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/*
2
 * hybriderr.c --
3
 *
4
 *      Procedures dealing with hybrid2 dithering, which is hybrid
5
 *      dithering with error propagation among pixels.
6
 *
7
 */
8
 
9
/*
10
 * Copyright (c) 1995 The Regents of the University of California.
11
 * All rights reserved.
12
 *
13
 * Permission to use, copy, modify, and distribute this software and its
14
 * documentation for any purpose, without fee, and without written agreement is
15
 * hereby granted, provided that the above copyright notice and the following
16
 * two paragraphs appear in all copies of this software.
17
 *
18
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
19
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
20
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
21
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
22
 *
23
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
24
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
25
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
26
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
27
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
28
 */
29
 
30
/* This file contains C code to implement an ordered dither in the
31
   luminance channel and F-S error diffusion on chrominance.
32
*/
33
 
34
#include "video.h"
35
#include "proto.h"
36
#include "dither.h"
37
 
38
#define DITH_SIZE 16
39
 
40
/* Structures used for hybrid dither with errors propogated. */
41
 
42
static unsigned char *l_darrays[DITH_SIZE];
43
static unsigned char *l_darrays0, *l_darrays1, *l_darrays2, *l_darrays3;
44
static unsigned char *l_darrays4, *l_darrays5, *l_darrays6, *l_darrays7;
45
static unsigned char *l_darrays8, *l_darrays9, *l_darrays10, *l_darrays11;
46
static unsigned char *l_darrays12, *l_darrays13, *l_darrays14, *l_darrays15;
47
static unsigned char cr_fsarray[256*256][4];
48
static unsigned char cb_fsarray[256*256][4];
49
static unsigned short  c_fserr[256*256][2];
50
 
51
 
52
/*
53
 *--------------------------------------------------------------
54
 *
55
 *  InitHybridErrorDither--
56
 *
57
 *      Initializes structures used for hybrid dither algorithm
58
 *      with errors propogated on Cr and Cb.
59
 *
60
 * Results:
61
 *      None.
62
 *
63
 * Side effects:
64
 *      None.
65
 *
66
 *--------------------------------------------------------------
67
 */
68
 
69
void
70
InitHybridErrorDither()
71
{
72
  int i, j, k, err_range, threshval;
73
  unsigned char *lmark;
74
 
75
 
76
  for (i=0; i<DITH_SIZE; i++) {
77
    lmark = l_darrays[i] = (unsigned char *) malloc(256);
78
 
79
    for (j=0; j<lum_values[0]; j++) {
80
      *lmark++ = 0;
81
    }
82
 
83
    for (j=0; j<(LUM_RANGE-1); j++) {
84
      err_range = lum_values[j+1] - lum_values[j];
85
      threshval = ((i * err_range) / DITH_SIZE)+lum_values[j];
86
 
87
      for (k=lum_values[j]; k<lum_values[j+1]; k++) {
88
        if (k > threshval) *lmark++ = ((j+1) * (CR_RANGE * CB_RANGE));
89
        else *lmark++ = (j * (CR_RANGE * CB_RANGE));
90
      }
91
    }
92
 
93
    for (j=lum_values[LUM_RANGE-1]; j <256; j++) {
94
      *lmark++ = (LUM_RANGE-1)*(CR_RANGE * CB_RANGE);
95
    }
96
  }
97
  l_darrays0 = l_darrays[0]; l_darrays8 = l_darrays[8];
98
  l_darrays1 = l_darrays[1]; l_darrays9 = l_darrays[9];
99
  l_darrays2 = l_darrays[2]; l_darrays10 = l_darrays[10];
100
  l_darrays3 = l_darrays[3]; l_darrays11 = l_darrays[11];
101
  l_darrays4 = l_darrays[4]; l_darrays12 = l_darrays[12];
102
  l_darrays5 = l_darrays[5]; l_darrays13 = l_darrays[13];
103
  l_darrays6 = l_darrays[6]; l_darrays14 = l_darrays[14];
104
  l_darrays7 = l_darrays[7]; l_darrays15 = l_darrays[15];
105
  {
106
    int cr1, cr2, cr3, cr4, err1, err2;
107
    int cb1, cb2, cb3, cb4, val, nval;
108
    int outerr1, outerr2, outerr3, outerr4;
109
    int inerr1, inerr2, inerr3, inerr4;
110
    unsigned short oe1, oe2, oe3, oe4;
111
 
