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jdmerge.c
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1 /*
2  * jdmerge.c
3  *
4  * Copyright (C) 1994-1995, Thomas G. Lane.
5  * This file is part of the Independent JPEG Group's software.
6  * For conditions of distribution and use, see the accompanying README file.
7  *
8  * This file contains code for merged upsampling/color conversion.
9  *
10  * This file combines functions from jdsample.c and jdcolor.c;
11  * read those files first to understand what's going on.
12  *
13  * When the chroma components are to be upsampled by simple replication
14  * (ie, box filtering), we can save some work in color conversion by
15  * calculating all the output pixels corresponding to a pair of chroma
16  * samples at one time. In the conversion equations
17  * R = Y + K1 * Cr
18  * G = Y + K2 * Cb + K3 * Cr
19  * B = Y + K4 * Cb
20  * only the Y term varies among the group of pixels corresponding to a pair
21  * of chroma samples, so the rest of the terms can be calculated just once.
22  * At typical sampling ratios, this eliminates half or three-quarters of the
23  * multiplications needed for color conversion.
24  *
25  * This file currently provides implementations for the following cases:
26  * YCbCr => RGB color conversion only.
27  * Sampling ratios of 2h1v or 2h2v.
28  * No scaling needed at upsample time.
29  * Corner-aligned (non-CCIR601) sampling alignment.
30  * Other special cases could be added, but in most applications these are
31  * the only common cases. (For uncommon cases we fall back on the more
32  * general code in jdsample.c and jdcolor.c.)
33  */
34 
35 #define JPEG_INTERNALS
36 #include "jinclude.h"
37 #include "jpeglib.h"
38 
39 #ifdef UPSAMPLE_MERGING_SUPPORTED
40 
41 
42 /* Private subobject */
43 
44 typedef struct {
45  struct jpeg_upsampler pub; /* public fields */
46 
47  /* Pointer to routine to do actual upsampling/conversion of one row group */
48  JMETHOD(void, upmethod, (j_decompress_ptr cinfo,
49  JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
50  JSAMPARRAY output_buf));
51 
52  /* Private state for YCC->RGB conversion */
53  int * Cr_r_tab; /* => table for Cr to R conversion */
54  int * Cb_b_tab; /* => table for Cb to B conversion */
55  INT32 * Cr_g_tab; /* => table for Cr to G conversion */
56  INT32 * Cb_g_tab; /* => table for Cb to G conversion */
57 
58  /* For 2:1 vertical sampling, we produce two output rows at a time.
59  * We need a "spare" row buffer to hold the second output row if the
60  * application provides just a one-row buffer; we also use the spare
61  * to discard the dummy last row if the image height is odd.
62  */
63  JSAMPROW spare_row;
64  boolean spare_full; /* T if spare buffer is occupied */
65 
66  JDIMENSION out_row_width; /* samples per output row */
67  JDIMENSION rows_to_go; /* counts rows remaining in image */
68 } my_upsampler;
69 
71 
72 #define SCALEBITS 16 /* speediest right-shift on some machines */
73 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
74 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
75 
76 
77 /*
78  * Initialize tables for YCC->RGB colorspace conversion.
79  * This is taken directly from jdcolor.c; see that file for more info.
80  */
81 
82 LOCAL void
84 {
85  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
86  int i;
87  INT32 x;
89 
90  upsample->Cr_r_tab = (int *)
91  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
92  (MAXJSAMPLE+1) * SIZEOF(int));
93  upsample->Cb_b_tab = (int *)
94  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
95  (MAXJSAMPLE+1) * SIZEOF(int));
96  upsample->Cr_g_tab = (INT32 *)
97  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
98  (MAXJSAMPLE+1) * SIZEOF(INT32));
99  upsample->Cb_g_tab = (INT32 *)
100  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
101  (MAXJSAMPLE+1) * SIZEOF(INT32));
102 
103  for (i = 0, x = -CENTERJSAMPLE; i <= MAXJSAMPLE; i++, x++) {
104  /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
105  /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
106  /* Cr=>R value is nearest int to 1.40200 * x */
107  upsample->Cr_r_tab[i] = (int)
108  RIGHT_SHIFT(FIX(1.40200) * x + ONE_HALF, SCALEBITS);
109  /* Cb=>B value is nearest int to 1.77200 * x */
110  upsample->Cb_b_tab[i] = (int)
111  RIGHT_SHIFT(FIX(1.77200) * x + ONE_HALF, SCALEBITS);
112  /* Cr=>G value is scaled-up -0.71414 * x */
113  upsample->Cr_g_tab[i] = (- FIX(0.71414)) * x;
114  /* Cb=>G value is scaled-up -0.34414 * x */
115  /* We also add in ONE_HALF so that need not do it in inner loop */
116  upsample->Cb_g_tab[i] = (- FIX(0.34414)) * x + ONE_HALF;
117  }
118 }
119 
120 
121 /*
122  * Initialize for an upsampling pass.
