4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1994-1996, Thomas G. Lane.
6 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
7 * libjpeg-turbo Modifications:
8 * Copyright (C) 2009, 2011, D. R. Commander.
9 * For conditions of distribution and use, see the accompanying README file.
11 * This file contains code for merged upsampling/color conversion.
13 * This file combines functions from jdsample.c and jdcolor.c;
14 * read those files first to understand what's going on.
16 * When the chroma components are to be upsampled by simple replication
17 * (ie, box filtering), we can save some work in color conversion by
18 * calculating all the output pixels corresponding to a pair of chroma
19 * samples at one time. In the conversion equations
21 * G = Y + K2 * Cb + K3 * Cr
23 * only the Y term varies among the group of pixels corresponding to a pair
24 * of chroma samples, so the rest of the terms can be calculated just once.
25 * At typical sampling ratios, this eliminates half or three-quarters of the
26 * multiplications needed for color conversion.
28 * This file currently provides implementations for the following cases:
29 * YCbCr => RGB color conversion only.
30 * Sampling ratios of 2h1v or 2h2v.
31 * No scaling needed at upsample time.
32 * Corner-aligned (non-CCIR601) sampling alignment.
33 * Other special cases could be added, but in most applications these are
34 * the only common cases. (For uncommon cases we fall back on the more
35 * general code in jdsample.c and jdcolor.c.)
38 #define JPEG_INTERNALS
44 #ifdef UPSAMPLE_MERGING_SUPPORTED
47 /* Private subobject */
50 struct jpeg_upsampler pub
; /* public fields */
52 /* Pointer to routine to do actual upsampling/conversion of one row group */
53 JMETHOD(void, upmethod
, (j_decompress_ptr cinfo
,
54 JSAMPIMAGE input_buf
, JDIMENSION in_row_group_ctr
,
55 JSAMPARRAY output_buf
));
57 /* Private state for YCC->RGB conversion */
58 int * Cr_r_tab
; /* => table for Cr to R conversion */
59 int * Cb_b_tab
; /* => table for Cb to B conversion */
60 INT32
* Cr_g_tab
; /* => table for Cr to G conversion */
61 INT32
* Cb_g_tab
; /* => table for Cb to G conversion */
63 /* For 2:1 vertical sampling, we produce two output rows at a time.
64 * We need a "spare" row buffer to hold the second output row if the
65 * application provides just a one-row buffer; we also use the spare
66 * to discard the dummy last row if the image height is odd.
69 boolean spare_full
; /* T if spare buffer is occupied */
71 JDIMENSION out_row_width
; /* samples per output row */
72 JDIMENSION rows_to_go
; /* counts rows remaining in image */
75 typedef my_upsampler
* my_upsample_ptr
;
77 #define SCALEBITS 16 /* speediest right-shift on some machines */
78 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
79 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
82 /* Include inline routines for colorspace extensions */
90 #define RGB_RED EXT_RGB_RED
91 #define RGB_GREEN EXT_RGB_GREEN
92 #define RGB_BLUE EXT_RGB_BLUE
93 #define RGB_PIXELSIZE EXT_RGB_PIXELSIZE
94 #define h2v1_merged_upsample_internal extrgb_h2v1_merged_upsample_internal
95 #define h2v2_merged_upsample_internal extrgb_h2v2_merged_upsample_internal
101 #undef h2v1_merged_upsample_internal
102 #undef h2v2_merged_upsample_internal
104 #define RGB_RED EXT_RGBX_RED
105 #define RGB_GREEN EXT_RGBX_GREEN
106 #define RGB_BLUE EXT_RGBX_BLUE
108 #define RGB_PIXELSIZE EXT_RGBX_PIXELSIZE
109 #define h2v1_merged_upsample_internal extrgbx_h2v1_merged_upsample_internal
110 #define h2v2_merged_upsample_internal extrgbx_h2v2_merged_upsample_internal
111 #include "jdmrgext.c"
117 #undef h2v1_merged_upsample_internal
118 #undef h2v2_merged_upsample_internal
120 #define RGB_RED EXT_BGR_RED
121 #define RGB_GREEN EXT_BGR_GREEN
122 #define RGB_BLUE EXT_BGR_BLUE
123 #define RGB_PIXELSIZE EXT_BGR_PIXELSIZE
124 #define h2v1_merged_upsample_internal extbgr_h2v1_merged_upsample_internal
125 #define h2v2_merged_upsample_internal extbgr_h2v2_merged_upsample_internal
126 #include "jdmrgext.c"
131 #undef h2v1_merged_upsample_internal
132 #undef h2v2_merged_upsample_internal
134 #define RGB_RED EXT_BGRX_RED
135 #define RGB_GREEN EXT_BGRX_GREEN
136 #define RGB_BLUE EXT_BGRX_BLUE
138 #define RGB_PIXELSIZE EXT_BGRX_PIXELSIZE
139 #define h2v1_merged_upsample_internal extbgrx_h2v1_merged_upsample_internal
140 #define h2v2_merged_upsample_internal extbgrx_h2v2_merged_upsample_internal
141 #include "jdmrgext.c"
147 #undef h2v1_merged_upsample_internal
148 #undef h2v2_merged_upsample_internal
150 #define RGB_RED EXT_XBGR_RED
151 #define RGB_GREEN EXT_XBGR_GREEN
152 #define RGB_BLUE EXT_XBGR_BLUE
154 #define RGB_PIXELSIZE EXT_XBGR_PIXELSIZE
155 #define h2v1_merged_upsample_internal extxbgr_h2v1_merged_upsample_internal
156 #define h2v2_merged_upsample_internal extxbgr_h2v2_merged_upsample_internal
157 #include "jdmrgext.c"
163 #undef h2v1_merged_upsample_internal
164 #undef h2v2_merged_upsample_internal
166 #define RGB_RED EXT_XRGB_RED
167 #define RGB_GREEN EXT_XRGB_GREEN
168 #define RGB_BLUE EXT_XRGB_BLUE
170 #define RGB_PIXELSIZE EXT_XRGB_PIXELSIZE
171 #define h2v1_merged_upsample_internal extxrgb_h2v1_merged_upsample_internal
172 #define h2v2_merged_upsample_internal extxrgb_h2v2_merged_upsample_internal
173 #include "jdmrgext.c"
179 #undef h2v1_merged_upsample_internal
180 #undef h2v2_merged_upsample_internal
184 * Initialize tables for YCC->RGB colorspace conversion.