112
    for (j=0; j<65536; j+= 256) {
113
 
114
      inerr1 = (((j & 0xc000) >> 14)*8) - 12;
115
      inerr2 = (((j & 0x3000) >> 12)*8) - 12;
116
      inerr3 = (((j & 0x0c00) >> 10)*8) - 12;
117
      inerr4 = (((j & 0x0300) >> 8) *8) - 12;
118
 
119
      for (i=0; i<256; i++) {
120
        val = i;
121
 
122
        nval = val+inerr1+inerr3;
123
        if (nval < 0) nval = 0; else if (nval > 255) nval = 255;
124
        cr1 = ((nval) * CR_RANGE) / 256;
125
        err1 = ((nval) - cr_values[cr1])/2;
126
        err2 = ((nval) - cr_values[cr1]) - err1;
127
 
128
        nval = val+err1+inerr2;
129
        if (nval < 0) nval = 0; else if (nval > 255) nval = 255;
130
        cr2 = ((nval) * CR_RANGE) / 256;
131
        err1 = ((nval) - cr_values[cr2])/2;
132
        outerr3 = ((nval) - cr_values[cr2])-err1;
133
 
134
        nval = val+err2+inerr4;
135
        if (nval < 0) nval = 0; else if (nval > 255) nval = 255;
136
        cr3 = ((nval) * CR_RANGE) / 256;
137
        err2 = ((nval) - cr_values[cr3])/2;
138
        outerr1 = ((nval) - cr_values[cr3]) - err2;
139
 
140
        nval = val+err1+err2;
141
        if (nval < 0) nval = 0; else if (nval > 255) nval = 255;
142
        cr4 = ((nval) * CR_RANGE) / 256;
143
        outerr2 = ((nval) - cr_values[cr4])/2;
144
        outerr4 = ((nval) - cr_values[cr4])-outerr2;
145
 
146
        cr_fsarray[i+j][0] = cr1*CB_RANGE;
147
        cr_fsarray[i+j][1] = cr2*CB_RANGE;
148
        cr_fsarray[i+j][2] = cr3*CB_RANGE;
149
        cr_fsarray[i+j][3] = cr4*CB_RANGE;
150
 
151
        if (outerr1 < -16) outerr1++;
152
        else if (outerr1 > 15) outerr1--;
153
        if (outerr2 < -16) outerr2++;
154
        else if (outerr2 > 15) outerr2--;
155
        if (outerr3 < -16) outerr3++;
156
        else if (outerr3 > 15) outerr3--;
157
        if (outerr4 < -16) outerr4++;
158
        else if (outerr4 > 15) outerr4--;
159
 
160
        oe1 = (outerr1 + 16) / 8;
161
        oe2 = (outerr2 + 16) / 8;
162
        oe3 = (outerr3 + 16) / 8;
163
        oe4 = (outerr4 + 16) / 8;
164
 
165
/* This is a debugging check and should be removed if not needed. */
166
        if ((oe1 > 3) || (oe2 > 3) || (oe3 > 3) || (oe4 > 3))
167
          fprintf(stderr, "OE error!!!!\n");
168
 
169
 
170
        c_fserr[i+j][0] = ((oe1 << 14) | (oe2 << 12));
171
 
172
        c_fserr[i+j][1] = ((oe3 << 10) | (oe4 << 8));
173
      }
174
 
175
      for (i=0; i<256; i++) {
176
        val = i;
177
        nval = val+inerr1+inerr3;
178
        if (nval < 0) nval = 0; else if (nval > 255) nval = 255;    
179
        cb1 = ((nval) * CB_RANGE) / 256;
180
        err1 = ((nval) - cb_values[cb1])/2;
181
        err2 = ((nval) - cb_values[cb1]) - err1;
182
 
183
        nval = val+err1+inerr2;
184
        if (nval < 0) nval = 0; else if (nval > 255) nval = 255;    
185
        cb2 = ((nval) * CB_RANGE) / 256;
186
        err1 = ((nval) - cb_values[cb2])/2;
187
 