123  */
124 
125 METHODDEF void
126 start_pass_merged_upsample (j_decompress_ptr cinfo)
127 {
128  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
129 
130  /* Mark the spare buffer empty */
131  upsample->spare_full = FALSE;
132  /* Initialize total-height counter for detecting bottom of image */
133  upsample->rows_to_go = cinfo->output_height;
134 }
135 
136 
137 /*
138  * Control routine to do upsampling (and color conversion).
139  *
140  * The control routine just handles the row buffering considerations.
141  */
142 
143 METHODDEF void
144 merged_2v_upsample (j_decompress_ptr cinfo,
145  JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
146  JDIMENSION in_row_groups_avail,
147  JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
148  JDIMENSION out_rows_avail)
149 /* 2:1 vertical sampling case: may need a spare row. */
150 {
151  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
152  JSAMPROW work_ptrs[2];
153  JDIMENSION num_rows; /* number of rows returned to caller */
154 
155  if (upsample->spare_full) {
156  /* If we have a spare row saved from a previous cycle, just return it. */
157  jcopy_sample_rows(& upsample->spare_row, 0, output_buf + *out_row_ctr, 0,
158  1, upsample->out_row_width);
159  num_rows = 1;
160  upsample->spare_full = FALSE;
161  } else {
162  /* Figure number of rows to return to caller. */
163  num_rows = 2;
164  /* Not more than the distance to the end of the image. */
165  if (num_rows > upsample->rows_to_go)
166  num_rows = upsample->rows_to_go;
167  /* And not more than what the client can accept: */
168  out_rows_avail -= *out_row_ctr;
169  if (num_rows > out_rows_avail)
170  num_rows = out_rows_avail;
171  /* Create output pointer array for upsampler. */
172  work_ptrs[0] = output_buf[*out_row_ctr];
173  if (num_rows > 1) {
174  work_ptrs[1] = output_buf[*out_row_ctr + 1];
175  } else {
176  work_ptrs[1] = upsample->spare_row;
177  upsample->spare_full = TRUE;
178  }
179  /* Now do the upsampling. */
180  (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr, work_ptrs);
181  }
182 
183  /* Adjust counts */
184  *out_row_ctr += num_rows;
185  upsample->rows_to_go -= num_rows;
186  /* When the buffer is emptied, declare this input row group consumed */
187  if (! upsample->spare_full)
188  (*in_row_group_ctr)++;
189 }
190 
191 
192 METHODDEF void
193 merged_1v_upsample (j_decompress_ptr cinfo,
194  JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
195  JDIMENSION in_row_groups_avail,
196  JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
197  JDIMENSION out_rows_avail)
198 /* 1:1 vertical sampling case: much easier, never need a spare row. */
199 {
200  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
201 
202  /* Just do the upsampling. */
203  (*upsample->upmethod) (cinfo, input_buf, *in_row_group_ctr,
204  output_buf + *out_row_ctr);
205  /* Adjust counts */
206  (*out_row_ctr)++;
207  (*in_row_group_ctr)++;
208 }
209 
210 
211 /*
212  * These are the routines invoked by the control routines to do
213  * the actual upsampling/conversion. One row group is processed per call.
214  *
215  * Note: since we may be writing directly into application-supplied buffers,
216  * we have to be honest about the output width; we can't assume the buffer
217  * has been rounded up to an even width.
218  */
219 
220 
221 /*
222  * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.