185 * This is taken directly from jdcolor.c; see that file for more info.
189 build_ycc_rgb_table (j_decompress_ptr cinfo
)
191 my_upsample_ptr upsample
= (my_upsample_ptr
) cinfo
->upsample
;
196 upsample
->Cr_r_tab
= (int *)
197 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
198 (MAXJSAMPLE
+1) * SIZEOF(int));
199 upsample
->Cb_b_tab
= (int *)
200 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
201 (MAXJSAMPLE
+1) * SIZEOF(int));
202 upsample
->Cr_g_tab
= (INT32
*)
203 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
204 (MAXJSAMPLE
+1) * SIZEOF(INT32
));
205 upsample
->Cb_g_tab
= (INT32
*)
206 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
207 (MAXJSAMPLE
+1) * SIZEOF(INT32
));
209 for (i
= 0, x
= -CENTERJSAMPLE
; i
<= MAXJSAMPLE
; i
++, x
++) {
210 /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
211 /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
212 /* Cr=>R value is nearest int to 1.40200 * x */
213 upsample
->Cr_r_tab
[i
] = (int)
214 RIGHT_SHIFT(FIX(1.40200) * x
+ ONE_HALF
, SCALEBITS
);
215 /* Cb=>B value is nearest int to 1.77200 * x */
216 upsample
->Cb_b_tab
[i
] = (int)
217 RIGHT_SHIFT(FIX(1.77200) * x
+ ONE_HALF
, SCALEBITS
);
218 /* Cr=>G value is scaled-up -0.71414 * x */
219 upsample
->Cr_g_tab
[i
] = (- FIX(0.71414)) * x
;
220 /* Cb=>G value is scaled-up -0.34414 * x */
221 /* We also add in ONE_HALF so that need not do it in inner loop */
222 upsample
->Cb_g_tab
[i
] = (- FIX(0.34414)) * x
+ ONE_HALF
;
228 * Initialize for an upsampling pass.
232 start_pass_merged_upsample (j_decompress_ptr cinfo
)
234 my_upsample_ptr upsample
= (my_upsample_ptr
) cinfo
->upsample
;
236 /* Mark the spare buffer empty */
237 upsample
->spare_full
= FALSE
;
238 /* Initialize total-height counter for detecting bottom of image */
239 upsample
->rows_to_go
= cinfo
->output_height
;
244 * Control routine to do upsampling (and color conversion).
246 * The control routine just handles the row buffering considerations.
