Aegisub/src/colorspace.cpp

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// Copyright (c) 2005, Niels Martin Hansen, Rodrigo Braz Monteiro
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of the Aegisub Group nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Aegisub Project http://www.aegisub.org/
/// @file colorspace.cpp
/// @brief Functions for converting colours between different representations
/// @ingroup utility
///
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#include "colorspace.h"
#include "utils.h"
static inline unsigned int clip_colorval(int val)
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{
return mid(0, val, 255);
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}
// Algorithm from http://130.113.54.154/~monger/hsl-rgb.html
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void hsl_to_rgb(int H, int S, int L, unsigned char *R, unsigned char *G, unsigned char *B)
{
if (S == 0) {
*R = L;
*G = L;
*B = L;
return;
}
if (L == 128 && S == 255) {
switch (H) {
case 0:
case 255: // actually this is wrong, since this is more like 359 degrees... but it's what you'd expect (sadly :)
*R = 255;
*G = 0;
*B = 0;
return;
case 43:
*R = 255;
*G = 255;
*B = 0;
return;
case 85:
*R = 0;
*G = 255;
*B = 0;
return;
case 128:
*R = 0;
*G = 255;
*B = 255;
return;
case 171:
*R = 0;
*G = 0;
*B = 255;
return;
case 213:
*R = 255;
*G = 0;
*B = 255;
return;
}
}
float h, s, l, r, g, b;
h = H / 255.f;
s = S / 255.f;
l = L / 255.f;
float temp2;
if (l < .5) {
temp2 = l * (1. + s);
} else {
temp2 = l + s - l*s;
}
float temp1 = 2.f * l - temp2;
// assume h is in range [0;1]
float temp3[3];
temp3[0] = h + 1.f/3.f;
if (temp3[0] > 1.f) temp3[0] -= 1.f;
temp3[1] = h;
temp3[2] = h - 1.f/3.f;
if (temp3[2] < 0.f) temp3[2] += 1.f;
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if (6.f * temp3[0] < 1.f)
r = temp1 + (temp2 - temp1) * 6.f * temp3[0];
else if (2.f * temp3[0] < 1.f)
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r = temp2;
else if (3.f * temp3[0] < 2.f)
r = temp1 + (temp2 - temp1) * ((2.f/3.f) - temp3[0]) * 6.f;
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else
r = temp1;
if (6.f * temp3[1] < 1.f)
g = temp1 + (temp2 - temp1) * 6.f * temp3[1];
else if (2.f * temp3[1] < 1.f)
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g = temp2;
else if (3.f * temp3[1] < 2.f)
g = temp1 + (temp2 - temp1) * ((2.f/3.f) - temp3[1]) * 6.f;
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else
g = temp1;
if (6.f * temp3[2] < 1.f)
b = temp1 + (temp2 - temp1) * 6.f * temp3[2];
else if (2.f * temp3[2] < 1.f)
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b = temp2;
else if (3.f * temp3[2] < 2.f)
b = temp1 + (temp2 - temp1) * ((2.f/3.f) - temp3[2]) * 6.f;
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else
b = temp1;
*R = clip_colorval((int)(r*255));
*G = clip_colorval((int)(g*255));
*B = clip_colorval((int)(b*255));
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}
// Formulas taken from wikipedia: http://en.wikipedia.org/wiki/HSV_color_space
// The range for H is 0..255 instead of 0..359, so 60 degrees has been translated to 256/6 here
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void hsv_to_rgb(int H, int S, int V, unsigned char *R, unsigned char *G, unsigned char *B)
{
*R = *G = *B = 0;
// some special cases... oh yeah baby!
