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/src/FreeImage/Source/LibJPEG/jdsample.c

https://bitbucket.org/cabalistic/ogredeps/
C | 361 lines | 205 code | 50 blank | 106 comment | 34 complexity | e191d4d65b568fa8af838efbb26c11f7 MD5 | raw file
  1/*
  2 * jdsample.c
  3 *
  4 * Copyright (C) 1991-1996, Thomas G. Lane.
  5 * Modified 2002-2008 by Guido Vollbeding.
  6 * This file is part of the Independent JPEG Group's software.
  7 * For conditions of distribution and use, see the accompanying README file.
  8 *
  9 * This file contains upsampling routines.
 10 *
 11 * Upsampling input data is counted in "row groups".  A row group
 12 * is defined to be (v_samp_factor * DCT_v_scaled_size / min_DCT_v_scaled_size)
 13 * sample rows of each component.  Upsampling will normally produce
 14 * max_v_samp_factor pixel rows from each row group (but this could vary
 15 * if the upsampler is applying a scale factor of its own).
 16 *
 17 * An excellent reference for image resampling is
 18 *   Digital Image Warping, George Wolberg, 1990.
 19 *   Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
 20 */
 21
 22#define JPEG_INTERNALS
 23#include "jinclude.h"
 24#include "jpeglib.h"
 25
 26
 27/* Pointer to routine to upsample a single component */
 28typedef JMETHOD(void, upsample1_ptr,
 29		(j_decompress_ptr cinfo, jpeg_component_info * compptr,
 30		 JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr));
 31
 32/* Private subobject */
 33
 34typedef struct {
 35  struct jpeg_upsampler pub;	/* public fields */
 36
 37  /* Color conversion buffer.  When using separate upsampling and color
 38   * conversion steps, this buffer holds one upsampled row group until it
 39   * has been color converted and output.
 40   * Note: we do not allocate any storage for component(s) which are full-size,
 41   * ie do not need rescaling.  The corresponding entry of color_buf[] is
 42   * simply set to point to the input data array, thereby avoiding copying.
 43   */
 44  JSAMPARRAY color_buf[MAX_COMPONENTS];
 45
 46  /* Per-component upsampling method pointers */
 47  upsample1_ptr methods[MAX_COMPONENTS];
 48
 49  int next_row_out;		/* counts rows emitted from color_buf */
 50  JDIMENSION rows_to_go;	/* counts rows remaining in image */
 51
 52  /* Height of an input row group for each component. */
 53  int rowgroup_height[MAX_COMPONENTS];
 54
 55  /* These arrays save pixel expansion factors so that int_expand need not
 56   * recompute them each time.  They are unused for other upsampling methods.
 57   */
 58  UINT8 h_expand[MAX_COMPONENTS];
 59  UINT8 v_expand[MAX_COMPONENTS];
 60} my_upsampler;
 61
 62typedef my_upsampler * my_upsample_ptr;
 63
 64
 65/*
 66 * Initialize for an upsampling pass.
 67 */
 68
 69METHODDEF(void)
 70start_pass_upsample (j_decompress_ptr cinfo)
 71{
 72  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
 73
 74  /* Mark the conversion buffer empty */
 75  upsample->next_row_out = cinfo->max_v_samp_factor;
 76  /* Initialize total-height counter for detecting bottom of image */
 77  upsample->rows_to_go = cinfo->output_height;
 78}
 79
 80
 81/*
 82 * Control routine to do upsampling (and color conversion).
 83 *
 84 * In this version we upsample each component independently.
 85 * We upsample one row group into the conversion buffer, then apply
 86 * color conversion a row at a time.
 87 */
 88
 89METHODDEF(void)
 90sep_upsample (j_decompress_ptr cinfo,
 91	      JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
 92	      JDIMENSION in_row_groups_avail,
 93	      JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
 94	      JDIMENSION out_rows_avail)
 95{
 96  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
 97  int ci;
 98  jpeg_component_info * compptr;
 99  JDIMENSION num_rows;
100
101  /* Fill the conversion buffer, if it's empty */
102  if (upsample->next_row_out >= cinfo->max_v_samp_factor) {
103    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
104	 ci++, compptr++) {
105      /* Invoke per-component upsample method.  Notice we pass a POINTER
106       * to color_buf[ci], so that fullsize_upsample can change it.