250 merged_2v_upsample (j_decompress_ptr cinfo
,
251 JSAMPIMAGE input_buf
, JDIMENSION
*in_row_group_ctr
,
252 JDIMENSION in_row_groups_avail
,
253 JSAMPARRAY output_buf
, JDIMENSION
*out_row_ctr
,
254 JDIMENSION out_rows_avail
)
255 /* 2:1 vertical sampling case: may need a spare row. */
257 my_upsample_ptr upsample
= (my_upsample_ptr
) cinfo
->upsample
;
258 JSAMPROW work_ptrs
[2];
259 JDIMENSION num_rows
; /* number of rows returned to caller */
261 if (upsample
->spare_full
) {
262 /* If we have a spare row saved from a previous cycle, just return it. */
263 jcopy_sample_rows(& upsample
->spare_row
, 0, output_buf
+ *out_row_ctr
, 0,
264 1, upsample
->out_row_width
);
266 upsample
->spare_full
= FALSE
;
268 /* Figure number of rows to return to caller. */
270 /* Not more than the distance to the end of the image. */
271 if (num_rows
> upsample
->rows_to_go
)
272 num_rows
= upsample
->rows_to_go
;
273 /* And not more than what the client can accept: */
274 out_rows_avail
-= *out_row_ctr
;
275 if (num_rows
> out_rows_avail
)
276 num_rows
= out_rows_avail
;
277 /* Create output pointer array for upsampler. */
278 work_ptrs
[0] = output_buf
[*out_row_ctr
];
280 work_ptrs
[1] = output_buf
[*out_row_ctr
+ 1];
282 work_ptrs
[1] = upsample
->spare_row
;
283 upsample
->spare_full
= TRUE
;
285 /* Now do the upsampling. */
286 (*upsample
->upmethod
) (cinfo
, input_buf
, *in_row_group_ctr
, work_ptrs
);
290 *out_row_ctr
+= num_rows
;
291 upsample
->rows_to_go
-= num_rows
;
292 /* When the buffer is emptied, declare this input row group consumed */
293 if (! upsample
->spare_full
)
294 (*in_row_group_ctr
)++;
299 merged_1v_upsample (j_decompress_ptr cinfo
,
300 JSAMPIMAGE input_buf
, JDIMENSION
*in_row_group_ctr
,
301 JDIMENSION in_row_groups_avail
,
302 JSAMPARRAY output_buf
, JDIMENSION
*out_row_ctr
,
303 JDIMENSION out_rows_avail
)
304 /* 1:1 vertical sampling case: much easier, never need a spare row. */
306 my_upsample_ptr upsample
= (my_upsample_ptr
) cinfo
->upsample
;
308 /* Just do the upsampling. */
309 (*upsample
->upmethod
) (cinfo
, input_buf
, *in_row_group_ctr
,
310 output_buf
+ *out_row_ctr
);
313 (*in_row_group_ctr
)++;
318 * These are the routines invoked by the control routines to do
319 * the actual upsampling/conversion. One row group is processed per call.
321 * Note: since we may be writing directly into application-supplied buffers,
322 * we have to be honest about the output width; we can't assume the buffer
323 * has been rounded up to an even width.
328 * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.
332 h2v1_merged_upsample (j_decompress_ptr cinfo
,
333 JSAMPIMAGE input_buf
, JDIMENSION in_row_group_ctr
,
334 JSAMPARRAY output_buf
)
336 switch (cinfo
->out_color_space
) {
338 extrgb_h2v1_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
343 extrgbx_h2v1_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
347 extbgr_h2v1_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
352 extbgrx_h2v1_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
357 extxbgr_h2v1_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
362 extxrgb_h2v1_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
366 h2v1_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
374 * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
378 h2v2_merged_upsample (j_decompress_ptr cinfo
,
379 JSAMPIMAGE input_buf
, JDIMENSION in_row_group_ctr
,
380 JSAMPARRAY output_buf
)
382 switch (cinfo
->out_color_space
) {
384 extrgb_h2v2_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
389 extrgbx_h2v2_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
393 extbgr_h2v2_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
398 extbgrx_h2v2_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
403 extxbgr_h2v2_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
408 extxrgb_h2v2_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
412 h2v2_merged_upsample_internal(cinfo
, input_buf
, in_row_group_ctr
,
420 * Module initialization routine for merged upsampling/color conversion.
422 * NB: this is called under the conditions determined by use_merged_upsample()
423 * in jdmaster.c. That routine MUST correspond to the actual capabilities
424 * of this module; no safety checks are made here.
428 jinit_merged_upsampler (j_decompress_ptr cinfo
)
430 my_upsample_ptr upsample
;
432 upsample
= (my_upsample_ptr
)
433 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
434 SIZEOF(my_upsampler
));
435 cinfo
->upsample
= (struct jpeg_upsampler
*) upsample
;
436 upsample
->pub
.start_pass
= start_pass_merged_upsample
;
437 upsample
->pub
.need_context_rows
= FALSE
;
439 upsample
->out_row_width
= cinfo
->output_width
* cinfo
->out_color_components
;
441 if (cinfo
->max_v_samp_factor
== 2) {
442 upsample
->pub
.upsample
= merged_2v_upsample
;
443 if (jsimd_can_h2v2_merged_upsample())
444 upsample
->upmethod
= jsimd_h2v2_merged_upsample
;
446 upsample
->upmethod
= h2v2_merged_upsample
;
447 /* Allocate a spare row buffer */
448 upsample
->spare_row
= (JSAMPROW
)
449 (*cinfo
->mem
->alloc_large
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
450 (size_t) (upsample
->out_row_width
* SIZEOF(JSAMPLE
)));
452 upsample
->pub
.upsample
= merged_1v_upsample
;
453 if (jsimd_can_h2v1_merged_upsample())
454 upsample
->upmethod
= jsimd_h2v1_merged_upsample
;
456 upsample
->upmethod
= h2v1_merged_upsample
;
457 /* No spare row needed */
458 upsample
->spare_row
= NULL
;
461 build_ycc_rgb_table(cinfo
);
464 #endif /* UPSAMPLE_MERGING_SUPPORTED */