1/*
2 * jdsample.c
3 *
4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1991-1996, Thomas G. Lane.
6 * libjpeg-turbo Modifications:
7 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
8 * Copyright (C) 2010, 2015-2016, D. R. Commander.
9 * Copyright (C) 2014, MIPS Technologies, Inc., California.
10 * Copyright (C) 2015, Google, Inc.
11 * For conditions of distribution and use, see the accompanying README.ijg
12 * file.
13 *
14 * This file contains upsampling routines.
15 *
16 * Upsampling input data is counted in "row groups". A row group
17 * is defined to be (v_samp_factor * DCT_scaled_size / min_DCT_scaled_size)
18 * sample rows of each component. Upsampling will normally produce
19 * max_v_samp_factor pixel rows from each row group (but this could vary
20 * if the upsampler is applying a scale factor of its own).
21 *
22 * An excellent reference for image resampling is
23 * Digital Image Warping, George Wolberg, 1990.
24 * Pub. by IEEE Computer Society Press, Los Alamitos, CA. ISBN 0-8186-8944-7.
25 */
26
27#include "jinclude.h"
28#include "jdsample.h"
29#include "jsimd.h"
30#include "jpegcomp.h"
31
32
33
34/*
35 * Initialize for an upsampling pass.
36 */
37
38METHODDEF(void)
39start_pass_upsample (j_decompress_ptr cinfo)
40{
41 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
42
43 /* Mark the conversion buffer empty */
44 upsample->next_row_out = cinfo->max_v_samp_factor;
45 /* Initialize total-height counter for detecting bottom of image */
46 upsample->rows_to_go = cinfo->output_height;
47}
48
49
50/*
51 * Control routine to do upsampling (and color conversion).
52 *
53 * In this version we upsample each component independently.
54 * We upsample one row group into the conversion buffer, then apply
55 * color conversion a row at a time.
56 */
57
58METHODDEF(void)
59sep_upsample (j_decompress_ptr cinfo,
60 JSAMPIMAGE input_buf, JDIMENSION *in_row_group_ctr,
61 JDIMENSION in_row_groups_avail,
62 JSAMPARRAY output_buf, JDIMENSION *out_row_ctr,
63 JDIMENSION out_rows_avail)
64{
65 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
66 int ci;
67 jpeg_component_info *compptr;
68 JDIMENSION num_rows;
69
70 /* Fill the conversion buffer, if it's empty */
71 if (upsample->next_row_out >= cinfo->max_v_samp_factor) {
72 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
73 ci++, compptr++) {
74 /* Invoke per-component upsample method. Notice we pass a POINTER
75 * to color_buf[ci], so that fullsize_upsample can change it.
76 */
77 (*upsample->methods[ci]) (cinfo, compptr,
78 input_buf[ci] + (*in_row_group_ctr * upsample->rowgroup_height[ci]),
79 upsample->color_buf + ci);
80 }
81 upsample->next_row_out = 0;
82 }
83
84 /* Color-convert and emit rows */
85
86 /* How many we have in the buffer: */
87 num_rows = (JDIMENSION) (cinfo->max_v_samp_factor - upsample->next_row_out);
88 /* Not more than the distance to the end of the image. Need this test
89 * in case the image height is not a multiple of max_v_samp_factor:
90 */
91 if (num_rows > upsample->rows_to_go)
92 num_rows = upsample->rows_to_go;
93 /* And not more than what the client can accept: */
94 out_rows_avail -= *out_row_ctr;
95 if (num_rows > out_rows_avail)
96 num_rows = out_rows_avail;
97
98 (*cinfo->cconvert->color_convert) (cinfo, upsample->color_buf,
99 (JDIMENSION) upsample->next_row_out,
100 output_buf + *out_row_ctr,
101 (int) num_rows);
102
103 /* Adjust counts */
104 *out_row_ctr += num_rows;
105 upsample->rows_to_go -= num_rows;
106 upsample->next_row_out += num_rows;
107 /* When the buffer is emptied, declare this input row group consumed */
108 if (upsample->next_row_out >= cinfo->max_v_samp_factor)
109 (*in_row_group_ctr)++;
110}
111
112
113/*
114 * These are the routines invoked by sep_upsample to upsample pixel values
115 * of a single component. One row group is processed per call.
116 */
117
118
119/*
120 * For full-size components, we just make color_buf[ci] point at the
121 * input buffer, and thus avoid copying any data. Note that this is
122 * safe only because sep_upsample doesn't declare the input row group
123 * "consumed" until we are done color converting and emitting it.
