is +// sufficient. +// +// to make a color "darker" one has to nudge the +// color towards "black" (0, 0, 0). the formula +// from above changes to +// +// (nred) = (0) + s * ((red) - 0) +// ... +// +// which simplifies down to (s * red) .. which is +// covered by PRE_MULTIPLY_0_75 already. + + +// ./a.out 4 | xxd -i -c 8 +const unsigned char ColorLUT::BRIGHTER_4[256] = { + 0x3f, 0x40, 0x41, 0x42, 0x42, 0x43, 0x44, 0x45, + 0x45, 0x46, 0x47, 0x48, 0x48, 0x49, 0x4a, 0x4b, + 0x4b, 0x4c, 0x4d, 0x4e, 0x4e, 0x4f, 0x50, 0x51, + 0x51, 0x52, 0x53, 0x54, 0x54, 0x55, 0x56, 0x57, + 0x57, 0x58, 0x59, 0x5a, 0x5a, 0x5b, 0x5c, 0x5d, + 0x5d, 0x5e, 0x5f, 0x60, 0x60, 0x61, 0x62, 0x63, + 0x63, 0x64, 0x65, 0x66, 0x66, 0x67, 0x68, 0x69, + 0x69, 0x6a, 0x6b, 0x6c, 0x6c, 0x6d, 0x6e, 0x6f, + 0x6f, 0x70, 0x71, 0x72, 0x72, 0x73, 0x74, 0x75, + 0x75, 0x76, 0x77, 0x78, 0x78, 0x79, 0x7a, 0x7b, + 0x7b, 0x7c, 0x7d, 0x7e, 0x7e, 0x7f, 0x80, 0x81, + 0x81, 0x82, 0x83, 0x84, 0x84, 0x85, 0x86, 0x87, + 0x87, 0x88, 0x89, 0x8a, 0x8a, 0x8b, 0x8c, 0x8d, + 0x8d, 0x8e, 0x8f, 0x90, 0x90, 0x91, 0x92, 0x93, + 0x93, 0x94, 0x95, 0x96, 0x96, 0x97, 0x98, 0x99, + 0x99, 0x9a, 0x9b, 0x9c, 0x9c, 0x9d, 0x9e, 0x9f, + 0x9f, 0xa0, 0xa1, 0xa2, 0xa2, 0xa3, 0xa4, 0xa5, + 0xa5, 0xa6, 0xa7, 0xa8, 0xa8, 0xa9, 0xaa, 0xab, + 0xab, 0xac, 0xad, 0xae, 0xae, 0xaf, 0xb0, 0xb1, + 0xb1, 0xb2, 0xb3, 0xb4, 0xb4, 0xb5, 0xb6, 0xb7, + 0xb7, 0xb8, 0xb9, 0xba, 0xba, 0xbb, 0xbc, 0xbd, + 0xbd, 0xbe, 0xbf, 0xc0, 0xc0, 0xc1, 0xc2, 0xc3, + 0xc3, 0xc4, 0xc5, 0xc6, 0xc6, 0xc7, 0xc8, 0xc9, + 0xc9, 0xca, 0xcb, 0xcc, 0xcc, 0xcd, 0xce, 0xcf, + 0xcf, 0xd0, 0xd1, 0xd2, 0xd2, 0xd3, 0xd4, 0xd5, + 0xd5, 0xd6, 0xd7, 0xd8, 0xd8, 0xd9, 0xda, 0xdb, + 0xdb, 0xdc, 0xdd, 0xde, 0xde, 0xdf, 0xe0, 0xe1, + 0xe1, 0xe2, 0xe3, 0xe4, 0xe4, 0xe5, 0xe6, 0xe7, + 0xe7, 0xe8, 0xe9, 0xea, 0xea, 0xeb, 0xec, 0xed, + 0xed, 0xee, 0xef, 0xf0, 0xf0, 0xf1, 0xf2, 0xf3, + 0xf3, 0xf4, 0xf5, 0xf6, 0xf6, 0xf7, 0xf8, 0xf9, + 0xf9, 0xfa, 0xfb, 0xfc, 0xfc, 0xfd, 0xfe, 0xff +}; + +// ./a.out 8 | xxd -i -c 8 +const unsigned char ColorLUT::BRIGHTER_8[256] = { + 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, + 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, + 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, + 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, + 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, + 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, + 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, + 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, + 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, + 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, + 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, + 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, + 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, + 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, + 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, + 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, + 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, + 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, + 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, + 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, + 0xab, 0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, + 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, + 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, + 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, + 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, + 0xce, 0xcf, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, + 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, + 0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe1, 0xe2, 0xe3, + 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, + 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 0xf0, 0xf1, + 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, + 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff +}; + +#if 0 // unused + +// ./a.out 4 | xxd -i -c 8 +const unsigned char ColorLUT::BRIGHTER_16[256] = { + 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, + 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, + 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, + 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, + 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, + 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, + 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43, + 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, + 