if (S == 255) {
switch (H) {
case 0:
case 255: // actually this is wrong, since this is more like 359 degrees... but it's what you'd expect (sadly :)
*R = V;
*G = 0;
*B = 0;
return;
case 43:
*R = V;
*G = V;
*B = 0;
return;
case 85:
*R = 0;
*G = V;
*B = 0;
return;
case 128:
*R = 0;
*G = V;
*B = V;
return;
case 171:
*R = 0;
*G = 0;
*B = V;
return;
case 213:
*R = V;
*G = 0;
*B = V;
return;
}
}
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// Cap values
unsigned int h = H * 360;
unsigned int s = clip_colorval(S)*256;
unsigned int v = clip_colorval(V)*256;
// Saturation is zero, make grey
if (S == 0) {
*R = V;
*G = V;
*B = V;
return;
}
unsigned int r, g, b;
// Else, calculate color
unsigned int Hi = h / 60 / 256;
unsigned int f = h / 60 - Hi * 256;
unsigned int p = v * (65535 - s) / 65536;
unsigned int q = v * (65535 - (f * s)/256) / 65536;
unsigned int t = v * (65535 - ((255 - f) * s)/256) / 65536;
switch (Hi) {
case 0:
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r = v;
g = t;
b = p;
break;
case 1:
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r = q;
g = v;
b = p;
break;
case 2:
r = p;
g = v;
b = t;
break;
case 3:
r = p;
g = q;
b = v;
break;
case 4:
r = t;
g = p;
b = v;
break;
case 5:
default:
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r = v;
g = p;
b = q;
break;
}
*R = clip_colorval(r/256);
*G = clip_colorval(g/256);
*B = clip_colorval(b/256);
}
/// Algorithm from http://130.113.54.154/~monger/hsl-rgb.html
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void rgb_to_hsl(int R, int G, int B, unsigned char *H, unsigned char *S, unsigned char *L)
{
float r = R/255.f, g = G/255.f, b = B/255.f;
float h, s, l;
float maxrgb = std::max(r, std::max(g, b)), minrgb = std::min(r, std::min(g, b));
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l = (minrgb + maxrgb) / 2;
if (minrgb == maxrgb) {
h = 0;
s = 0;
} else {
if (l < 0.5) {
s = (maxrgb - minrgb) / (maxrgb + minrgb);
} else {
s = (maxrgb - minrgb) / (2.f - maxrgb - minrgb);
}
if (r == maxrgb) {
h = (g-b) / (maxrgb-minrgb) + 0;
} else if (g == maxrgb) {
h = (b-r) / (maxrgb-minrgb) + 2;
} else { // if b == maxrgb
h = (r-g) / (maxrgb-minrgb) + 4;
}
}
if (h < 0) h += 6;
if (h >= 6) h -= 6;
*H = clip_colorval(int(h*256/6));
*S = clip_colorval(int(s*255));
*L = clip_colorval(int(l*255));
}
/// Formulas from http://en.wikipedia.org/wiki/HSV_color_space
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void rgb_to_hsv(int R, int G, int B, unsigned char *H, unsigned char *S, unsigned char *V)
{
float r = R/255.f, g = G/255.f, b = B/255.f;
float h, s, v;
float maxrgb = std::max(r, std::max(g, b)), minrgb = std::min(r, std::min(g, b));
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v = maxrgb;
if (maxrgb < .001f) {
s = 1;
} else {
s = (maxrgb - minrgb) / maxrgb;
}
if (minrgb == maxrgb) {
h = 0;
} else if (maxrgb == r) {
h = (g-b) / (maxrgb-minrgb) + 0;
} else if (maxrgb == g) {
h = (b-r) / (maxrgb-minrgb) + 2;
} else { // if maxrgb == b
h = (r-g) / (maxrgb-minrgb) + 4;
}
if (h < 0) h += 6;
if (h >= 6) h -= 6;
*H = clip_colorval(int(h*256/6));
*S = clip_colorval(int(s*255));
*V = clip_colorval(int(v*255));
}
void hsv_to_hsl(int iH, int iS, int iV, unsigned char *oH, unsigned char *oS, unsigned char *oL)
{
int p = iV * (255 - iS);
*oH = iH;
*oL = clip_colorval((p + iV*255)/255/2);
if (*oL == 0) {
*oS = iS; // oS is actually undefined, so any value should work ;)
} else if (*oL <= 128) {
*oS = clip_colorval((iV*255 - p) / (2 * *oL));
} else {
*oS = clip_colorval((iV*255 - p) / (511 - 2 * *oL));
}
}
void hsl_to_hsv(int iH, int iS, int iL, unsigned char *oH, unsigned char *oS, unsigned char *oV)
{
*oH = iH;
if (iS == 0) {
*oS = 0;
*oV = iL;
return;
}
if (iL < 128) {
*oV = iL * (255 + iS) / 255;
*oS = 2 * 255 * iS / (255 + iS);
} else {
*oV = (iL*255 + iS*255 - iL*iS)/255;
*oS = 2 * 255 * iS * (255 - iL) / (iL*255 + iS*255 - iL*iS);
}
}