223  */
224 
225 METHODDEF void
226 h2v1_merged_upsample (j_decompress_ptr cinfo,
227  JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
228  JSAMPARRAY output_buf)
229 {
230  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
231  register int y, cred, cgreen, cblue;
232  int cb, cr;
233  register JSAMPROW outptr;
234  JSAMPROW inptr0, inptr1, inptr2;
235  JDIMENSION col;
236  /* copy these pointers into registers if possible */
237  register JSAMPLE * range_limit = cinfo->sample_range_limit;
238  int * Crrtab = upsample->Cr_r_tab;
239  int * Cbbtab = upsample->Cb_b_tab;
240  INT32 * Crgtab = upsample->Cr_g_tab;
241  INT32 * Cbgtab = upsample->Cb_g_tab;
243 
244  inptr0 = input_buf[0][in_row_group_ctr];
245  inptr1 = input_buf[1][in_row_group_ctr];
246  inptr2 = input_buf[2][in_row_group_ctr];
247  outptr = output_buf[0];
248  /* Loop for each pair of output pixels */
249  for (col = cinfo->output_width >> 1; col > 0; col--) {
250  /* Do the chroma part of the calculation */
251  cb = GETJSAMPLE(*inptr1++);
252  cr = GETJSAMPLE(*inptr2++);
253  cred = Crrtab[cr];
254  cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
255  cblue = Cbbtab[cb];
256  /* Fetch 2 Y values and emit 2 pixels */
257  y = GETJSAMPLE(*inptr0++);
258  outptr[RGB_RED] = range_limit[y + cred];
259  outptr[RGB_GREEN] = range_limit[y + cgreen];
260  outptr[RGB_BLUE] = range_limit[y + cblue];
261  outptr += RGB_PIXELSIZE;
262  y = GETJSAMPLE(*inptr0++);
263  outptr[RGB_RED] = range_limit[y + cred];
264  outptr[RGB_GREEN] = range_limit[y + cgreen];
265  outptr[RGB_BLUE] = range_limit[y + cblue];
266  outptr += RGB_PIXELSIZE;
267  }
268  /* If image width is odd, do the last output column separately */
269  if (cinfo->output_width & 1) {
270  cb = GETJSAMPLE(*inptr1);
271  cr = GETJSAMPLE(*inptr2);
272  cred = Crrtab[cr];
273  cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
274  cblue = Cbbtab[cb];
275  y = GETJSAMPLE(*inptr0);
276  outptr[RGB_RED] = range_limit[y + cred];
277  outptr[RGB_GREEN] = range_limit[y + cgreen];
278  outptr[RGB_BLUE] = range_limit[y + cblue];
279  }
280 }
281 
282 
283 /*
284  * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
285  */
286 
287 METHODDEF void
288 h2v2_merged_upsample (j_decompress_ptr cinfo,
289  JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
290  JSAMPARRAY output_buf)
291 {
292  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
293  register int y, cred, cgreen, cblue;
294  int cb, cr;
295  register JSAMPROW outptr0, outptr1;
296  JSAMPROW inptr00, inptr01, inptr1, inptr2;
297  JDIMENSION col;
298  /* copy these pointers into registers if possible */
299  register JSAMPLE * range_limit = cinfo->sample_range_limit;
300  int * Crrtab = upsample->Cr_r_tab;
301  int * Cbbtab = upsample->Cb_b_tab;
302  INT32 * Crgtab = upsample->Cr_g_tab;
303  INT32 * Cbgtab = upsample->Cb_g_tab;
305 
306  inptr00 = input_buf[0][in_row_group_ctr*2];
307  inptr01 = input_buf[0][in_row_group_ctr*2 + 1];
308  inptr1 = input_buf[1][in_row_group_ctr];
309  inptr2 = input_buf[2][in_row_group_ctr];
310  outptr0 = output_buf[0];
311  outptr1 = output_buf[1];
312  /* Loop for each group of output pixels */
313  for (col = cinfo->output_width >> 1; col > 0; col--) {
314  /* Do the chroma part of the calculation */
315  cb = GETJSAMPLE(*inptr1++);
316  cr = GETJSAMPLE(*inptr2++);
317  cred = Crrtab[cr];
318  cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
319  cblue = Cbbtab[cb];
320  /* Fetch 4 Y values and emit 4 pixels */
321  y = GETJSAMPLE(*inptr00++);
322  outptr0[RGB_RED] = range_limit[y + cred];
323  outptr0[RGB_GREEN] = range_limit[y + cgreen];
324  outptr0[RGB_BLUE] = range_limit[y + cblue];
325  outptr0 += RGB_PIXELSIZE;
326  y = GETJSAMPLE(*inptr00++);
327  outptr0[RGB_RED] = range_limit[y + cred];
328  outptr0[RGB_GREEN] = range_limit[y + cgreen];
329  outptr0[RGB_BLUE] = range_limit[y + cblue];
330  outptr0 += RGB_PIXELSIZE;
331  y = GETJSAMPLE(*inptr01++);
332  outptr1[RGB_RED] = range_limit[y + cred];
333  outptr1[RGB_GREEN] = range_limit[y + cgreen];
334  outptr1[RGB_BLUE] = range_limit[y + cblue];
335  outptr1 += RGB_PIXELSIZE;
336  y = GETJSAMPLE(*inptr01++);
337  outptr1[RGB_RED] = range_limit[y + cred];
338  outptr1[RGB_GREEN] = range_limit[y + cgreen];
339  outptr1[RGB_BLUE] = range_limit[y + cblue];
340  outptr1 += RGB_PIXELSIZE;
341  }
342  /* If image width is odd, do the last output column separately */
343  if (cinfo->output_width & 1) {
344  cb = GETJSAMPLE(*inptr1);
345  cr = GETJSAMPLE(*inptr2);
346  cred = Crrtab[cr];
347  cgreen = (int) RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
348  cblue = Cbbtab[cb];
349  y = GETJSAMPLE(*inptr00);
350  outptr0[RGB_RED] = range_limit[y + cred];
351  outptr0[RGB_GREEN] = range_limit[y + cgreen];
352  outptr0[RGB_BLUE] = range_limit[y + cblue];
353  y = GETJSAMPLE(*inptr01);
354  outptr1[RGB_RED] = range_limit[y + cred];
355  outptr1[RGB_GREEN] = range_limit[y + cgreen];
356  outptr1[RGB_BLUE] = range_limit[y + cblue];
357  }
358 }
359 
360 
361 /*
362  * Module initialization routine for merged upsampling/color conversion.
