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
This commit is contained in:
Mathias Gumz
parent
c67743d010
commit
e7bfc63932
4 changed files with 209 additions and 22 deletions
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@ -1,4 +1,4 @@
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// ColorLUT.cc for Fluxbox Window Manager
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// ColorLUT.cc for Fluxbox Window Manager
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// Copyright (c) 2013 - Mathias Gumz <akira at fluxbox dot org>
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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@ -22,6 +22,7 @@
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#include "ColorLUT.hh"
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namespace FbTk {
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// created by:
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//
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@ -52,8 +53,7 @@
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// ./a.out 1.5 | xxd -i -c 8 # value + (value >> 1))
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//
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namespace FbTk {
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#if 0 // unused
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const unsigned char ColorLUT::PRE_MULTIPLY_1_5[256] = {
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0x00, 0x01, 0x03, 0x04, 0x06, 0x07, 0x09, 0x0a,
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0x0c, 0x0d, 0x0f, 0x10, 0x12, 0x13, 0x15, 0x16,
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@ -125,6 +125,7 @@ const unsigned char ColorLUT::PRE_MULTIPLY_1_125[256] = {
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0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
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};
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#endif
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// ./a.out 0.75 | xxd -i -c 8 # (value >> 1) + (value >> 2))
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const unsigned char ColorLUT::PRE_MULTIPLY_0_75[256] = {
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@ -162,5 +163,185 @@ const unsigned char ColorLUT::PRE_MULTIPLY_0_75[256] = {
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0xba, 0xba, 0xbb, 0xbc, 0xbd, 0xbd, 0xbe, 0xbf
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};
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// created by:
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//
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// #include <math.h>
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// #include <stdlib.h>
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// #include <unistd.h>
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//
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// int main(int argc, char const *argv[]) {
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//
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// size_t i;
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// unsigned char c;
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// unsigned int v;
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// unsigned int s = 4;
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//
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// if (argc > 1) {
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// s = atoi(argv[1]);
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// }
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//
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// for (i = 0; i < 256; ++i) {
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// v = i + ((0xff - i) / s);
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// c = (unsigned char)v;
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// write(1, &c, 1);
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// }
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//
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// return 0;
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// }
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//
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// math behind:
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//
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// rgb-color-space forms a cube. to make
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// something "brighter" one has to nudge a
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// given color towards "white" (255, 255, 255).
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// we use simple vector math to do this:
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//
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// (nred ) (red ) ((255) (red ))
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// (ngreen) = (green) + s * ((255) - (green))
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// (nblue ) (blue ) ((255) (blue ))
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//
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// this approach is better than just multiplying
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// a given color by a factor (ColorLUT::PRE_MULTIPLY*)
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// example:
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//
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// brighten_via_premultiply_*(#ff0000) = #ff0000
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// brighten_via_brighter_4(#ff0000) = #ffef3f
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//
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// right now the calculation of 's' is pretty
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// straightforward: it is just 1/nth of the length
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// of the vector-component. a more precise approach
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// would calculate the length of the vector via
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// sqrt(red * red + green * green + blue * blue) and
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// scale that value down, allthough this would
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// need either adhoc-computation or a more advanced
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// lookup-table. right now the simple approach is
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// sufficient.
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//
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// to make a color "darker" one has to nudge the
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// color towards "black" (0, 0, 0). the formula
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// from above changes to
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//
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// (nred) = (0) + s * ((red) - 0)
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// ...
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//
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// which simplifies down to (s * red) .. which is
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// covered by PRE_MULTIPLY_0_75 already.