124 */
125
126METHODDEF(void)
127fullsize_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr,
128 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
129{
130 *output_data_ptr = input_data;
131}
132
133
134/*
135 * This is a no-op version used for "uninteresting" components.
136 * These components will not be referenced by color conversion.
137 */
138
139METHODDEF(void)
140noop_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr,
141 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
142{
143 *output_data_ptr = NULL; /* safety check */
144}
145
146
147/*
148 * This version handles any integral sampling ratios.
149 * This is not used for typical JPEG files, so it need not be fast.
150 * Nor, for that matter, is it particularly accurate: the algorithm is
151 * simple replication of the input pixel onto the corresponding output
152 * pixels. The hi-falutin sampling literature refers to this as a
153 * "box filter". A box filter tends to introduce visible artifacts,
154 * so if you are actually going to use 3:1 or 4:1 sampling ratios
155 * you would be well advised to improve this code.
156 */
157
158METHODDEF(void)
159int_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr,
160 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
161{
162 my_upsample_ptr upsample = (my_upsample_ptr) cinfo->upsample;
163 JSAMPARRAY output_data = *output_data_ptr;
164 register JSAMPROW inptr, outptr;
165 register JSAMPLE invalue;
166 register int h;
167 JSAMPROW outend;
168 int h_expand, v_expand;
169 int inrow, outrow;
170
171 h_expand = upsample->h_expand[compptr->component_index];
172 v_expand = upsample->v_expand[compptr->component_index];
173
174 inrow = outrow = 0;
175 while (outrow < cinfo->max_v_samp_factor) {
176 /* Generate one output row with proper horizontal expansion */
177 inptr = input_data[inrow];
178 outptr = output_data[outrow];
179 outend = outptr + cinfo->output_width;
180 while (outptr < outend) {
181 invalue = *inptr++; /* don't need GETJSAMPLE() here */
182 for (h = h_expand; h > 0; h--) {
183 *outptr++ = invalue;
184 }
185 }
186 /* Generate any additional output rows by duplicating the first one */
187 if (v_expand > 1) {
188 jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
189 v_expand-1, cinfo->output_width);
190 }
191 inrow++;
192 outrow += v_expand;
193 }
194}
195
196
197/*
198 * Fast processing for the common case of 2:1 horizontal and 1:1 vertical.
199 * It's still a box filter.
200 */
201
202METHODDEF(void)
203h2v1_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr,
204 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
205{
206 JSAMPARRAY output_data = *output_data_ptr;
207 register JSAMPROW inptr, outptr;
208 register JSAMPLE invalue;
209 JSAMPROW outend;
210 int inrow;
211
212 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
213 inptr = input_data[inrow];
214 outptr = output_data[inrow];
215 outend = outptr + cinfo->output_width;
216 while (outptr < outend) {
217 invalue = *inptr++; /* don't need GETJSAMPLE() here */
218 *outptr++ = invalue;
219 *outptr++ = invalue;
220 }
221 }
222}
223
224
225/*
226 * Fast processing for the common case of 2:1 horizontal and 2:1 vertical.
227 * It's still a box filter.
228 */
229
230METHODDEF(void)
231h2v2_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr,
232 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
233{
234 JSAMPARRAY output_data = *output_data_ptr;
235 register JSAMPROW inptr, outptr;
236 register JSAMPLE invalue;
237 JSAMPROW outend;
238 int inrow, outrow;
239
240 inrow = outrow = 0;
241 while (outrow < cinfo->max_v_samp_factor) {
242 inptr = input_data[inrow];
243 outptr = output_data[outrow];
244 outend = outptr + cinfo->output_width;
245 while (outptr < outend) {
246 invalue = *inptr++; /* don't need GETJSAMPLE() here */
247 *outptr++ = invalue;
248 *outptr++ = invalue;
249 }
250 jcopy_sample_rows(output_data, outrow, output_data, outrow+1,
251 1, cinfo->output_width);
252 inrow++;
253 outrow += 2;
254 }
255}
256
257
258/*
259 * Fancy processing for the common case of 2:1 horizontal and 1:1 vertical.
260 *
261 * The upsampling algorithm is linear interpolation between pixel centers,
262 * also known as a "triangle filter". This is a good compromise between
263 * speed and visual quality. The centers of the output pixels are 1/4 and 3/4
264 * of the way between input pixel centers.
265 *
266 * A note about the "bias" calculations: when rounding fractional values to
267 * integer, we do not want to always round 0.5 up to the next integer.
