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applied a modified version of a patch by Gautier Portet that introduces a

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2005-03-26  Sven Neumann  <sven@gimp.org>

	* modules/cdisplay_colorblind.c: applied a modified version of
	a patch by Gautier Portet that introduces a LUT for the gamma
	correction (bug #101256). Also moved constants out of the
	CdisplayColorblind struct.
This commit is contained in:
Sven Neumann
2005-03-26 00:53:56 +00:00
committed by Sven Neumann
parent 222226c576
commit 8d2ca845fd
2 changed files with 84 additions and 79 deletions
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156
modules/cdisplay_colorblind.c
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@ -92,15 +92,12 @@ struct _CdisplayColorblind
ColorblindDeficiency deficiency;
gfloat rgb2lms[9];
gfloat lms2rgb[9];
gfloat gammaRGB[3];
gfloat a1, b1, c1;
gfloat a2, b2, c2;
gfloat inflection;
guint32 cache[2 * COLOR_CACHE_SIZE];
gfloat gamma_lut[256][3];
};
struct _CdisplayColorblindClass
@ -141,6 +138,62 @@ static void cdisplay_colorblind_changed (GimpColorDisplay *dis
static void cdisplay_colorblind_set_deficiency (CdisplayColorblind *colorblind,
ColorblindDeficiency value);
/* The RGB<->LMS transforms above are computed from the human cone
* photo-pigment absorption spectra and the monitor phosphor
* emission spectra. These parameters are fairly constant for most
* humans and most montiors (at least for modern CRTs). However,
* gamma will vary quite a bit, as it is a property of the monitor
* (eg. amplifier gain), the video card, and even the
* software. Further, users can adjust their gammas (either via
* adjusting the monitor amp gains or in software). That said, the
* following are the gamma estimates that we have used in the
* Vischeck code. Many colorblind users have viewed our simulations
* and told us that they "work" (simulated and original images are
* indistinguishabled).
*/
static const gfloat gammaRGB[3] = { 2.1, 2.0, 2.1 };
/* For most modern Cathode-Ray Tube monitors (CRTs), the following
* are good estimates of the RGB->LMS and LMS->RGB transform
* matrices. They are based on spectra measured on a typical CRT
* with a PhotoResearch PR650 spectral photometer and the Stockman
* human cone fundamentals. NOTE: these estimates will NOT work well
* for LCDs!
*/
static const gfloat rgb2lms[9] =
{
0.05059983,
0.08585369,
0.00952420,
0.01893033,
0.08925308,
0.01370054,
0.00292202,
0.00975732,
0.07145979
};
static const gfloat lms2rgb[9] =
{
30.830854,
-29.832659,
1.610474,
-6.481468,
17.715578,
-2.532642,
-0.375690,
-1.199062,
14.273846
};
static const GimpModuleInfo cdisplay_colorblind_info =
{
GIMP_MODULE_ABI_VERSION,
@ -244,53 +297,14 @@ cdisplay_colorblind_class_init (CdisplayColorblindClass *klass)
static void
cdisplay_colorblind_init (CdisplayColorblind *colorblind)
{
/* For most modern Cathode-Ray Tube monitors (CRTs), the following
* are good estimates of the RGB->LMS and LMS->RGB transform
* matrices. They are based on spectra measured on a typical CRT
* with a PhotoResearch PR650 spectral photometer and the Stockman
* human cone fundamentals. NOTE: these estimates will NOT work well
* for LCDs!
*/
colorblind->rgb2lms[0] = 0.05059983;
colorblind->rgb2lms[1] = 0.08585369;
colorblind->rgb2lms[2] = 0.00952420;
gint i;
colorblind->rgb2lms[3] = 0.01893033;
colorblind->rgb2lms[4] = 0.08925308;
colorblind->rgb2lms[5] = 0.01370054;
colorblind->rgb2lms[6] = 0.00292202;
colorblind->rgb2lms[7] = 0.00975732;
colorblind->rgb2lms[8] = 0.07145979;
colorblind->lms2rgb[0] = 30.830854;
colorblind->lms2rgb[1] = -29.832659;
colorblind->lms2rgb[2] = 1.610474;
colorblind->lms2rgb[3] = -6.481468;
colorblind->lms2rgb[4] = 17.715578;
colorblind->lms2rgb[5] = -2.532642;
colorblind->lms2rgb[6] = -0.375690;
colorblind->lms2rgb[7] = -1.199062;
colorblind->lms2rgb[8] = 14.273846;
/* The RGB<->LMS transforms above are computed from the human cone
* photo-pigment absorption spectra and the monitor phosphor
* emission spectra. These parameters are fairly constant for most
* humans and most montiors (at least for modern CRTs). However,
* gamma will vary quite a bit, as it is a property of the monitor
* (eg. amplifier gain), the video card, and even the
* software. Further, users can adjust their gammas (either via
* adjusting the monitor amp gains or in software). That said, the
* following are the gamma estimates that we have used in the
* Vischeck code. Many colorblind users have viewed our simulations
* and told us that they "work" (simulated and original images are
* indistinguishabled).
