/media/libjpeg/jdsample.c

  1/*
  2 * jdsample.c
  3 *
  4 * Copyright (C) 1991-1996, Thomas G. Lane.
  5 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
  6 * Copyright (C) 2010, D. R. Commander.
  7 * This file is part of the Independent JPEG Group's software.
  8 * For conditions of distribution and use, see the accompanying README file.
  9 *
 10 * This file contains upsampling routines.
 11 *
 12 * Upsampling input data is counted in "row groups".  A row group
 13 * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
 14 * sample rows of each component.  Upsampling will normally produce
 15 * max_v_samp_factor pixel rows from each row group (but this could vary
 16 * if the upsampler is applying a scale factor of its own).
 17 *
 18 * An excellent reference for image resampling is
 19 *   Digital Image Warping, George Wolberg, 1990.
 20 *   Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
 21 */
 22
 23#define JPEG_INTERNALS
 24#include "jinclude.h"
 25#include "jpeglib.h"
 26#include "jsimd.h"
 27#include "jpegcomp.h"
 28
 29
 30/* Pointer to routine to upsample a single component */
 31typedef JMETHOD(void, upsample1_ptr,
 32		(j_decompress_ptr cinfo, jpeg_component_info * compptr,
 33		 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr));
 34
 35/* Private subobject */
 36
 37typedef struct {
 38  struct jpeg_upsampler pub;	/* public fields */
 39
 40  /* Color conversion buffer.  When using separate upsampling and color
 41   * conversion steps, this buffer holds one upsampled row group until it
 42   * has been color converted and output.
 43   * Note: we do not allocate any storage for component(s) which are full-size,
 44   * ie do not need rescaling.  The corresponding entry of color_buf[] is
 45   * simply set to point to the input data array, thereby avoiding copying.
 46   */
 47  JSAMPARRAY color_buf[MAX_COMPONENTS];
 48
 49  /* Per-component upsampling method pointers */
 50  upsample1_ptr methods[MAX_COMPONENTS];
 51
 52  int next_row_out;		/* counts rows emitted from color_buf */
 53  JDIMENSION rows_to_go;	/* counts rows remaining in image */
 54
 55  /* Height of an input row group for each component. */
 56  int rowgroup_height[MAX_COMPONENTS];
 57
 58  /* These arrays save pixel expansion factors so that int_expand need not
 59   * recompute them each time.  They are unused for other upsampling methods.
 60   */
 61  UINT8 h_expand[MAX_COMPONENTS];
 62  UINT8 v_expand[MAX_COMPONENTS];
 63} my_upsampler;
 64
 65typedef my_upsampler * my_upsample_ptr;
 66
 67
 68/*
 69 * Initialize for an upsampling pass.
 70 */
 71
 72METHODDEF(void)
 73start_pass_upsample (j_decompress_ptr cinfo)
 74{
 75  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
 76
 77  /* Mark the conversion buffer empty */
 78  upsample->next_row_out = cinfo->max_v_samp_factor;
 79  /* Initialize total-height counter for detecting bottom of image */
 80  upsample->rows_to_go = cinfo->output_height;
 81}
 82
 83
 84/*
 85 * Control routine to do upsampling (and color conversion).
 86 *
 87 * In this version we upsample each component independently.
 88 * We upsample one row group into the conversion buffer, then apply
 89 * color conversion a row at a time.
 90 */
 91
 92METHODDEF(void)
 93sep_upsample (j_decompress_ptr cinfo,
 94	      JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
 95	      JDIMENSION in_row_groups_avail,
 96	      JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
 97	      JDIMENSION out_rows_avail)
 98{
 99  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
100  int ci;
101  jpeg_component_info * compptr;
102  JDIMENSION num_rows;
103
104  /* Fill the conversion buffer, if it's empty */
105  if (upsample->next_row_out >= cinfo->max_v_samp_factor) {
106    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
107	 ci++, compptr++) {
108      /* Invoke per-component upsample method.  Notice we pass a POINTER
109       * to color_buf[ci], so that fullsize_upsample can change it.
