Subversion Repositories shark

Rev

Details | Last modification | View Log | RSS feed

Rev Author Line No. Line
2 pj 1
/*
2
 * fs2fast.c --
3
 *
4
 *      Procedures dealing with a fast version of Floyd-Steinberg
5
 *      dithering with 2 error values propagated.
6
 */
7
 
8
/*
9
 * Copyright (c) 1995 The Regents of the University of California.
10
 * All rights reserved.
11
 *
12
 * Permission to use, copy, modify, and distribute this software and its
13
 * documentation for any purpose, without fee, and without written agreement is
14
 * hereby granted, provided that the above copyright notice and the following
15
 * two paragraphs appear in all copies of this software.
16
 *
17
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
18
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
19
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
20
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
21
 *
22
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
23
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
24
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
25
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
26
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
27
 */
28
 
29
#include "video.h"
30
#include "proto.h"
31
#include "dither.h"
32
#ifdef __STDC__
33
#include <stdlib.h>
34
#else
35
#include <malloc.h>
36
#endif
37
 
38
 
39
/* Arrays containing error values for floyd-steinberg dithering. */
40
 
41
static int deltay[256];
42
static int deltau[256];
43
static int deltav[256];
44
static int deltay2[256];
45
static int deltau2[256];
46
static int deltav2[256];
47
 
48
/* Definitions governing number of bits used for luminance, cr, and cb. */
49
 
50
#define L_BITS 3
51
#define CR_BITS 2
52
#define CB_BITS 2
53
 
54
/* Masks for proper quantization of lum, cr, and cb values. */
55
 
56
#define L_MASK 0xe0
57
#define CR_MASK 0xc0
58
#define CB_MASK 0xc0
59
 
60
 
61
 
62
/*
63
 *--------------------------------------------------------------
64
 *
65
 * InitFS2FastDither --
66
 *
67
 *    Initializes structures and arrays neeeded for fast implementation
68
 *      of two error F-S dithering.
69
 *
70
 * Results:
71
 *    None.
72
 *
73
 * Side effects:
74
 *      None.
75
 *
76
 *--------------------------------------------------------------
77
 */
78
 
79
void InitFS2FastDither()
80
{
81
  int i;
82
  int lum_num, cr_num, cb_num;
83
 
84
  for (i=0; i<256; i++) {
85
    lum_num = (i >> (8-L_BITS));
86
    cr_num = (i >> (8-CR_BITS));
87
    cb_num = (i >> (8-CB_BITS));
88
 
89
    /* These arrays contain the error values propogated for each pixel value
90
       for each channel.
91
    */
92
 
93
    deltay[i] = (i - ((int) lum_values[lum_num])) / 2;
94
    deltau[i] = (i-((int) cr_values[cr_num])) / 2;
95
    deltav[i] = (i-((int) cb_values[cb_num])) / 2;
96
    deltay2[i] = (i - ((int) lum_values[lum_num])) - deltay[i];
97
    deltau2[i] = (i - ((int) cr_values[cr_num])) - deltau[i];
98
    deltav2[i] = (i - ((int) cb_values[cb_num])) - deltav[i];
99
 
100
  }
101
 
102
}
103
 
104
 
105
/*
106
 *--------------------------------------------------------------
107
 *
108
 * DitherImage --
109
 *
110
 *    Dithers an image using floyd-steinberg.
111
 *    Assumptions made:
112
 *      1) The color space is allocated y:cr:cb = 8:4:4
113
 *      2) The spatial resolution of y:cr:cb is 4:1:1
114
 *
115
 * Results:
116
 *    None.
117
 *
118
 * Side effects:
119
 *    None.
120
 *
121
 *--------------------------------------------------------------
122
 */
123
void
124
FS2FastDitherImage (lum, cr, cb, out, h, w)
125
     unsigned char *lum;
126
     unsigned char *cr;
127
     unsigned char *cb;
128
     unsigned char *out;
129
     int w, h;
130
{
131
  int i, j, idx, idx2;
132
  int y, u, v;
133
  int dy, du, dv;
134
  int code;
135
  static int *yerr1;
136
  static int *yerr2;
137
  static int *uerr1;
138
  static int *uerr2;
139
  static int *verr1;
140
  static int *verr2;
141
  int *ye1, *ue1, *ve1;
142
  int *ye2, *ue2, *ve2;
143
  unsigned char *o, *l, *r, *b;
144
  static int first = 1;
145
 
146
  /* If first time called, allocate error arrays. */
147
 
148
  if (first) {
149
    first = 0;
150
    yerr1 = (int *) malloc((w+5)*sizeof(int));
151
    yerr2 = (int *) malloc((w+5)*sizeof(int));
152
    uerr1 = (int *) malloc((w+5)*sizeof(int));
153
    uerr2 = (int *) malloc((w+5)*sizeof(int));
154
    verr1 = (int *) malloc((w+5)*sizeof(int));
155
    verr2 = (int *) malloc((w+5)*sizeof(int));
156
  }
157
 
158
  /*
159
   * Init error arrays and variables.
160
   */
161
  memset ((char *)yerr1, 0, (w+5)*sizeof(int));
162
  memset ((char *)yerr2, 0, (w+5)*sizeof(int));
163
  memset ((char *)uerr1, 0, (w+5)*sizeof(int));
164
  memset ((char *)uerr2, 0, (w+5)*sizeof(int));
165
  memset ((char *)verr1, 0, (w+5)*sizeof(int));
166
  memset ((char *)verr2, 0, (w+5)*sizeof(int));
167
  du = dv = dy = 0;
168
 
