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/src/FreeImage/Source/LibJPEG/jdmerge.c

https://bitbucket.org/cabalistic/ogredeps/
C | 400 lines | 247 code | 46 blank | 107 comment | 15 complexity | 955b27a18c0d3da682da3d4c43dc8ffc MD5 | raw file
  1/*
  2 * jdmerge.c
  3 *
  4 * Copyright (C) 1994-1996, 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
 44typedef 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
 70typedef my_upsampler * my_upsample_ptr;
 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
 82LOCAL(void)
 83build_ycc_rgb_table (j_decompress_ptr cinfo)
 84{
 85  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
 86  int i;
 87  INT32 x;
 88  SHIFT_TEMPS
 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
125METHODDEF(void)
126start_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
143METHODDEF(void)
144merged_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
192METHODDEF(void)
193merged_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
225METHODDEF(void)
226h2v1_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;
242  SHIFT_TEMPS
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
287METHODDEF(void)
288h2v2_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;
304  SHIFT_TEMPS
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
369GLOBAL(void)
370jinit_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,
376				SIZEOF(my_upsampler));
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 */