110       */
111      (*upsample->methods[ci]) (cinfo, compptr,
112	input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]),
113	upsample->color_buf + ci);
114    }
115    upsample->next_row_out = 0;
116  }
117
118  /* Color-convert and emit rows */
119
120  /* How many we have in the buffer: */
121  num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out);
122  /* Not more than the distance to the end of the image.  Need this test
123   * in case the image height is not a multiple of max_v_samp_factor:
124   */
125  if (num_rows > upsample->rows_to_go) 
126    num_rows = upsample->rows_to_go;
127  /* And not more than what the client can accept: */
128  out_rows_avail -= *out_row_ctr;
129  if (num_rows > out_rows_avail)
130    num_rows = out_rows_avail;
131
132  (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf,
133				     (JDIMENSION) upsample->next_row_out,
134				     output_buf + *out_row_ctr,
135				     (int) num_rows);
136
137  /* Adjust counts */
138  *out_row_ctr += num_rows;
139  upsample->rows_to_go -= num_rows;
140  upsample->next_row_out += num_rows;
141  /* When the buffer is emptied, declare this input row group consumed */
142  if (upsample->next_row_out >= cinfo->max_v_samp_factor)
143    (*in_row_group_ctr)++;
144}
145
146
147/*
148 * These are the routines invoked by sep_upsample to upsample pixel values
149 * of a single component.  One row group is processed per call.
150 */
151
152
153/*
154 * For full-size components, we just make color_buf[ci] point at the
155 * input buffer, and thus avoid copying any data.  Note that this is
156 * safe only because sep_upsample doesn't declare the input row group
157 * "consumed" until we are done color converting and emitting it.
158 */
159
160METHODDEF(void)
161fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
162		   JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
163{
164  *output_data_ptr = input_data;
165}
166
167
168/*
169 * This is a no-op version used for "uninteresting" components.
170 * These components will not be referenced by color conversion.
171 */
172
173METHODDEF(void)
174noop_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
175	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
176{
177  *output_data_ptr = NULL;	/* safety check */
178}
179
180
181/*
182 * This version handles any integral sampling ratios.
183 * This is not used for typical JPEG files, so it need not be fast.
184 * Nor, for that matter, is it particularly accurate: the algorithm is
185 * simple replication of the input pixel onto the corresponding output
186 * pixels.  The hi-falutin sampling literature refers to this as a
187 * "box filter".  A box filter tends to introduce visible artifacts,
188 * so if you are actually going to use 3:1 or 4:1 sampling ratios
189 * you would be well advised to improve this code.
190 */
191
192METHODDEF(void)
193int_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
194	      JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
195{
196  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
197  JSAMPARRAY output_data = *output_data_ptr;
198  register JSAMPROW inptr, outptr;
199  register JSAMPLE invalue;
200  register int h;
201  JSAMPROW outend;
202  int h_expand, v_expand;
203  int inrow, outrow;
204
205  h_expand = upsample->h_expand[compptr->component_index];
206  v_expand = upsample->v_expand[compptr->component_index];
207
208  inrow = outrow = 0;
209  while (outrow < cinfo->max_v_samp_factor) {
210    /* Generate one output row with proper horizontal expansion */
211    inptr = input_data[inrow];
212    outptr = output_data[outrow];
213    outend = outptr + cinfo->output_width;
214    while (outptr < outend) {
215      invalue = *inptr++;	/* don't need GETJSAMPLE() here */
216      for (h = h_expand; h > 0; h--) {
217	*outptr++ = invalue;
218      }
219    }
220    /* Generate any additional output rows by duplicating the first one */
221    if (v_expand > 1) {
222      jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
223			v_expand-1, cinfo->output_width);
224    }
225    inrow++;
226    outrow += v_expand;
227  }
228}
229
230
231/*
232 * Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
233 * It's still a box filter.
234 */
235
236METHODDEF(void)
237h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
238	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
239{
240  JSAMPARRAY output_data = *output_data_ptr;
241  register JSAMPROW inptr, outptr;
242  register JSAMPLE invalue;
243  JSAMPROW outend;
244  int inrow;
245
246  for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
247    inptr = input_data[inrow];
248    outptr = output_data[inrow];
249    outend = outptr + cinfo->output_width;
250    while (outptr < outend) {
251      invalue = *inptr++;	/* don't need GETJSAMPLE() here */
252      *outptr++ = invalue;
253      *outptr++ = invalue;
254    }
255  }
256}
257
258
259/*
260 * Fast processing for the common case of 2:1 horizontal and 2:1 vertical.
