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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).
This commit is contained in:
Sven Neumann 2004-12-13 00:30:15 +00:00 committed by Sven Neumann
parent 6bb153b31c
commit 677fc5cc7e
2 changed files with 43 additions and 13 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
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> 2004-12-13 Sven Neumann <sven@gimp.org>
* app/gui/splash.c: restrict splash image to screen size to guard us * app/gui/splash.c: restrict splash image to screen size to guard us

51
app/core/gimpimage-convert.c
View File

@ -158,6 +158,10 @@
#include "gimp-intl.h" #include "gimp-intl.h"
#ifndef DM_RANGE
# define DM_RANGE 63
#endif
/* basic memory/quality tradeoff */ /* basic memory/quality tradeoff */
#define PRECISION_R 8 #define PRECISION_R 8
#define PRECISION_G 6 #define PRECISION_G 6
@ -2973,14 +2977,13 @@ median_cut_pass2_fixed_dither_gray (QuantizeObj *quantobj,
PixelRegion srcPR, destPR; PixelRegion srcPR, destPR;
CFHistogram histogram = quantobj->histogram; CFHistogram histogram = quantobj->histogram;
ColorFreq *cachep; ColorFreq *cachep;
int pixval1=0, pixval2=0; gint pixval1=0, pixval2=0;
int err1,err2; gint err1,err2;
Color* color1; Color* color1;
Color* color2; Color* color2;
guchar *src, *dest; guchar *src, *dest;
gint row, col; gint row, col;
gint pixel; gint pixel;
gint R;
gulong *index_used_count = quantobj->index_used_count; gulong *index_used_count = quantobj->index_used_count;
gboolean has_alpha; gboolean has_alpha;
gboolean alpha_dither = quantobj->want_alpha_dither; gboolean alpha_dither = quantobj->want_alpha_dither;
@ -3029,10 +3032,10 @@ median_cut_pass2_fixed_dither_gray (QuantizeObj *quantobj,
color1 = &quantobj->cmap[pixval1]; color1 = &quantobj->cmap[pixval1];
if (quantobj->actual_number_of_colors > 2) { 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; int RV = src[GRAY_PIX] + re;
do { do {
R = CLAMP0255(RV); const gint R = CLAMP0255(RV);
cachep = &histogram[R]; cachep = &histogram[R];
/* If we have not seen this color before, find nearest /* If we have not seen this color before, find nearest
colormap entry and update the cache */ colormap entry and update the cache */
@ -3042,7 +3045,7 @@ median_cut_pass2_fixed_dither_gray (QuantizeObj *quantobj,
pixval2 = *cachep - 1; pixval2 = *cachep - 1;
RV += re; RV += re;
} while((pixval1 == pixval2) && } while((pixval1 == pixval2) &&
(!( (RV>255 || RV<0) )) && (! (RV>255 || RV<0) ) &&
re); re);
} else { } else {
/* not enough colours to bother looking for an 'alternative' /* not enough colours to bother looking for an 'alternative'
@ -3051,13 +3054,24 @@ median_cut_pass2_fixed_dither_gray (QuantizeObj *quantobj,
pixval2 = (pixval1 + 1) % pixval2 = (pixval1 + 1) %
(quantobj->actual_number_of_colors); (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]; color2 = &quantobj->cmap[pixval2];
err1 = ABS(color1->red - src[GRAY_PIX]); err1 = ABS(color1->red - src[GRAY_PIX]);
err2 = ABS(color2->red - src[GRAY_PIX]); err2 = ABS(color2->red - src[GRAY_PIX]);
if (err1 || err2) { if (err1 || err2) {
const int proportion2 = (16 * 63 * err2) / (err1 + err2); const int proportion2 = (256* DM_RANGE * err2) / (err1 + err2);
if ((dmval * 16) > proportion2) { if ((dmval * 256) > proportion2) {
pixval1 = pixval2; /* use color2 instead of color1*/ pixval1 = pixval2; /* use color2 instead of color1*/
} }
} }
@ -3195,12 +3209,12 @@ median_cut_pass2_fixed_dither_rgb (QuantizeObj *quantobj,
PixelRegion srcPR, destPR; PixelRegion srcPR, destPR;
CFHistogram histogram = quantobj->histogram; CFHistogram histogram = quantobj->histogram;
ColorFreq *cachep; ColorFreq *cachep;
int pixval1=0, pixval2=0; gint pixval1=0, pixval2=0;
Color* color1; Color* color1;
Color* color2; Color* color2;
guchar *src, *dest; guchar *src, *dest;
gint R, G, B; gint R, G, B;
int err1,err2; gint err1,err2;
gint row, col; gint row, col;
gboolean has_alpha; gboolean has_alpha;
gpointer pr; 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) )) && (!( (RV>255 || RV<0) || (GV>255 || GV<0) || (BV>255 || BV<0) )) &&
(re || ge || be)); (re || ge || be));
} }
if (quantobj->actual_number_of_colors <= 2 /*|| if (quantobj->actual_number_of_colors <= 2
pixval1 == pixval2*/) { /* || pixval1 == pixval2 */) {
/* not enough colours to bother looking for an 'alternative' /* not enough colours to bother looking for an 'alternative'
colour (we may fail to do so anyway), so decide that colour (we may fail to do so anyway), so decide that
the alternative colour is simply the other cmap entry. */ the alternative colour is simply the other cmap entry. */
pixval2 = (pixval1 + 1) % pixval2 = (pixval1 + 1) %
(quantobj->actual_number_of_colors); (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]; color2 = &quantobj->cmap[pixval2];
/* now figure out the relative probabilites of choosing /* 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], src[red_pix], src[green_pix], src[blue_pix],
err2); err2);
if (err1 || err2) { if (err1 || err2) {
const int proportion2 = (63 * err2) / (err1 + err2); const int proportion2 = (DM_RANGE * err2) / (err1 + err2);
if (dmval > proportion2) { if (dmval > proportion2) {
pixval1 = pixval2; /* use color2 instead of color1*/ pixval1 = pixval2; /* use color2 instead of color1*/
} }