*/
colorblind->gammaRGB[0] = 2.1;
colorblind->gammaRGB[1] = 2.0;
colorblind->gammaRGB[2] = 2.1;
for (i = 0; i < 256; i++)
{
colorblind->gamma_lut[i][0] = pow (i, 1.0 / gammaRGB[0]);
colorblind->gamma_lut[i][1] = pow (i, 1.0 / gammaRGB[1]);
colorblind->gamma_lut[i][2] = pow (i, 1.0 / gammaRGB[2]);
}
}
static void
@ -342,7 +356,6 @@ cdisplay_colorblind_convert (GimpColorDisplay *display,
{
CdisplayColorblind *colorblind = CDISPLAY_COLORBLIND (display);
guchar *b;
gfloat rgb2lms[9],lms2rgb[9];
gfloat a1, b1, c1, a2, b2, c2;
gfloat tmp;
gfloat red, green, blue, redOld, greenOld;
@ -352,9 +365,6 @@ cdisplay_colorblind_convert (GimpColorDisplay *display,
if (bpp != 3)
return;
/* to improve readability, copy the parameters into local variables */
memcpy (rgb2lms, colorblind->rgb2lms, sizeof (rgb2lms));
memcpy (lms2rgb, colorblind->lms2rgb, sizeof (lms2rgb));
a1 = colorblind->a1; b1 = colorblind->b1; c1 = colorblind->c1;
a2 = colorblind->a2; b2 = colorblind->b2; c2 = colorblind->c2;
@ -379,14 +389,10 @@ cdisplay_colorblind_convert (GimpColorDisplay *display,
continue;
}
red = b[0];
green = b[1];
blue = b[2];
/* Remove gamma to linearize RGB intensities */
red = pow (red, 1.0 / colorblind->gammaRGB[0]);
green = pow (green, 1.0 / colorblind->gammaRGB[1]);
blue = pow (blue, 1.0 / colorblind->gammaRGB[2]);
red = colorblind->gamma_lut[b[0]][0];
green = colorblind->gamma_lut[b[1]][1];
blue = colorblind->gamma_lut[b[2]][2];
/* Convert to LMS (dot product with transform matrix) */
redOld = red;
@ -438,20 +444,15 @@ cdisplay_colorblind_convert (GimpColorDisplay *display,
blue = redOld * lms2rgb[6] + greenOld * lms2rgb[7] + blue * lms2rgb[8];
/* Apply gamma to go back to non-linear intensities */
red = pow (red, colorblind->gammaRGB[0]);
green = pow (green, colorblind->gammaRGB[1]);
blue = pow (blue, colorblind->gammaRGB[2]);
red = pow (red, gammaRGB[0]);
green = pow (green, gammaRGB[1]);
blue = pow (blue, gammaRGB[2]);
/* Ensure that we stay within the RGB gamut */
/* *** FIX THIS: it would be better to desaturate than blindly clip. */
red = CLAMP (red, 0, 255);
green = CLAMP (green, 0, 255);
blue = CLAMP (blue, 0, 255);
/* Stuff result back into buffer */
b[0] = (guchar) red;
b[1] = (guchar) green;
b[2] = (guchar) blue;
/* *** FIXME: it would be better to desaturate than blindly clip. */
b[0] = (guchar) CLAMP (red, 0, 255);
b[1] = (guchar) CLAMP (green, 0, 255);
b[2] = (guchar) CLAMP (blue, 0, 255);
/* Put the result into our cache */
colorblind->cache[2 * index] = pixel;
@ -512,12 +513,9 @@ cdisplay_colorblind_changed (GimpColorDisplay *display)
* our anchors) (we can just peel this out of the rgb2lms transform
* matrix)
*/
anchor_e[0] =
colorblind->rgb2lms[0] + colorblind->rgb2lms[1] + colorblind->rgb2lms[2];
anchor_e[1] =
colorblind->rgb2lms[3] + colorblind->rgb2lms[4] + colorblind->rgb2lms[5];
anchor_e[2] =
colorblind->rgb2lms[6] + colorblind->rgb2lms[7] + colorblind->rgb2lms[8];
anchor_e[0] = rgb2lms[0] + rgb2lms[1] + rgb2lms[2];
anchor_e[1] = rgb2lms[3] + rgb2lms[4] + rgb2lms[5];
anchor_e[2] = rgb2lms[6] + rgb2lms[7] + rgb2lms[8];
switch (colorblind->deficiency)
{