363  *
364  * NB: this is called under the conditions determined by use_merged_upsample()
365  * in jdmaster.c. That routine MUST correspond to the actual capabilities
366  * of this module; no safety checks are made here.
367  */
368 
369 GLOBAL void
370 jinit_merged_upsampler (j_decompress_ptr cinfo)
371 {
372  my_upsample_ptr upsample;
373 
374  upsample = (my_upsample_ptr)
375  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
377  cinfo->upsample = (struct jpeg_upsampler *) upsample;
378  upsample->pub.start_pass = start_pass_merged_upsample;
379  upsample->pub.need_context_rows = FALSE;
380 
381  upsample->out_row_width = cinfo->output_width * cinfo->out_color_components;
382 
383  if (cinfo->max_v_samp_factor == 2) {
384  upsample->pub.upsample = merged_2v_upsample;
385  upsample->upmethod = h2v2_merged_upsample;
386  /* Allocate a spare row buffer */
387  upsample->spare_row = (JSAMPROW)
388  (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
389  (size_t) (upsample->out_row_width * SIZEOF(JSAMPLE)));
390  } else {
391  upsample->pub.upsample = merged_1v_upsample;
392  upsample->upmethod = h2v1_merged_upsample;
393  /* No spare row needed */
394  upsample->spare_row = NULL;
395  }
396 
397  build_ycc_rgb_table(cinfo);
398 }
399 
400 #endif /* UPSAMPLE_MERGING_SUPPORTED */
#define CENTERJSAMPLE
Definition: jmorecfg.h:74
char JSAMPLE
Definition: jmorecfg.h:64
JDIMENSION output_height
Definition: jpeglib.h:455
JSAMPLE FAR * JSAMPROW
Definition: jpeglib.h:79
GLOBAL void jcopy_sample_rows(JSAMPARRAY input_array, int source_row, JSAMPARRAY output_array, int dest_row, int num_rows, JDIMENSION num_cols)
Definition: jutils.c:107
#define SCALEBITS
Definition: jccolor.c:58
struct jpeg_common_struct * j_common_ptr
Definition: jpeglib.h:260
GLenum GLint GLint y
Definition: glext.h:2849
case const int
Definition: Callbacks.cpp:52
#define GETJSAMPLE(value)
Definition: jmorecfg.h:68
#define LOCAL
Definition: jmorecfg.h:189
JMETHOD(void, prepare_for_output_pass,(j_decompress_ptr cinfo))
JDIMENSION output_width
Definition: jpeglib.h:454
#define SIZEOF(object)
Definition: jinclude.h:80
#define MAXJSAMPLE
Definition: jmorecfg.h:73
struct jpeg_upsampler pub
Definition: jdsample.c:34
long INT32
Definition: jmorecfg.h:154
#define SHIFT_TEMPS
Definition: jpegint.h:287
GLenum GLint x
Definition: glext.h:2849
int i
Definition: process.py:33
#define JPOOL_IMAGE
Definition: jpeglib.h:736
JDIMENSION rows_to_go
Definition: jdsample.c:49
LOCAL void build_ycc_rgb_table(j_decompress_ptr cinfo)
Definition: jdcolor.c:70
#define ONE_HALF
Definition: jccolor.c:60
JSAMPLE * sample_range_limit
Definition: jpeglib.h:576
#define NULL
Definition: Lib.h:88
#define GLOBAL
Definition: jmorecfg.h:190
JSAMPARRAY * JSAMPIMAGE
Definition: jpeglib.h:81
#define METHODDEF
Definition: jmorecfg.h:188
JSAMPROW * JSAMPARRAY
Definition: jpeglib.h:80
my_upsampler * my_upsample_ptr
Definition: jdsample.c:61
#define FIX(x)
Definition: jccolor.c:61
struct jpeg_upsampler * upsample
Definition: jpeglib.h:614
#define RIGHT_SHIFT(x, shft)
Definition: jpegint.h:288
boolean need_context_rows
Definition: jpegint.h:240
#define FALSE
Definition: mprintf.c:70
unsigned int JDIMENSION
Definition: jmorecfg.h:177
#define TRUE
Definition: mprintf.c:69
if(!ValidDisplayID(prefInfo.prefDisplayID)) prefInfo.prefDisplayID