1 |
greg |
1.2 |
/* Copyright 1988 Regents of the University of California */ |
2 |
greg |
1.1 |
|
3 |
|
|
#ifndef lint |
4 |
|
|
static char SCCSid[] = "$SunId$ LBL"; |
5 |
|
|
#endif |
6 |
greg |
1.2 |
|
7 |
|
|
/* |
8 |
greg |
1.1 |
CIQ - main program for color image quantization |
9 |
|
|
options for Floyd-Steinberg dithering by minimization of accumulated error |
10 |
|
|
or undithered quantization |
11 |
|
|
|
12 |
|
|
Paul Heckbert 16 April 82, cleaned up 8 June 86 |
13 |
|
|
Greg Ward 1 March 88, modified for arbitrary picture sizes |
14 |
|
|
*/ |
15 |
|
|
|
16 |
|
|
#include "ciq.h" |
17 |
|
|
|
18 |
|
|
#define table(m,r,g,b) hist[m[0][r]|m[1][g]|m[2][b]] /* histogram/pvtable */ |
19 |
|
|
|
20 |
|
|
int hist[len]; /* list of frequencies or pixelvalues for coded color */ |
21 |
|
|
|
22 |
|
|
colormap color; /* quantization colormap */ |
23 |
|
|
int n; /* number of colors in it */ |
24 |
|
|
|
25 |
ph |
1.4 |
#define ERRMAX 20 /* maximum allowed propagated error, |
26 |
|
|
if >=255 then no clamping */ |
27 |
|
|
|
28 |
greg |
1.1 |
/*----------------------------------------------------------------------*/ |
29 |
|
|
|
30 |
|
|
ciq(dith,nw,synth,cm) |
31 |
|
|
int dith; /* is dithering desired? 0=no, 1=yes */ |
32 |
|
|
int nw; /* number of colors wanted in output image */ |
33 |
|
|
int synth; /* synthesize colormap? 0=no, 1=yes */ |
34 |
|
|
colormap cm; /* quantization colormap */ |
35 |
|
|
/* read if synth=0; always written */ |
36 |
|
|
{ |
37 |
|
|
int na,i; |
38 |
|
|
colormap ocm; |
39 |
|
|
|
40 |
|
|
picreadcm(ocm); /* read original picture's colormap (usually identity)*/ |
41 |
|
|
sample(ocm); /* find histogram */ |
42 |
|
|
|
43 |
|
|
if (synth) |
44 |
|
|
n = makecm(nw,&na); /* analyze histogram and synthesize colormap */ |
45 |
|
|
else { |
46 |
greg |
1.5 |
bcopy((char *)cm,(char *)color,sizeof color); |
47 |
greg |
1.1 |
n = nw; |
48 |
|
|
na = 0; |
49 |
|
|
for (i=0; i<len; i++) if (hist[i]) na++; |
50 |
|
|
/*printf("from %d to %d colors\n",na,n);*/ |
51 |
|
|
} |
52 |
|
|
picwritecm(color); |
53 |
|
|
|
54 |
ph |
1.4 |
initializeclosest(); |
55 |
greg |
1.1 |
if (dith) |
56 |
|
|
draw_dith(ocm); |
57 |
|
|
else { |
58 |
|
|
for (i=0; i<len; i++) |
59 |
|
|
if (hist[i]) hist[i] = closest(red(i),gre(i),blu(i)); |
60 |
|
|
draw_nodith(ocm); |
61 |
|
|
} |
62 |
|
|
|
63 |
greg |
1.5 |
bcopy((char *)color,(char *)cm,sizeof color); |
64 |
greg |
1.1 |
/*endclosest();*/ |
65 |
|
|
} |
66 |
|
|
|
67 |
|
|
/*----------------------------------------------------------------------*/ |
68 |
|
|
|
69 |
|
|
sample(ocm) /* make color frequency table (histogram) */ |
70 |
|
|
colormap ocm; |
71 |
|
|
{ |
72 |
|
|
register int x,y; |
73 |
|
|
register rgbpixel *lp; |
74 |
|
|
rgbpixel *line; |
75 |
|
|
colormap map; |
76 |
|
|
|
77 |
greg |
1.3 |
for (x = 0; x < len; x++) /* clear histogram */ |
78 |
|
|
hist[x] = 0; |
79 |
|
|
|
80 |
greg |
1.1 |
line = line3alloc(xmax); |
81 |
|
|
convertmap(ocm,map); |
82 |
|
|
|
83 |
|
|
for (y=0; y<ymax; y++) { |
84 |
|
|
picreadline3(y,line); |
85 |
|
|
for (lp=line, x=0; x<xmax; x++, lp++) |
86 |
|
|
table(map,lp->r,lp->g,lp->b)++; |
87 |
|
|
} |
88 |
|
|
free((char *)line); |
89 |
|
|
} |
90 |