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// ./a.out 4 | xxd -i -c 8
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const unsigned char ColorLUT::BRIGHTER_4[256] = {
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0x3f, 0x40, 0x41, 0x42, 0x42, 0x43, 0x44, 0x45,
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0x45, 0x46, 0x47, 0x48, 0x48, 0x49, 0x4a, 0x4b,
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0x4b, 0x4c, 0x4d, 0x4e, 0x4e, 0x4f, 0x50, 0x51,
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0x51, 0x52, 0x53, 0x54, 0x54, 0x55, 0x56, 0x57,
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0x57, 0x58, 0x59, 0x5a, 0x5a, 0x5b, 0x5c, 0x5d,
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0x5d, 0x5e, 0x5f, 0x60, 0x60, 0x61, 0x62, 0x63,
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0x63, 0x64, 0x65, 0x66, 0x66, 0x67, 0x68, 0x69,
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0x69, 0x6a, 0x6b, 0x6c, 0x6c, 0x6d, 0x6e, 0x6f,
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0x6f, 0x70, 0x71, 0x72, 0x72, 0x73, 0x74, 0x75,
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0x75, 0x76, 0x77, 0x78, 0x78, 0x79, 0x7a, 0x7b,
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0x7b, 0x7c, 0x7d, 0x7e, 0x7e, 0x7f, 0x80, 0x81,
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0x81, 0x82, 0x83, 0x84, 0x84, 0x85, 0x86, 0x87,
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0x87, 0x88, 0x89, 0x8a, 0x8a, 0x8b, 0x8c, 0x8d,
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0x8d, 0x8e, 0x8f, 0x90, 0x90, 0x91, 0x92, 0x93,
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0x93, 0x94, 0x95, 0x96, 0x96, 0x97, 0x98, 0x99,
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0x99, 0x9a, 0x9b, 0x9c, 0x9c, 0x9d, 0x9e, 0x9f,
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0x9f, 0xa0, 0xa1, 0xa2, 0xa2, 0xa3, 0xa4, 0xa5,
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0xa5, 0xa6, 0xa7, 0xa8, 0xa8, 0xa9, 0xaa, 0xab,
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0xab, 0xac, 0xad, 0xae, 0xae, 0xaf, 0xb0, 0xb1,
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0xb1, 0xb2, 0xb3, 0xb4, 0xb4, 0xb5, 0xb6, 0xb7,
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0xb7, 0xb8, 0xb9, 0xba, 0xba, 0xbb, 0xbc, 0xbd,
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0xbd, 0xbe, 0xbf, 0xc0, 0xc0, 0xc1, 0xc2, 0xc3,
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0xc3, 0xc4, 0xc5, 0xc6, 0xc6, 0xc7, 0xc8, 0xc9,
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0xc9, 0xca, 0xcb, 0xcc, 0xcc, 0xcd, 0xce, 0xcf,
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0xcf, 0xd0, 0xd1, 0xd2, 0xd2, 0xd3, 0xd4, 0xd5,
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0xd5, 0xd6, 0xd7, 0xd8, 0xd8, 0xd9, 0xda, 0xdb,
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0xdb, 0xdc, 0xdd, 0xde, 0xde, 0xdf, 0xe0, 0xe1,
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0xe1, 0xe2, 0xe3, 0xe4, 0xe4, 0xe5, 0xe6, 0xe7,
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0xe7, 0xe8, 0xe9, 0xea, 0xea, 0xeb, 0xec, 0xed,
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0xed, 0xee, 0xef, 0xf0, 0xf0, 0xf1, 0xf2, 0xf3,
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0xf3, 0xf4, 0xf5, 0xf6, 0xf6, 0xf7, 0xf8, 0xf9,
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0xf9, 0xfa, 0xfb, 0xfc, 0xfc, 0xfd, 0xfe, 0xff
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};
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// ./a.out 8 | xxd -i -c 8
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const unsigned char ColorLUT::BRIGHTER_8[256] = {
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0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26,
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0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d,
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0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34,
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0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
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0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42,
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0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
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0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50,
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0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,
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0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e,
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0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65,
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0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c,
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0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73,
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0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a,
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0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81,
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0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88,
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0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
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0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96,
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0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d,
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0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4,
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0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab,
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0xab, 0xac, 0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2,
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0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9,
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0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0,
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0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
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0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce,
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0xce, 0xcf, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5,
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0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc,
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0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe1, 0xe2, 0xe3,
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0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
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0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 0xf0, 0xf1,
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0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
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0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
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};
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#if 0 // unused
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// ./a.out 4 | xxd -i -c 8
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const unsigned char ColorLUT::BRIGHTER_16[256] = {
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0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
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0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e,
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0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25,
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0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d,
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0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34,
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0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c,
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0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41, 0x42, 0x43,
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0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b,
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0x4b, 0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52,
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0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a,
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0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61,
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0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
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0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70,