268 * If we did that, we'd introduce a noticeable bias towards larger values.
269 * Instead, this code is arranged so that 0.5 will be rounded up or down at
270 * alternate pixel locations (a simple ordered dither pattern).
271 */
272
273METHODDEF(void)
274h2v1_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr,
275 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
276{
277 JSAMPARRAY output_data = *output_data_ptr;
278 register JSAMPROW inptr, outptr;
279 register int invalue;
280 register JDIMENSION colctr;
281 int inrow;
282
283 for (inrow = 0; inrow < cinfo->max_v_samp_factor; inrow++) {
284 inptr = input_data[inrow];
285 outptr = output_data[inrow];
286 /* Special case for first column */
287 invalue = GETJSAMPLE(*inptr++);
288 *outptr++ = (JSAMPLE) invalue;
289 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(*inptr) + 2) >> 2);
290
291 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
292 /* General case: 3/4 * nearer pixel + 1/4 * further pixel */
293 invalue = GETJSAMPLE(*inptr++) * 3;
294 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(inptr[-2]) + 1) >> 2);
295 *outptr++ = (JSAMPLE) ((invalue + GETJSAMPLE(*inptr) + 2) >> 2);
296 }
297
298 /* Special case for last column */
299 invalue = GETJSAMPLE(*inptr);
300 *outptr++ = (JSAMPLE) ((invalue * 3 + GETJSAMPLE(inptr[-1]) + 1) >> 2);
301 *outptr++ = (JSAMPLE) invalue;
302 }
303}
304
305
306/*
307 * Fancy processing for the common case of 2:1 horizontal and 2:1 vertical.
308 * Again a triangle filter; see comments for h2v1 case, above.
309 *
310 * It is OK for us to reference the adjacent input rows because we demanded
311 * context from the main buffer controller (see initialization code).
312 */
313
314METHODDEF(void)
315h2v2_fancy_upsample (j_decompress_ptr cinfo, jpeg_component_info *compptr,
316 JSAMPARRAY input_data, JSAMPARRAY *output_data_ptr)
317{
318 JSAMPARRAY output_data = *output_data_ptr;
319 register JSAMPROW inptr0, inptr1, outptr;
320#if BITS_IN_JSAMPLE == 8
321 register int thiscolsum, lastcolsum, nextcolsum;
322#else
323 register JLONG thiscolsum, lastcolsum, nextcolsum;
324#endif
325 register JDIMENSION colctr;
326 int inrow, outrow, v;
327
328 inrow = outrow = 0;
329 while (outrow < cinfo->max_v_samp_factor) {
330 for (v = 0; v < 2; v++) {
331 /* inptr0 points to nearest input row, inptr1 points to next nearest */
332 inptr0 = input_data[inrow];
333 if (v == 0) /* next nearest is row above */
334 inptr1 = input_data[inrow-1];
335 else /* next nearest is row below */
336 inptr1 = input_data[inrow+1];
337 outptr = output_data[outrow++];
338
339 /* Special case for first column */
340 thiscolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
341 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
342 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 8) >> 4);
343 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
344 lastcolsum = thiscolsum; thiscolsum = nextcolsum;
345
346 for (colctr = compptr->downsampled_width - 2; colctr > 0; colctr--) {
347 /* General case: 3/4 * nearer pixel + 1/4 * further pixel in each */
348 /* dimension, thus 9/16, 3/16, 3/16, 1/16 overall */
349 nextcolsum = GETJSAMPLE(*inptr0++) * 3 + GETJSAMPLE(*inptr1++);
350 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
351 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + nextcolsum + 7) >> 4);
352 lastcolsum = thiscolsum; thiscolsum = nextcolsum;
353 }
354
355 /* Special case for last column */
356 *outptr++ = (JSAMPLE) ((thiscolsum * 3 + lastcolsum + 8) >> 4);
357 *outptr++ = (JSAMPLE) ((thiscolsum * 4 + 7) >> 4);
358 }
359 inrow++;
360 }
361}
362
363
364/*
365 * Module initialization routine for upsampling.