261 * It's still a box filter.
262 */
263
264METHODDEF(void)
265h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
266	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
267{
268  JSAMPARRAY output_data = *output_data_ptr;
269  register JSAMPROW inptr, outptr;
270  register JSAMPLE invalue;
271  JSAMPROW outend;
272  int inrow, outrow;
273
274  inrow = outrow = 0;
275  while (outrow < cinfo->max_v_samp_factor) {
276    inptr = input_data[inrow];
277    outptr = output_data[outrow];
278    outend = outptr + cinfo->output_width;
279    while (outptr < outend) {
280      invalue = *inptr++;	/* don't need GETJSAMPLE() here */
281      *outptr++ = invalue;
282      *outptr++ = invalue;
283    }
284    jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
285		      1, cinfo->output_width);
286    inrow++;
287    outrow += 2;
288  }
289}
290
291
292/*
293 * Fancy processing for the common case of 2:1 horizontal and 1:1 vertical.
294 *
295 * The upsampling algorithm is linear interpolation between pixel centers,
296 * also known as a "triangle filter".  This is a good compromise between
297 * speed and visual quality.  The centers of the output pixels are 1/4 and 3/4
298 * of the way between input pixel centers.
299 *
300 * A note about the "bias" calculations: when rounding fractional values to
301 * integer, we do not want to always round 0.5 up to the next integer.
302 * If we did that, we'd introduce a noticeable bias towards larger values.
303 * Instead, this code is arranged so that 0.5 will be rounded up or down at
304 * alternate pixel locations (a simple ordered dither pattern).
305 */
306
307METHODDEF(void)
308h2v1_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
309		     JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
310{
311  JSAMPARRAY output_data = *output_data_ptr;
312  register JSAMPROW inptr, outptr;
313  register int invalue;
314  register JDIMENSION colctr;
315  int inrow;
316
317  for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
318    inptr = input_data[inrow];
319    outptr = output_data[inrow];
320    /* Special case for first column */
321    invalue = GETJSAMPLE(*inptr++);
322    *outptr++ = (JSAMPLE) invalue;
323    *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2);
324
325    for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
326      /* General case: 3/4 * nearer pixel + 1/4 * further pixel */
327      invalue = GETJSAMPLE(*inptr++) * 3;
328      *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2);
329      *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(*inptr) + 2) >> 2);
330    }
331
332    /* Special case for last column */
333    invalue = GETJSAMPLE(*inptr);
334    *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2);
335    *outptr++ = (JSAMPLE) invalue;
336  }
337}
338
339
340/*
341 * Fancy processing for the common case of 2:1 horizontal and 2:1 vertical.
342 * Again a triangle filter; see comments for h2v1 case, above.
343 *
344 * It is OK for us to reference the adjacent input rows because we demanded
345 * context from the main buffer controller (see initialization code).
346 */
347
348METHODDEF(void)
349h2v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
350		     JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
351{
352  JSAMPARRAY output_data = *output_data_ptr;
353  register JSAMPROW inptr0, inptr1, outptr;
354#if BITS_IN_JSAMPLE == 8
355  register int thiscolsum, lastcolsum, nextcolsum;
356#else
357  register INT32 thiscolsum, lastcolsum, nextcolsum;
358#endif
359  register JDIMENSION colctr;
360  int inrow, outrow, v;
361
362  inrow = outrow = 0;
363  while (outrow < cinfo->max_v_samp_factor) {
364    for (v = 0; v < 2; v++) {
365      /* inptr0 points to nearest input row, inptr1 points to next nearest */
366      inptr0 = input_data[inrow];
367      if (v == 0)		/* next nearest is row above */
368	inptr1 = input_data[inrow-1];
369      else			/* next nearest is row below */
370	inptr1 = input_data[inrow+1];
371      outptr = output_data[outrow++];
372
373      /* Special case for first column */
374      thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
375      nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
376      *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 8) >> 4);
377      *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
378      lastcolsum = thiscolsum; thiscolsum = nextcolsum;
379
380      for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
381	/* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */
382	/* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */
383	nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
384	*outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
385	*outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
386	lastcolsum = thiscolsum; thiscolsum = nextcolsum;
387      }
388
389      /* Special case for last column */
390      *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
391      *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 7) >> 4);
392    }
393    inrow++;
394  }
395}
396
397
398/*
399 * Module initialization routine for upsampling.