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0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
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0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
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0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
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0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e,
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0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96,
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0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d,
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0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5,
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0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac,
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0xad, 0xae, 0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4,
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0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb,
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0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc1, 0xc2, 0xc3,
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0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca,
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0xcb, 0xcc, 0xcd, 0xce, 0xcf, 0xd0, 0xd1, 0xd2,
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0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9,
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0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe1,
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0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8,
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0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 0xf0,
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0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
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0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
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};
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#endif
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}
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@ -24,10 +24,18 @@ namespace FbTk {
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namespace ColorLUT {
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#if 0 // unused
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extern const unsigned char PRE_MULTIPLY_1_5[256];
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extern const unsigned char PRE_MULTIPLY_1_125[256];
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#endif
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extern const unsigned char PRE_MULTIPLY_0_75[256];
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extern const unsigned char BRIGHTER_4[256];
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extern const unsigned char BRIGHTER_8[256];
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#if 0 // unused
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extern const unsigned char BRIGHTER_16[256];
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#endif
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}
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}
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@ -37,7 +37,7 @@
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namespace {
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unsigned short inline brighten(unsigned short c) {
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return 0x101 * FbTk::ColorLUT::PRE_MULTIPLY_1_5[c];
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return 0x101 * FbTk::ColorLUT::BRIGHTER_8[c];
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}
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unsigned short inline darken(unsigned short c) {
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@ -49,9 +49,9 @@ using std::endl;
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using std::string;
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using std::max;
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using std::min;
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using FbTk::ColorLUT::PRE_MULTIPLY_1_5;
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using FbTk::ColorLUT::PRE_MULTIPLY_1_125;
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using FbTk::ColorLUT::PRE_MULTIPLY_0_75;
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using FbTk::ColorLUT::BRIGHTER_4;
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using FbTk::ColorLUT::BRIGHTER_8;
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namespace FbTk {
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@ -65,19 +65,17 @@ struct RGBA {
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// simple function-pointers for interlace-code
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// (and avoid *this 'overhead')
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// 1.5 of current value, clamp to ~0 (0xff)
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static void brighten_1_5(RGBA& color) {
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color.r = PRE_MULTIPLY_1_5[color.r];
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color.g = PRE_MULTIPLY_1_5[color.g];
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color.b = PRE_MULTIPLY_1_5[color.b];
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static void brighten_4(RGBA& color) {
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color.r = BRIGHTER_4[color.r];
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color.g = BRIGHTER_4[color.g];
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color.b = BRIGHTER_4[color.b];
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}
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// 1.125 of current value
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static void brighten_1_125(RGBA& color) {
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color.r = PRE_MULTIPLY_1_125[color.r];
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color.g = PRE_MULTIPLY_1_125[color.g];
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color.b = PRE_MULTIPLY_1_125[color.b];
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static void brighten_8(RGBA& color) {
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color.r = BRIGHTER_8[color.r];
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color.g = BRIGHTER_8[color.g];
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color.b = BRIGHTER_8[color.b];
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}
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// 0.75 of old value
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@ -93,7 +91,7 @@ struct RGBA {
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};
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const RGBA::colorFunc RGBA::pseudoInterlaceFuncs[2] = {
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RGBA::brighten_1_125,
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RGBA::brighten_4,
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RGBA::darken
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};
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@ -287,13 +285,13 @@ void renderBevel1(bool interlaced,
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// brighten top line and first pixel of the
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// 2nd line
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for (i = 0; i < width + 1; ++i) {
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FbTk::RGBA::brighten_1_5(rgba[i]);
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FbTk::RGBA::brighten_4(rgba[i]);
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}
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// bright and darken left and right border
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for (i = 2 * width - 1; i < s - width; i += width) {
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FbTk::RGBA::darken(rgba[i]); // right border
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FbTk::RGBA::brighten_1_5(rgba[i + 1]); // left border on the next line
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FbTk::RGBA::brighten_4(rgba[i + 1]); // left border on the next line
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}
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// darken bottom line, except the first pixel
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@ -331,14 +329,14 @@ void renderBevel2(bool interlaced,
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// top line, but stop 2 pixels before right border
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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
|
||||
|
|
|
|||
Loading…
Reference in a new issue