Commit 677fc5cc authored by Sven Neumann's avatar Sven Neumann Committed by Sven Neumann

applied patch from Adam D. Moss with more fixed dither improvements (bug

2004-12-13  Sven Neumann  <sven@gimp.org>

	* app/core/gimpimage-convert.c: applied patch from Adam D. Moss with
	more fixed dither improvements (bug #161123).
parent 6bb153b3
2004-12-13 Sven Neumann <sven@gimp.org>
* app/core/gimpimage-convert.c: applied patch from Adam D. Moss with
more fixed dither improvements (bug #161123).
2004-12-13 Sven Neumann <sven@gimp.org>
* app/gui/splash.c: restrict splash image to screen size to guard us
......
......@@ -158,6 +158,10 @@
#include "gimp-intl.h"
#ifndef DM_RANGE
# define DM_RANGE 63
#endif
/* basic memory/quality tradeoff */
#define PRECISION_R 8
#define PRECISION_G 6
......@@ -2973,14 +2977,13 @@ median_cut_pass2_fixed_dither_gray (QuantizeObj *quantobj,
PixelRegion srcPR, destPR;
CFHistogram histogram = quantobj->histogram;
ColorFreq *cachep;
int pixval1=0, pixval2=0;
int err1,err2;
gint pixval1=0, pixval2=0;
gint err1,err2;
Color* color1;
Color* color2;
guchar *src, *dest;
gint row, col;
gint pixel;
gint R;
gulong *index_used_count = quantobj->index_used_count;
gboolean has_alpha;
gboolean alpha_dither = quantobj->want_alpha_dither;
......@@ -3029,10 +3032,10 @@ median_cut_pass2_fixed_dither_gray (QuantizeObj *quantobj,
color1 = &quantobj->cmap[pixval1];
if (quantobj->actual_number_of_colors > 2) {
const int re = src[GRAY_PIX] - color1->red;
const int re = src[GRAY_PIX] - (int)color1->red;
int RV = src[GRAY_PIX] + re;
do {
R = CLAMP0255(RV);
const gint R = CLAMP0255(RV);
cachep = &histogram[R];
/* If we have not seen this color before, find nearest
colormap entry and update the cache */
......@@ -3042,7 +3045,7 @@ median_cut_pass2_fixed_dither_gray (QuantizeObj *quantobj,
pixval2 = *cachep - 1;
RV += re;
} while((pixval1 == pixval2) &&
(!( (RV>255 || RV<0) )) &&
(! (RV>255 || RV<0) ) &&
re);
} else {
/* not enough colours to bother looking for an 'alternative'
......@@ -3051,13 +3054,24 @@ median_cut_pass2_fixed_dither_gray (QuantizeObj *quantobj,
pixval2 = (pixval1 + 1) %
(quantobj->actual_number_of_colors);
}
/* always deterministically sort pixval1 and pixval2, to
avoid artifacts in the dither range due to inverting our
relative colour viewpoint -- most obvious in 1-bit dither. */
if (pixval1 > pixval2) {
gint tmpval = pixval1;
pixval1 = pixval2;
pixval2 = tmpval;
color1 = &quantobj->cmap[pixval1];
}
color2 = &quantobj->cmap[pixval2];
err1 = ABS(color1->red - src[GRAY_PIX]);
err2 = ABS(color2->red - src[GRAY_PIX]);
if (err1 || err2) {
const int proportion2 = (16 * 63 * err2) / (err1 + err2);
if ((dmval * 16) > proportion2) {
const int proportion2 = (256* DM_RANGE * err2) / (err1 + err2);
if ((dmval * 256) > proportion2) {
pixval1 = pixval2; /* use color2 instead of color1*/
}
}
......@@ -3195,12 +3209,12 @@ median_cut_pass2_fixed_dither_rgb (QuantizeObj *quantobj,
PixelRegion srcPR, destPR;
CFHistogram histogram = quantobj->histogram;
ColorFreq *cachep;
int pixval1=0, pixval2=0;
gint pixval1=0, pixval2=0;
Color* color1;
Color* color2;
guchar *src, *dest;
gint R, G, B;
int err1,err2;
gint err1,err2;
gint row, col;
gboolean has_alpha;
gpointer pr;
......@@ -3315,14 +3329,25 @@ median_cut_pass2_fixed_dither_rgb (QuantizeObj *quantobj,
(!( (RV>255 || RV<0) || (GV>255 || GV<0) || (BV>255 || BV<0) )) &&
(re || ge || be));
}
if (quantobj->actual_number_of_colors <= 2 /*||
pixval1 == pixval2*/) {
if (quantobj->actual_number_of_colors <= 2
/* || pixval1 == pixval2 */) {
/* not enough colours to bother looking for an 'alternative'
colour (we may fail to do so anyway), so decide that
the alternative colour is simply the other cmap entry. */
pixval2 = (pixval1 + 1) %
(quantobj->actual_number_of_colors);
}
/* always deterministically sort pixval1 and pixval2, to
avoid artifacts in the dither range due to inverting our
relative colour viewpoint -- most obvious in 1-bit dither. */
if (pixval1 > pixval2) {
gint tmpval = pixval1;
pixval1 = pixval2;
pixval2 = tmpval;
color1 = &quantobj->cmap[pixval1];
}
color2 = &quantobj->cmap[pixval2];
/* now figure out the relative probabilites of choosing
......@@ -3348,7 +3373,7 @@ median_cut_pass2_fixed_dither_rgb (QuantizeObj *quantobj,
src[red_pix], src[green_pix], src[blue_pix],
err2);
if (err1 || err2) {
const int proportion2 = (63 * err2) / (err1 + err2);
const int proportion2 = (DM_RANGE * err2) / (err1 + err2);
if (dmval > proportion2) {
pixval1 = pixval2; /* use color2 instead of color1*/
}
......
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