4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1991-1997, Thomas G. Lane.
6 * Modified 2011 by Guido Vollbeding.
7 * libjpeg-turbo Modifications:
8 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
9 * Copyright (C) 2009, 2011-2012, D. R. Commander.
10 * For conditions of distribution and use, see the accompanying README file.
12 * This file contains output colorspace conversion routines.
15 #define JPEG_INTERNALS
22 /* Private subobject */
25 struct jpeg_color_deconverter pub
; /* public fields */
27 /* Private state for YCC->RGB conversion */
28 int * Cr_r_tab
; /* => table for Cr to R conversion */
29 int * Cb_b_tab
; /* => table for Cb to B conversion */
30 INT32
* Cr_g_tab
; /* => table for Cr to G conversion */
31 INT32
* Cb_g_tab
; /* => table for Cb to G conversion */
33 /* Private state for RGB->Y conversion */
34 INT32
* rgb_y_tab
; /* => table for RGB to Y conversion */
35 } my_color_deconverter
;
37 typedef my_color_deconverter
* my_cconvert_ptr
;
40 /**************** YCbCr -> RGB conversion: most common case **************/
41 /**************** RGB -> Y conversion: less common case **************/
44 * YCbCr is defined per CCIR 601-1, except that Cb and Cr are
45 * normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
46 * The conversion equations to be implemented are therefore
48 * R = Y + 1.40200 * Cr
49 * G = Y - 0.34414 * Cb - 0.71414 * Cr
50 * B = Y + 1.77200 * Cb
52 * Y = 0.29900 * R + 0.58700 * G + 0.11400 * B
54 * where Cb and Cr represent the incoming values less CENTERJSAMPLE.
55 * (These numbers are derived from TIFF 6.0 section 21, dated 3-June-92.)
57 * To avoid floating-point arithmetic, we represent the fractional constants
58 * as integers scaled up by 2^16 (about 4 digits precision); we have to divide
59 * the products by 2^16, with appropriate rounding, to get the correct answer.
60 * Notice that Y, being an integral input, does not contribute any fraction
61 * so it need not participate in the rounding.
63 * For even more speed, we avoid doing any multiplications in the inner loop
64 * by precalculating the constants times Cb and Cr for all possible values.
65 * For 8-bit JSAMPLEs this is very reasonable (only 256 entries per table);
66 * for 12-bit samples it is still acceptable. It's not very reasonable for
67 * 16-bit samples, but if you want lossless storage you shouldn't be changing
69 * The Cr=>R and Cb=>B values can be rounded to integers in advance; the
70 * values for the G calculation are left scaled up, since we must add them
71 * together before rounding.
74 #define SCALEBITS 16 /* speediest right-shift on some machines */
75 #define ONE_HALF ((INT32) 1 << (SCALEBITS-1))
76 #define FIX(x) ((INT32) ((x) * (1L<<SCALEBITS) + 0.5))
78 /* We allocate one big table for RGB->Y conversion and divide it up into
79 * three parts, instead of doing three alloc_small requests. This lets us
80 * use a single table base address, which can be held in a register in the
81 * inner loops on many machines (more than can hold all three addresses,
85 #define R_Y_OFF 0 /* offset to R => Y section */
86 #define G_Y_OFF (1*(MAXJSAMPLE+1)) /* offset to G => Y section */
87 #define B_Y_OFF (2*(MAXJSAMPLE+1)) /* etc. */
88 #define TABLE_SIZE (3*(MAXJSAMPLE+1))
91 /* Include inline routines for colorspace extensions */
99 #define RGB_RED EXT_RGB_RED
100 #define RGB_GREEN EXT_RGB_GREEN
101 #define RGB_BLUE EXT_RGB_BLUE
102 #define RGB_PIXELSIZE EXT_RGB_PIXELSIZE