366 */
367
368GLOBAL(void)
369jinit_upsampler (j_decompress_ptr cinfo)
370{
371 my_upsample_ptr upsample;
372 int ci;
373 jpeg_component_info *compptr;
374 boolean need_buffer, do_fancy;
375 int h_in_group, v_in_group, h_out_group, v_out_group;
376
377 if (!cinfo->master->jinit_upsampler_no_alloc) {
378 upsample = (my_upsample_ptr)
379 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
380 sizeof(my_upsampler));
381 cinfo->upsample = (struct jpeg_upsampler *) upsample;
382 upsample->pub.start_pass = start_pass_upsample;
383 upsample->pub.upsample = sep_upsample;
384 upsample->pub.need_context_rows = FALSE; /* until we find out differently */
385 } else
386 upsample = (my_upsample_ptr) cinfo->upsample;
387
388 if (cinfo->CCIR601_sampling) /* this isn't supported */
389 ERREXIT(cinfo, JERR_CCIR601_NOTIMPL);
390
391 /* jdmainct.c doesn't support context rows when min_DCT_scaled_size = 1,
392 * so don't ask for it.
393 */
394 do_fancy = cinfo->do_fancy_upsampling && cinfo->_min_DCT_scaled_size > 1;
395
396 /* Verify we can handle the sampling factors, select per-component methods,
397 * and create storage as needed.
398 */
399 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
400 ci++, compptr++) {
401 /* Compute size of an "input group" after IDCT scaling. This many samples
402 * are to be converted to max_h_samp_factor * max_v_samp_factor pixels.
403 */
404 h_in_group = (compptr->h_samp_factor * compptr->_DCT_scaled_size) /
405 cinfo->_min_DCT_scaled_size;
406 v_in_group = (compptr->v_samp_factor * compptr->_DCT_scaled_size) /
407 cinfo->_min_DCT_scaled_size;
408 h_out_group = cinfo->max_h_samp_factor;
409 v_out_group = cinfo->max_v_samp_factor;
410 upsample->rowgroup_height[ci] = v_in_group; /* save for use later */
411 need_buffer = TRUE;
412 if (! compptr->component_needed) {
413 /* Don't bother to upsample an uninteresting component. */
414 upsample->methods[ci] = noop_upsample;
415 need_buffer = FALSE;
416 } else if (h_in_group == h_out_group && v_in_group == v_out_group) {
417 /* Fullsize components can be processed without any work. */
418 upsample->methods[ci] = fullsize_upsample;
419 need_buffer = FALSE;
420 } else if (h_in_group * 2 == h_out_group &&
421 v_in_group == v_out_group) {
422 /* Special cases for 2h1v upsampling */
423 if (do_fancy && compptr->downsampled_width > 2) {
424 if (jsimd_can_h2v1_fancy_upsample())
425 upsample->methods[ci] = jsimd_h2v1_fancy_upsample;
426 else
427 upsample->methods[ci] = h2v1_fancy_upsample;
428 } else {
429 if (jsimd_can_h2v1_upsample())
430 upsample->methods[ci] = jsimd_h2v1_upsample;
431 else
432 upsample->methods[ci] = h2v1_upsample;
433 }
434 } else if (h_in_group * 2 == h_out_group &&
435 v_in_group * 2 == v_out_group) {
436 /* Special cases for 2h2v upsampling */
437 if (do_fancy && compptr->downsampled_width > 2) {
438 if (jsimd_can_h2v2_fancy_upsample())
439 upsample->methods[ci] = jsimd_h2v2_fancy_upsample;
440 else
441 upsample->methods[ci] = h2v2_fancy_upsample;
442 upsample->pub.need_context_rows = TRUE;
443 } else {
444 if (jsimd_can_h2v2_upsample())
445 upsample->methods[ci] = jsimd_h2v2_upsample;
446 else
447 upsample->methods[ci] = h2v2_upsample;
448 }
449 } else if ((h_out_group % h_in_group) == 0 &&
450 (v_out_group % v_in_group) == 0) {
451 /* Generic integral-factors upsampling method */
452#if defined(__mips__)
453 if (jsimd_can_int_upsample())
454 upsample->methods[ci] = jsimd_int_upsample;
455 else
456#endif
457 upsample->methods[ci] = int_upsample;
458 upsample->h_expand[ci] = (UINT8) (h_out_group / h_in_group);
459 upsample->v_expand[ci] = (UINT8) (v_out_group / v_in_group);
460 } else
461 ERREXIT(cinfo, JERR_FRACT_SAMPLE_NOTIMPL);
462 if (need_buffer && !cinfo->master->jinit_upsampler_no_alloc) {
463 upsample->color_buf[ci] = (*cinfo->mem->alloc_sarray)
464 ((j_common_ptr) cinfo, JPOOL_IMAGE,
465 (JDIMENSION) jround_up((long) cinfo->output_width,
466 (long) cinfo->max_h_samp_factor),
467 (JDIMENSION) cinfo->max_v_samp_factor);
468 }
469 }
470}
471