188
        nval = val+err2+inerr4;
189
        if (nval < 0) nval = 0; else if (nval > 255) nval = 255;    
190
        cb3 = ((nval) * CB_RANGE) / 256;
191
        err2 = ((nval) - cb_values[cb3])/2;
192
 
193
        nval = val+err1+err2;
194
        if (nval < 0) nval = 0; else if (nval > 255) nval = 255;    
195
        cb4 = ((nval) * CB_RANGE) / 256;
196
 
197
        cb_fsarray[i+j][0] = cb1;
198
        cb_fsarray[i+j][1] = cb2;
199
        cb_fsarray[i+j][2] = cb3;
200
        cb_fsarray[i+j][3] = cb4;
201
      }
202
    }
203
  }
204
}
205
 
206
 
207
/*
208
 *--------------------------------------------------------------
209
 *
210
 * HybridErrorDitherImage --
211
 *
212
 *      Dithers an image using a hybrid ordered/floyd-steinberg dither.
213
 *      Assumptions made:
214
 *        1) The color space is allocated y:cr:cb = 8:4:4
215
 *        2) The spatial resolution of y:cr:cb is 4:1:1
216
 *      This dither is almost exactly like the dither implemented in the
217
 *      file odith.c (i.e. hybrid dithering) except a quantized amount of
218
 *      error is propogated between 2x2 pixel areas in Cr and Cb.
219
 *
220
 * Results:
221
 *      None.
222
 *
223
 * Side effects:
224
 *      None.
225
 *
226
 *--------------------------------------------------------------
227
 */
228
void
229
HybridErrorDitherImage (lum, cr, cb, out, h, w)
230
    unsigned char *lum;
231
    unsigned char *cr;
232
    unsigned char *cb;
233
    unsigned char *out;
234
    int w, h;
235
{
236
  unsigned char *l, *r, *b, *o1, *o2;
237
  unsigned char *l2;
238
  static int *cr_row_errs;
239
  static int *cb_row_errs;
240
  int *cr_r_err;
241
  int *cb_r_err;
242
  int cr_c_err;
243
  int cb_c_err;
244
  unsigned char *cr_fsptr;
245
  unsigned char *cb_fsptr;
246
  static int first = 1;
247
  int cr_code, cb_code;
248
 
249
  int i, j;
250
  int row_advance, row_advance2;
251
  int half_row_advance, half_row_advance2;
252
 
253
  /* If first time called, allocate error arrays. */
254
 
255
  if (first) {
256
    cr_row_errs = (int *) malloc((w+5)*sizeof(int));
257
    cb_row_errs = (int *) malloc((w+5)*sizeof(int));
258
    first = 0;
259
  }
260
 
261
  row_advance = (w << 1) - 1;
262
  row_advance2 = row_advance+2;
263
  half_row_advance = (w>>1)-1;
264
  half_row_advance2 = half_row_advance+2;
265
 
266
  l = lum;
267
  l2 = lum+w;
268
  r = cr;
269
  b = cb;
270
  o1 = out;
271
  o2 = out+w;
272
 
273
  memset( (char *) cr_row_errs, 0, (w+5)*sizeof(int));
274
  cr_r_err = cr_row_errs;
275
  cr_c_err = 0;
276
  memset( (char *) cb_row_errs, 0, (w+5)*sizeof(int));
277
  cb_r_err = cb_row_errs;
278
  cb_c_err = 0;
279
 
280
  for (i=0; i<h; i+=4) {
281
 
282
    for (j=w; j>0; j-=4) {
283
 
284
      cr_code = (*cr_r_err | cr_c_err | *r++);
285
      cb_code = (*cb_r_err | cb_c_err | *b++);
286
 
287
      cr_fsptr = cr_fsarray[cr_code];
288
      cb_fsptr = cb_fsarray[cb_code];
289
 
290
      *o1++ = pixel[(l_darrays0[*l++] | *cr_fsptr++ | *cb_fsptr++)];
291
      *o1++ = pixel[(l_darrays8[*l++] | *cr_fsptr++ | *cb_fsptr++)];
292
      *o2++ = pixel[(l_darrays12[*l2++] | *cr_fsptr++ | *cb_fsptr++)];
293
      *o2++ = pixel[(l_darrays4[*l2++] | *cr_fsptr++ | *cb_fsptr++)];
294
 
