/[pcsx2_0.9.7]/trunk/3rdparty/libjpeg/jdsample.c
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Contents of /trunk/3rdparty/libjpeg/jdsample.c

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Revision 10 - (show annotations) (download)
Mon Sep 6 11:40:06 2010 UTC (9 years, 10 months ago) by william
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exported r3113 from ./upstream/trunk
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 */
28 typedef 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
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 */
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
62 typedef my_upsampler * my_upsample_ptr;
63
64
65 /*
66 * Initialize for an upsampling pass.
67 */
68
69 METHODDEF(void)
70 start_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
89 METHODDEF(void)
90 sep_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
157 METHODDEF(void)
158 fullsize_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
170 METHODDEF(void)
171 noop_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
189 METHODDEF(void)
190 int_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
233 METHODDEF(void)
234 h2v1_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
261 METHODDEF(void)
262 h2v2_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
293 GLOBAL(void)
294 jinit_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 }

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