107       */
108      (*upsample->methods[ci]) (cinfo, compptr,
109	input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]),
110	upsample->color_buf + ci);
111    }
112    upsample->next_row_out = 0;
113  }
114
115  /* Color-convert and emit rows */
116
117  /* How many we have in the buffer: */
118  num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out);
119  /* Not more than the distance to the end of the image.  Need this test
120   * in case the image height is not a multiple of max_v_samp_factor:
121   */
122  if (num_rows > upsample->rows_to_go) 
123    num_rows = upsample->rows_to_go;
124  /* And not more than what the client can accept: */
125  out_rows_avail -= *out_row_ctr;
126  if (num_rows > out_rows_avail)
127    num_rows = out_rows_avail;
128
129  (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf,
130				     (JDIMENSION) upsample->next_row_out,
131				     output_buf + *out_row_ctr,
132				     (int) num_rows);
133
134  /* Adjust counts */
135  *out_row_ctr += num_rows;
136  upsample->rows_to_go -= num_rows;
137  upsample->next_row_out += num_rows;
138  /* When the buffer is emptied, declare this input row group consumed */
139  if (upsample->next_row_out >= cinfo->max_v_samp_factor)
140    (*in_row_group_ctr)++;
141}
142
143
144/*
145 * These are the routines invoked by sep_upsample to upsample pixel values
146 * of a single component.  One row group is processed per call.
147 */
148
149
150/*
151 * For full-size components, we just make color_buf[ci] point at the
152 * input buffer, and thus avoid copying any data.  Note that this is
153 * safe only because sep_upsample doesn't declare the input row group
154 * "consumed" until we are done color converting and emitting it.
155 */
156
157METHODDEF(void)
158fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
159		   JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
160{
161  *output_data_ptr = input_data;
162}
163
164
165/*
166 * This is a no-op version used for "uninteresting" components.
167 * These components will not be referenced by color conversion.
168 */
169
170METHODDEF(void)
171noop_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
172	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
173{
174  *output_data_ptr = NULL;	/* safety check */
175}
176
177
178/*
179 * This version handles any integral sampling ratios.
180 * This is not used for typical JPEG files, so it need not be fast.
181 * Nor, for that matter, is it particularly accurate: the algorithm is
182 * simple replication of the input pixel onto the corresponding output
183 * pixels.  The hi-falutin sampling literature refers to this as a
184 * "box filter".  A box filter tends to introduce visible artifacts,
185 * so if you are actually going to use 3:1 or 4:1 sampling ratios
186 * you would be well advised to improve this code.
187 */
188
189METHODDEF(void)
190int_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
191	      JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
192{
193  my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
194  JSAMPARRAY output_data = *output_data_ptr;
195  register JSAMPROW inptr, outptr;
196  register JSAMPLE invalue;
197  register int h;
198  JSAMPROW outend;
199  int h_expand, v_expand;
200  int inrow, outrow;
201
202  h_expand = upsample->h_expand[compptr->component_index];
203  v_expand = upsample->v_expand[compptr->component_index];
204
205  inrow = outrow = 0;
206  while (outrow < cinfo->max_v_samp_factor) {
207    /* Generate one output row with proper horizontal expansion */
208    inptr = input_data[inrow];
209    outptr = output_data[outrow];
210    outend = outptr + cinfo->output_width;
211    while (outptr < outend) {
212      invalue = *inptr++;	/* don't need GETJSAMPLE() here */
213      for (h = h_expand; h > 0; h--) {
214	*outptr++ = invalue;
215      }
216    }
217    /* Generate any additional output rows by duplicating the first one */
218    if (v_expand > 1) {
219      jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
220			v_expand-1, cinfo->output_width);
221    }
222    inrow++;
223    outrow += v_expand;
224  }
225}
226
227
228/*
229 * Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
230 * It's still a box filter.