295
      cr_c_err = c_fserr[cr_code][1];
296
      cb_c_err = c_fserr[cb_code][1];
297
      *cr_r_err++ = c_fserr[cr_code][0];
298
      *cb_r_err++ = c_fserr[cb_code][0];
299
      cr_code = (*cr_r_err | cr_c_err | *r++);
300
      cb_code = (*cb_r_err | cb_c_err | *b++);
301
 
302
      cr_fsptr = cr_fsarray[cr_code];
303
      cb_fsptr = cb_fsarray[cb_code];
304
 
305
      *o1++ = pixel[(l_darrays2[*l++] | *cr_fsptr++ | *cb_fsptr++)];
306
      *o1++ = pixel[(l_darrays10[*l++] | *cr_fsptr++ | *cb_fsptr++)];
307
      *o2++ = pixel[(l_darrays14[*l2++] | *cr_fsptr++ | *cb_fsptr++)];
308
      *o2++ = pixel[(l_darrays6[*l2++] | *cr_fsptr++ | *cb_fsptr++)];
309
 
310
      cr_c_err = c_fserr[cr_code][1];
311
      cb_c_err = c_fserr[cb_code][1];
312
      *cr_r_err++ = c_fserr[cr_code][0];
313
      *cb_r_err++ = c_fserr[cb_code][0];
314
    }
315
 
316
    l += row_advance; l2 += row_advance;
317
    o1 += row_advance; o2 += row_advance;
318
    cr_c_err = 0;
319
    cb_c_err = 0;
320
    cr_r_err--; cb_r_err--;
321
    r += half_row_advance; b += half_row_advance;
322
 
323
    for (j=w; j>0; j-=4) {
324
 
325
      cr_code = (*cr_r_err | cr_c_err | *r--);
326
      cb_code = (*cb_r_err | cb_c_err | *b--);
327
      cr_fsptr = cr_fsarray[cr_code];
328
      cb_fsptr = cb_fsarray[cb_code];
329
 
330
      *o1-- = pixel[(l_darrays9[*l--] | *cr_fsptr++ | *cb_fsptr++)];
331
      *o1-- = pixel[(l_darrays1[*l--] | *cr_fsptr++ | *cb_fsptr++)];
332
      *o2-- = pixel[(l_darrays5[*l2--] | *cr_fsptr++ | *cb_fsptr++)];
333
      *o2-- = pixel[(l_darrays13[*l2--] | *cr_fsptr++ | *cb_fsptr++)];
334
 
335
      cr_c_err = c_fserr[cr_code][1];
336
      cb_c_err = c_fserr[cb_code][1];
337
      *cr_r_err-- = c_fserr[cr_code][0];
338
      *cb_r_err-- = c_fserr[cb_code][0];
339
      cr_code = (*cr_r_err | cr_c_err | *r--);
340
      cb_code = (*cb_r_err | cb_c_err | *b--);
341
      cr_fsptr = cr_fsarray[cr_code];
342
      cb_fsptr = cb_fsarray[cb_code];
343
 
344
      *o1-- = pixel[(l_darrays11[*l--] | *cr_fsptr++ | *cb_fsptr++)];
345
      *o1-- = pixel[(l_darrays3[*l--] | *cr_fsptr++ | *cb_fsptr++)];
346
      *o2-- = pixel[(l_darrays7[*l2--] | *cr_fsptr++ | *cb_fsptr++)];
347
      *o2-- = pixel[(l_darrays15[*l2--] | *cr_fsptr++ | *cb_fsptr++)];
348
 
349
      cr_c_err = c_fserr[cr_code][1];
350
      cb_c_err = c_fserr[cb_code][1];
351
      *cr_r_err-- = c_fserr[cr_code][0];
352
      *cb_r_err-- = c_fserr[cb_code][0];
353
 
354
    }
355
 
356
    l += row_advance2; l2 += row_advance2;
357
    o1 += row_advance2; o2 += row_advance2;
358
    cr_c_err = 0; cb_c_err = 0;
359
    cr_r_err++; cb_r_err++;
360
    r += half_row_advance2; b += half_row_advance2;
361
  }
362
}
363
 
364
 
365