400 */
401
402GLOBAL(void)
403jinit_upsampler (j_decompress_ptr cinfo)
404{
405  my_upsample_ptr upsample;
406  int ci;
407  jpeg_component_info * compptr;
408  boolean need_buffer, do_fancy;
409  int h_in_group, v_in_group, h_out_group, v_out_group;
410
411  upsample = (my_upsample_ptr)
412    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
413				SIZEOF(my_upsampler));
414  cinfo->upsample = (struct jpeg_upsampler *) upsample;
415  upsample->pub.start_pass = start_pass_upsample;
416  upsample->pub.upsample = sep_upsample;
417  upsample->pub.need_context_rows = FALSE; /* until we find out differently */
418
419  if (cinfo->CCIR601_sampling)	/* this isn't supported */
420    ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
421
422  /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1,
423   * so don't ask for it.
424   */
425  do_fancy = cinfo->do_fancy_upsampling && cinfo->_min_DCT_scaled_size > 1;
426
427  /* Verify we can handle the sampling factors, select per-component methods,
428   * and create storage as needed.
429   */
430  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
431       ci++, compptr++) {
432    /* Compute size of an "input group" after IDCT scaling.  This many samples
433     * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
434     */
435    h_in_group = (compptr->h_samp_factor * compptr->_DCT_scaled_size) /
436		 cinfo->_min_DCT_scaled_size;
437    v_in_group = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
438		 cinfo->_min_DCT_scaled_size;
439    h_out_group = cinfo->max_h_samp_factor;
440    v_out_group = cinfo->max_v_samp_factor;
441    upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
442    need_buffer = TRUE;
443    if (! compptr->component_needed) {
444      /* Don't bother to upsample an uninteresting component. */
445      upsample->methods[ci] = noop_upsample;
446      need_buffer = FALSE;
447    } else if (h_in_group == h_out_group && v_in_group == v_out_group) {
448      /* Fullsize components can be processed without any work. */
449      upsample->methods[ci] = fullsize_upsample;
450      need_buffer = FALSE;
451    } else if (h_in_group * 2 == h_out_group &&
452	       v_in_group == v_out_group) {
453      /* Special cases for 2h1v upsampling */
454      if (do_fancy && compptr->downsampled_width > 2) {
455	if (jsimd_can_h2v1_fancy_upsample())
456	  upsample->methods[ci] = jsimd_h2v1_fancy_upsample;
457	else
458	  upsample->methods[ci] = h2v1_fancy_upsample;
459      } else {
460	if (jsimd_can_h2v1_upsample())
461	  upsample->methods[ci] = jsimd_h2v1_upsample;
462	else
463	  upsample->methods[ci] = h2v1_upsample;
464      }
465    } else if (h_in_group * 2 == h_out_group &&
466	       v_in_group * 2 == v_out_group) {
467      /* Special cases for 2h2v upsampling */
468      if (do_fancy && compptr->downsampled_width > 2) {
469	if (jsimd_can_h2v2_fancy_upsample())
470	  upsample->methods[ci] = jsimd_h2v2_fancy_upsample;
471	else
472	  upsample->methods[ci] = h2v2_fancy_upsample;
473	upsample->pub.need_context_rows = TRUE;
474      } else {
475	if (jsimd_can_h2v2_upsample())
476	  upsample->methods[ci] = jsimd_h2v2_upsample;
477	else
478	  upsample->methods[ci] = h2v2_upsample;
479      }
480    } else if ((h_out_group % h_in_group) == 0 &&
481	       (v_out_group % v_in_group) == 0) {
482      /* Generic integral-factors upsampling method */
483      upsample->methods[ci] = int_upsample;
484      upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group);
485      upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group);
486    } else
487      ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
488    if (need_buffer) {
489      upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
490	((j_common_ptr) cinfo, JPOOL_IMAGE,
491	 (JDIMENSION) jround_up((long) cinfo->output_width,
492				(long) cinfo->max_h_samp_factor),
493	 (JDIMENSION) cinfo->max_v_samp_factor);
494    }
495  }
496}