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, + 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, + 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, + 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, + 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, + 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, + 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, + 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, + 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, + 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, + 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, + 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, + 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, + 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, + 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb, + 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc1, 0xc2, 0xc3, + 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, + 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd1, 0xd2, + 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, + 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe1, + 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, + 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 0xf0, + 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, + 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff +}; + +#endif + }
M
src/FbTk/ColorLUT.hh
→
src/FbTk/ColorLUT.hh
@@ -24,9 +24,17 @@ namespace FbTk {
namespace ColorLUT { +#if 0 // unused extern const unsigned char PRE_MULTIPLY_1_5[256]; extern const unsigned char PRE_MULTIPLY_1_125[256]; +#endif extern const unsigned char PRE_MULTIPLY_0_75[256]; + +extern const unsigned char BRIGHTER_4[256]; +extern const unsigned char BRIGHTER_8[256]; +#if 0 // unused +extern const unsigned char BRIGHTER_16[256]; +#endif }
M
src/FbTk/Texture.cc
→
src/FbTk/Texture.cc
@@ -37,7 +37,7 @@
namespace { unsigned short inline brighten(unsigned short c) { - return 0x101 * FbTk::ColorLUT::PRE_MULTIPLY_1_5[c]; + return 0x101 * FbTk::ColorLUT::BRIGHTER_8[c]; } unsigned short inline darken(unsigned short c) {
M
src/FbTk/TextureRender.cc
→
src/FbTk/TextureRender.cc
@@ -49,9 +49,9 @@ using std::endl;
using std::string; using std::max; using std::min; -using FbTk::ColorLUT::PRE_MULTIPLY_1_5; -using FbTk::ColorLUT::PRE_MULTIPLY_1_125; using FbTk::ColorLUT::PRE_MULTIPLY_0_75; +using FbTk::ColorLUT::BRIGHTER_4; +using FbTk::ColorLUT::BRIGHTER_8; namespace FbTk {@@ -65,19 +65,17 @@ // use of 'static void function()' here to have
// simple function-pointers for interlace-code // (and avoid *this 'overhead') - // 1.5 of current value, clamp to ~0 (0xff) - static void brighten_1_5(RGBA& color) { - color.r = PRE_MULTIPLY_1_5[color.r]; - color.g = PRE_MULTIPLY_1_5[color.g]; - color.b = PRE_MULTIPLY_1_5[color.b]; - } + static void brighten_4(RGBA& color) { + color.r = BRIGHTER_4[color.r]; + color.g = BRIGHTER_4[color.g]; + color.b = BRIGHTER_4[color.b]; + } - // 1.125 of current value - static void brighten_1_125(RGBA& color) { - color.r = PRE_MULTIPLY_1_125[color.r]; - color.g = PRE_MULTIPLY_1_125[color.g]; - color.b = PRE_MULTIPLY_1_125[color.b]; + static void brighten_8(RGBA& color) { + color.r = BRIGHTER_8[color.r]; + color.g = BRIGHTER_8[color.g]; + color.b = BRIGHTER_8[color.b]; } // 0.75 of old value@@ -93,7 +91,7 @@ static const colorFunc pseudoInterlaceFuncs[2];
}; const RGBA::colorFunc RGBA::pseudoInterlaceFuncs[2] = { - RGBA::brighten_1_125, + RGBA::brighten_4, RGBA::darken };@@ -287,13 +285,13 @@
// brighten top line and first pixel of the // 2nd line for (i = 0; i < width + 1; ++i) { - FbTk::RGBA::brighten_1_5(rgba[i]); + FbTk::RGBA::brighten_4(rgba[i]); } // bright and darken left and right border for (i = 2 * width - 1; i < s - width; i += width) { FbTk::RGBA::darken(rgba[i]); // right border - FbTk::RGBA::brighten_1_5(rgba[i + 1]); // left border on the next line + FbTk::RGBA::brighten_4(rgba[i + 1]); // left border on the next line } // darken bottom line, except the first pixel@@ -331,14 +329,14 @@ size_t i;
// top line, but stop 2 pixels before right border for (i = (width + 1); i < ((2 * width) - 2); i++) { - FbTk::RGBA::brighten_1_5(rgba[i]); + FbTk::RGBA::brighten_4(rgba[i]); } // first darken the right border, then brighten the // left border for ( ; i < (s - (2 * width) - 1); i += width) { FbTk::RGBA::darken(rgba[i]); - FbTk::RGBA::brighten_1_5(rgba[i + 3]); + FbTk::RGBA::brighten_4(rgba[i + 3]); } // bottom line