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jdsample.c
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1 /*
2  * jdsample.c
3  *
4  * Copyright (C) 1991-1996, Thomas G. Lane.
5  * Modified 2002-2015 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 */
28 typedef JMETHOD(void, upsample1_ptr,
30  JSAMPARRAY input_data, JSAMPARRAY * output_data_ptr));
31 
32 /* Private subobject */
33 
34 typedef 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  */
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 
63 
64 
65 /*
66  * Initialize for an upsampling pass.
67  */
68 
69 METHODDEF(void)
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 
89 METHODDEF(void)
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;
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 
157 METHODDEF(void)
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 
170 METHODDEF(void)
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 
189 METHODDEF(void)
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 
233 METHODDEF(void)
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 
261 METHODDEF(void)
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 
293 GLOBAL(void)
295 {
296  my_upsample_ptr upsample;
297  int ci;
299  int h_in_group, v_in_group, h_out_group, v_out_group;
300 
301  upsample = (my_upsample_ptr)
302  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
304  cinfo->upsample = &upsample->pub;
305  upsample->pub.start_pass = start_pass_upsample;
306  upsample->pub.upsample = sep_upsample;
307  upsample->pub.need_context_rows = FALSE; /* until we find out differently */
308 
309  if (cinfo->CCIR601_sampling) /* this isn't supported */
310  ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
311 
312  /* Verify we can handle the sampling factors, select per-component methods,
313  * and create storage as needed.
314  */
315  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
316  ci++, compptr++) {
317  /* Compute size of an "input group" after IDCT scaling. This many samples
318  * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
319  */
320  h_in_group = (compptr->h_samp_factor * compptr->DCT_h_scaled_size) /
321  cinfo->min_DCT_h_scaled_size;
322  v_in_group = (compptr->v_samp_factor * compptr->DCT_v_scaled_size) /
323  cinfo->min_DCT_v_scaled_size;
324  h_out_group = cinfo->max_h_samp_factor;
325  v_out_group = cinfo->max_v_samp_factor;
326  upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
327  if (! compptr->component_needed) {
328  /* Don't bother to upsample an uninteresting component. */
329  upsample->methods[ci] = noop_upsample;
330  continue; /* don't need to allocate buffer */
331  }
332  if (h_in_group == h_out_group && v_in_group == v_out_group) {
333  /* Fullsize components can be processed without any work. */
334  upsample->methods[ci] = fullsize_upsample;
335  continue; /* don't need to allocate buffer */
336  }
337  if (h_in_group * 2 == h_out_group && v_in_group == v_out_group) {
338  /* Special case for 2h1v upsampling */
339  upsample->methods[ci] = h2v1_upsample;
340  } else if (h_in_group * 2 == h_out_group &&
341  v_in_group * 2 == v_out_group) {
342  /* Special case for 2h2v upsampling */
343  upsample->methods[ci] = h2v2_upsample;
344  } else if ((h_out_group % h_in_group) == 0 &&
345  (v_out_group % v_in_group) == 0) {
346  /* Generic integral-factors upsampling method */
347  upsample->methods[ci] = int_upsample;
348  upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group);
349  upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group);
350  } else
351  ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
352  upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
353  ((j_common_ptr) cinfo, JPOOL_IMAGE,
354  (JDIMENSION) jround_up((long) cinfo->output_width,
355  (long) cinfo->max_h_samp_factor),
356  (JDIMENSION) cinfo->max_v_samp_factor);
357  }
358 }
char JSAMPLE
Definition: jmorecfg.h:74
start_pass_upsample(j_decompress_ptr cinfo)
Definition: jdsample.c:70
noop_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
Definition: jdsample.c:171
JSAMPLE FAR * JSAMPROW
Definition: jpeglib.h:75
#define ERREXIT(msg)
Definition: rdjpgcom.c:72
upsample1_ptr methods[MAX_COMPONENTS]
Definition: jdsample.c:47
struct jpeg_common_struct * j_common_ptr
Definition: jpeglib.h:284
#define MAX_COMPONENTS
Definition: jmorecfg.h:45
JSAMPARRAY color_buf[MAX_COMPONENTS]
Definition: jdsample.c:44
int next_row_out
Definition: jdsample.c:49
jinit_upsampler(j_decompress_ptr cinfo)
Definition: jdsample.c:294
boolean component_needed
Definition: jpeglib.h:174
struct jpeg_upsampler pub
Definition: jdsample.c:35
GLfloat GLfloat GLfloat GLfloat h
Definition: glext.h:7723
jpeg_component_info * compptr
Definition: jdct.h:238
while(1)
Definition: macro.lex.yy.c:740
#define SIZEOF(_ar)
Definition: calc.h:97
#define JPOOL_IMAGE
Definition: jpeglib.h:808
JDIMENSION rows_to_go
Definition: jdsample.c:50
jround_up(long a, long b)
Definition: jutils.c:133
UINT8 v_expand[MAX_COMPONENTS]
Definition: jdsample.c:59
smooth NULL
Definition: ftsmooth.c:416
int rowgroup_height[MAX_COMPONENTS]
Definition: jdsample.c:53
int_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
Definition: jdsample.c:190
if(!(yy_init))
Definition: macro.lex.yy.c:714
int JSAMPARRAY int int num_rows
Definition: jpegint.h:412
JSAMPARRAY * JSAMPIMAGE
Definition: jpeglib.h:77
JSAMPROW * JSAMPARRAY
Definition: jpeglib.h:76
my_upsampler * my_upsample_ptr
Definition: jdsample.c:62
#define GLOBAL(type)
Definition: jmorecfg.h:291
#define METHODDEF(type)
Definition: jmorecfg.h:287
#define long
Definition: qsort.c:33
sep_upsample(j_decompress_ptr cinfo, JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr, JDIMENSION in_row_groups_avail, JSAMPARRAY output_buf, JDIMENSION *out_row_ctr, JDIMENSION out_rows_avail)
Definition: jdsample.c:90
UINT8 h_expand[MAX_COMPONENTS]
Definition: jdsample.c:58
jpeg_component_info JCOEFPTR JSAMPARRAY output_buf
Definition: jdct.h:238
unsigned int JDIMENSION
Definition: jmorecfg.h:229
h2v2_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
Definition: jdsample.c:262
h2v1_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
Definition: jdsample.c:234
fullsize_upsample(j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
Definition: jdsample.c:158
jcopy_sample_rows(JSAMPARRAY input_array, int source_row, JSAMPARRAY output_array, int dest_row, int num_rows, JDIMENSION num_cols)
Definition: jutils.c:177
unsigned char UINT8
typedef JMETHOD(void, upsample1_ptr,(j_decompress_ptr cinfo, jpeg_component_info *compptr, JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr))
unsigned int(__cdecl typeof(jpeg_read_scanlines))(struct jpeg_decompress_struct *
Definition: typeof.h:31