169
  for (j=0; j<h; j+=2) {
170
    ye1 = yerr1;
171
    ue1 = uerr1;
172
    ve1 = verr1;
173
    ye2 = yerr2;
174
    ue2 = uerr2;
175
    ve2 = verr2;
176
    idx = j*w;
177
    idx2 = idx/4;
178
    o = out+idx;
179
    l = lum+idx;
180
    r = cr+idx2;
181
    b = cb+idx2;
182
 
183
    /* Do the top row in forward order. */
184
    for (i=0; i<w; i+=2) {
185
      /* Do left side of this pair... */
186
      y = *l++ + dy + *ye1++;
187
      u = *r + du + *ue1++;
188
      v = *b + dv + *ve1++;
189
 
190
      if (y < 0) {
191
        y = 0;
192
      } else if (y > 255) {
193
        y = 255;
194
      }
195
 
196
      if (u < 0) {
197
        u = 0;
198
      } else if (u > 255) {
199
        u = 255;
200
      }
201
 
202
      if (v < 0) {
203
        v = 0;
204
      } else if (v > 255) {
205
        v = 255;
206
      }
207
 
208
      /*
209
       * Construct a code using:
210
       *    high order 3 bits of y,
211
       *    high order 2 bits of u,
212
       *    high order 2 bits of v
213
       */
214
      code = (((y & L_MASK) | ((u & CR_MASK) >> L_BITS) | (v >> (L_BITS+CR_BITS)))
215
          >> (8-(L_BITS+CR_BITS+CB_BITS)));
216
      *o++ = pixel[code];
217
      *ye2++ = deltay[y];
218
      *ue2++ = deltau[u];
219
      *ve2++ = deltav[v];
220
      dy = deltay2[y];
221
      du = deltau2[u];
222
      dv = deltav2[v];
223
 
224
      /* Do right side of this pair... */
225
      y = *l++ + dy + *ye1++;
226
      u = *r++ + du + *ue1++;
227
      v = *b++ + dv + *ve1++;
228
 
229
      if (y < 0) {
230
        y = 0;
231
      } else if (y > 255) {
232
        y = 255;
233
      }
234
 
235
      if (u < 0) {
236
        u = 0;
237
      } else if (u > 255) {
238
        u = 255;
239
      }
240
 
241
      if (v < 0) {
242
        v = 0;
243
      } else if (v > 255) {
244
        v = 255;
245
      }
246
 
247
      code = (((y & L_MASK) | ((u & CR_MASK) >> L_BITS) | (v >> (L_BITS+CR_BITS)))
248
          >> (8-(L_BITS+CR_BITS+CB_BITS)));
249
      *o++ = pixel[code];
250
      *ye2++ = deltay[y];
251
      *ue2++ = deltau[u];
252
      *ve2++ = deltav[v];
253
      dy = deltay2[y];
254
      du = deltau2[u];
255
      dv = deltav2[v];
256
 
257
    }
258
 
259
    ye1 = yerr1+w-1;
260
    ue1 = uerr1+w-1;
261
    ve1 = verr1+w-1;
262
    ye2 = yerr2+w-1;
263
    ue2 = uerr2+w-1;
264
    ve2 = verr2+w-1;
265
    l += w-1;
266
    o += w-1;
267
    r--;
268
    b--;
269
    dy = du = dv = 0;
270
 
271
    /* Do bottom part of row, in right to left order. */
272
    for (i=w-1; i>0; i-=2) {
273
      /* Do right side of this pair... */
274
      y = *l-- + dy + *ye2--;
275
      u = *r + du + *ue2--;
276
      v = *b + dv + *ve2--;
277
 
278
      if (y < 0) {
279
        y = 0;
280
      } else if (y > 255) {
281
        y = 255;
282
      }
283
 
284
      if (u < 0) {
285
        u = 0;
286
      } else if (u > 255) {
287
        u = 255;
288
      }
289
 
290
      if (v < 0) {
291
        v = 0;
292
      } else if (v > 255) {
293
        v = 255;
294
      }
295
 
296
      /*
297
       * Construct a code using:
298
       *    high order 3 bits of y,
299
       *    high order 2 bits of u,
300
       *    high order 2 bits of v
301
       */
302
      code = (((y & L_MASK) | ((u & CR_MASK) >> L_BITS) | (v >> (L_BITS+CR_BITS)))
303
          >> (8-(L_BITS+CR_BITS+CB_BITS)));
304
      *o-- = pixel[code];
305
      *ye1-- = deltay[y];
306
      *ue1-- = deltau[u];
307
      *ve1-- = deltav[v];
308
      dy = deltay2[y];
309
      du = deltau2[u];
310
      dv = deltav2[v];
311
 
312
      /* Do left side of this pair... */
313
      y = *l-- + dy + *ye2--;
314
      u = *r-- + du + *ue2--;
315
      v = *b-- + dv + *ve2--;
316
 
317
      if (y < 0) {
318
        y = 0;
319
      } else if (y > 255) {
320
        y = 255;
321
      }
322
 
323
      if (u < 0) {
324
        u = 0;
325
      } else if (u > 255) {
326
        u = 255;
327
      }
328
 
329
      if (v < 0) {
330
        v = 0;
331
      } else if (v > 255) {
332
        v = 255;
333
      }
334
 
335
 
336
      code = (((y & L_MASK) | ((u & CR_MASK) >> L_BITS) | (v >> (L_BITS+CR_BITS)))
337
          >> (8-(L_BITS+CR_BITS+CB_BITS)));
338
      *o-- = pixel[code];
339
      *ye1-- = deltay[y];
340
      *ue1-- = deltau[u];
341
      *ve1-- = deltav[v];
342
      dy = deltay2[y];
343
      du = deltau2[u];
344
      dv = deltav2[v];
345
 
346
    }
347
  }
348
}
349
 
350
 
351
 
352
 
353