231 */
232
233METHODDEF(void)
234h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
235	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
236{
237  JSAMPARRAY output_data = *output_data_ptr;
238  register JSAMPROW inptr, outptr;
239  register JSAMPLE invalue;
240  JSAMPROW outend;
241  int outrow;
242
243  for (outrow = 0; outrow < cinfo->max_v_samp_factor; outrow++) {
244    inptr = input_data[outrow];
245    outptr = output_data[outrow];
246    outend = outptr + cinfo->output_width;
247    while (outptr < outend) {
248      invalue = *inptr++;	/* don't need GETJSAMPLE() here */
249      *outptr++ = invalue;
250      *outptr++ = invalue;
251    }
252  }
253}
254
255
256/*
257 * Fast processing for the common case of 2:1 horizontal and 2:1 vertical.
258 * It's still a box filter.
259 */
260
261METHODDEF(void)
262h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info * compptr,
263	       JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr)
264{
265  JSAMPARRAY output_data = *output_data_ptr;
266  register JSAMPROW inptr, outptr;
267  register JSAMPLE invalue;
268  JSAMPROW outend;
269  int inrow, outrow;
270
271  inrow = outrow = 0;
272  while (outrow < cinfo->max_v_samp_factor) {
273    inptr = input_data[inrow];
274    outptr = output_data[outrow];
275    outend = outptr + cinfo->output_width;
276    while (outptr < outend) {
277      invalue = *inptr++;	/* don't need GETJSAMPLE() here */
278      *outptr++ = invalue;
279      *outptr++ = invalue;
280    }
281    jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
282		      1, cinfo->output_width);
283    inrow++;
284    outrow += 2;
285  }
286}
287
288
289/*
290 * Module initialization routine for upsampling.
291 */
292
293GLOBAL(void)
294jinit_upsampler (j_decompress_ptr cinfo)
295{
296  my_upsample_ptr upsample;
297  int ci;
298  jpeg_component_info * compptr;
299  boolean need_buffer;
300  int h_in_group, v_in_group, h_out_group, v_out_group;
301
302  upsample = (my_upsample_ptr)
303    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
304				SIZEOF(my_upsampler));
305  cinfo->upsample = (struct jpeg_upsampler *) upsample;
306  upsample->pub.start_pass = start_pass_upsample;
307  upsample->pub.upsample = sep_upsample;
308  upsample->pub.need_context_rows = FALSE; /* until we find out differently */
309
310  if (cinfo->CCIR601_sampling)	/* this isn't supported */
311    ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
312
313  /* Verify we can handle the sampling factors, select per-component methods,
314   * and create storage as needed.
315   */
316  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
317       ci++, compptr++) {
318    /* Compute size of an "input group" after IDCT scaling.  This many samples
319     * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
320     */
321    h_in_group = (compptr->h_samp_factor * compptr->DCT_h_scaled_size) /
322		 cinfo->min_DCT_h_scaled_size;
323    v_in_group = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) /
324		 cinfo->min_DCT_v_scaled_size;
325    h_out_group = cinfo->max_h_samp_factor;
326    v_out_group = cinfo->max_v_samp_factor;
327    upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
328    need_buffer = TRUE;
329    if (! compptr->component_needed) {
330      /* Don't bother to upsample an uninteresting component. */
331      upsample->methods[ci] = noop_upsample;
332      need_buffer = FALSE;
333    } else if (h_in_group == h_out_group && v_in_group == v_out_group) {
334      /* Fullsize components can be processed without any work. */
335      upsample->methods[ci] = fullsize_upsample;
336      need_buffer = FALSE;
337    } else if (h_in_group * 2 == h_out_group &&
338	       v_in_group == v_out_group) {
339      /* Special case for 2h1v upsampling */
340      upsample->methods[ci] = h2v1_upsample;
341    } else if (h_in_group * 2 == h_out_group &&
342	       v_in_group * 2 == v_out_group) {
343      /* Special case for 2h2v upsampling */
344      upsample->methods[ci] = h2v2_upsample;
345    } else if ((h_out_group % h_in_group) == 0 &&
346	       (v_out_group % v_in_group) == 0) {
347      /* Generic integral-factors upsampling method */
348      upsample->methods[ci] = int_upsample;
349      upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group);
350      upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group);
351    } else
352      ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
353    if (need_buffer) {
354      upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
355	((j_common_ptr) cinfo, JPOOL_IMAGE,
356	 (JDIMENSION) jround_up((long) cinfo->output_width,
357				(long) cinfo->max_h_samp_factor),
358	 (JDIMENSION) cinfo->max_v_samp_factor);
359    }
360  }
361}