|
|
|
91 |
|
|
convertmap(in,out) /* convert to shifted color map */ |
92 |
|
|
register colormap in,out; |
93 |
|
|
{ |
94 |
|
|
register int j; |
95 |
|
|
|
96 |
|
|
for (j=0; j<256; j++) { |
97 |
|
|
out[0][j] = (in[0][j]&0xf8)<<7; |
98 |
|
|
out[1][j] = (in[1][j]&0xf8)<<2; |
99 |
|
|
out[2][j] = (in[2][j]&0xf8)>>3; |
100 |
|
|
} |
101 |
|
|
} |
102 |
|
|
|
103 |
|
|
draw_nodith(ocm) /* quantize without dithering */ |
104 |
|
|
colormap ocm; /* colormap for orig */ |
105 |
|
|
{ |
106 |
|
|
register int x,y; |
107 |
|
|
register rgbpixel *lp; |
108 |
|
|
rgbpixel *iline; |
109 |
|
|
pixel *oline; |
110 |
|
|
colormap map; |
111 |
|
|
|
112 |
|
|
iline = line3alloc(xmax); |
113 |
|
|
oline = linealloc(xmax); |
114 |
|
|
convertmap(ocm,map); |
115 |
|
|
|
116 |
|
|
for (y=0; y<ymax; y++) { |
117 |
|
|
picreadline3(y,iline); |
118 |
|
|
for (lp=iline, x=0; x<xmax; x++, lp++) |
119 |
|
|
oline[x] = table(map,lp->r,lp->g,lp->b); |
120 |
|
|
picwriteline(y,oline); |
121 |
|
|
} |
122 |
|
|
free((char *)iline); |
123 |
|
|
free((char *)oline); |
124 |
|
|
} |
125 |
|
|
|
126 |
|
|
draw_dith(ocm) /* quantize with dithering */ |
127 |
|
|
colormap ocm; /* colormap for orig */ |
128 |
|
|
{ |
129 |
|
|
register int *p,*q,rr,gg,bb,v,x,y,*P,*Q,*R; |
130 |
|
|
int *buf; |
131 |
|
|
rgbpixel *iline; /* input scanline */ |
132 |
|
|
pixel *oline; /* output scanline */ |
133 |
|
|
|
134 |
|
|
buf = (int *)ecalloc(2,3*sizeof(int)*(xmax+1)); |
135 |
|
|
iline = line3alloc(xmax); |
136 |
|
|
oline = linealloc(xmax); |
137 |
|
|
/* reuse hist array as quantization table */ |
138 |
|
|
for (v=0; v<len; v++) hist[v] = -1; |
139 |
|
|
|
140 |
|
|
P = &buf[0]; |
141 |
|
|
Q = &buf[3*(xmax+1)]; |
142 |
|
|
for (y=0; y<ymax; y++, R=P, P=Q, Q=R) { |
143 |
|
|
Q[0] = Q[1] = Q[2] = 0; |
144 |
|
|
picreadline3(y,iline); |
145 |
|
|
for (p=P, q=Q, x=0; x<xmax; x++, p+=3, q+=3) { |
146 |
ph |
1.4 |
rr = p[0]; |
147 |
|
|
if (rr<-ERRMAX) rr = -ERRMAX; else if (rr>ERRMAX) rr = ERRMAX; |
148 |
|
|
gg = p[1]; |
149 |
|
|
if (gg<-ERRMAX) gg = -ERRMAX; else if (gg>ERRMAX) gg = ERRMAX; |
150 |
|
|
bb = p[2]; |
151 |
|
|
if (bb<-ERRMAX) bb = -ERRMAX; else if (bb>ERRMAX) bb = ERRMAX; |
152 |
|
|
/* now rr,gg,bb is propagated color */ |
153 |
|
|
rr += ocm[0][iline[x].r]; |
154 |
|
|
gg += ocm[1][iline[x].g]; /* ideal */ |
155 |
|
|
bb += ocm[2][iline[x].b]; |
156 |
greg |
1.1 |
if (rr<0) rr = 0; else if (rr>255) rr = 255; |
157 |
|
|
if (gg<0) gg = 0; else if (gg>255) gg = 255; |
158 |
|
|
if (bb<0) bb = 0; else if (bb>255) bb = 255; |
159 |
|
|
v = (rr&0xf8)<<7 | (gg&0xf8)<<2 | (bb&0xf8)>>3; |
160 |
|
|
if (hist[v]<0) |
161 |
|
|
hist[v] = closest(rr,gg,bb); /* nearest to ideal */ |
162 |
|
|
oline[x] = v = hist[v]; |
163 |
|
|
rr -= color[0][v]; |
164 |
|
|
gg -= color[1][v]; /* error */ |
165 |
|
|
bb -= color[2][v]; |
166 |
|
|
v = rr*3>>3; p[3] += v; q[0] += v; q[3] = rr-(v<<1); |
167 |
|
|
v = gg*3>>3; p[4] += v; q[1] += v; q[4] = gg-(v<<1); |
168 |
|
|
v = bb*3>>3; p[5] += v; q[2] += v; q[5] = bb-(v<<1); |
169 |
|
|
} |
170 |
|
|
picwriteline(y,oline); |
171 |
|
|
} |
172 |
|
|
free((char *)iline); |
173 |
|
|
free((char *)oline); |
174 |
|
|
free((char *)buf); |
175 |
|
|
} |