103 #define ycc_rgb_convert_internal ycc_extrgb_convert_internal
104 #define gray_rgb_convert_internal gray_extrgb_convert_internal
105 #define rgb_rgb_convert_internal rgb_extrgb_convert_internal
106 #include "jdcolext.c"
111 #undef ycc_rgb_convert_internal
112 #undef gray_rgb_convert_internal
113 #undef rgb_rgb_convert_internal
115 #define RGB_RED EXT_RGBX_RED
116 #define RGB_GREEN EXT_RGBX_GREEN
117 #define RGB_BLUE EXT_RGBX_BLUE
119 #define RGB_PIXELSIZE EXT_RGBX_PIXELSIZE
120 #define ycc_rgb_convert_internal ycc_extrgbx_convert_internal
121 #define gray_rgb_convert_internal gray_extrgbx_convert_internal
122 #define rgb_rgb_convert_internal rgb_extrgbx_convert_internal
123 #include "jdcolext.c"
129 #undef ycc_rgb_convert_internal
130 #undef gray_rgb_convert_internal
131 #undef rgb_rgb_convert_internal
133 #define RGB_RED EXT_BGR_RED
134 #define RGB_GREEN EXT_BGR_GREEN
135 #define RGB_BLUE EXT_BGR_BLUE
136 #define RGB_PIXELSIZE EXT_BGR_PIXELSIZE
137 #define ycc_rgb_convert_internal ycc_extbgr_convert_internal
138 #define gray_rgb_convert_internal gray_extbgr_convert_internal
139 #define rgb_rgb_convert_internal rgb_extbgr_convert_internal
140 #include "jdcolext.c"
145 #undef ycc_rgb_convert_internal
146 #undef gray_rgb_convert_internal
147 #undef rgb_rgb_convert_internal
149 #define RGB_RED EXT_BGRX_RED
150 #define RGB_GREEN EXT_BGRX_GREEN
151 #define RGB_BLUE EXT_BGRX_BLUE
153 #define RGB_PIXELSIZE EXT_BGRX_PIXELSIZE
154 #define ycc_rgb_convert_internal ycc_extbgrx_convert_internal
155 #define gray_rgb_convert_internal gray_extbgrx_convert_internal
156 #define rgb_rgb_convert_internal rgb_extbgrx_convert_internal
157 #include "jdcolext.c"
163 #undef ycc_rgb_convert_internal
164 #undef gray_rgb_convert_internal
165 #undef rgb_rgb_convert_internal
167 #define RGB_RED EXT_XBGR_RED
168 #define RGB_GREEN EXT_XBGR_GREEN
169 #define RGB_BLUE EXT_XBGR_BLUE
171 #define RGB_PIXELSIZE EXT_XBGR_PIXELSIZE
172 #define ycc_rgb_convert_internal ycc_extxbgr_convert_internal
173 #define gray_rgb_convert_internal gray_extxbgr_convert_internal
174 #define rgb_rgb_convert_internal rgb_extxbgr_convert_internal
175 #include "jdcolext.c"
181 #undef ycc_rgb_convert_internal
182 #undef gray_rgb_convert_internal
183 #undef rgb_rgb_convert_internal
185 #define RGB_RED EXT_XRGB_RED
186 #define RGB_GREEN EXT_XRGB_GREEN
187 #define RGB_BLUE EXT_XRGB_BLUE
189 #define RGB_PIXELSIZE EXT_XRGB_PIXELSIZE
190 #define ycc_rgb_convert_internal ycc_extxrgb_convert_internal
191 #define gray_rgb_convert_internal gray_extxrgb_convert_internal
192 #define rgb_rgb_convert_internal rgb_extxrgb_convert_internal
193 #include "jdcolext.c"
199 #undef ycc_rgb_convert_internal
200 #undef gray_rgb_convert_internal
201 #undef rgb_rgb_convert_internal
205 * Initialize tables for YCC->RGB colorspace conversion.
209 build_ycc_rgb_table (j_decompress_ptr cinfo
)
211 my_cconvert_ptr cconvert
= (my_cconvert_ptr
) cinfo
->cconvert
;
216 cconvert
->Cr_r_tab
= (int *)
217 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
218 (MAXJSAMPLE
+1) * SIZEOF(int));
219 cconvert
->Cb_b_tab
= (int *)
220 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
221 (MAXJSAMPLE
+1) * SIZEOF(int));
222 cconvert
->Cr_g_tab
= (INT32
*)
223 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
224 (MAXJSAMPLE
+1) * SIZEOF(INT32
));
225 cconvert
->Cb_g_tab
= (INT32
*)
226 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
227 (MAXJSAMPLE
+1) * SIZEOF(INT32
));
229 for (i
= 0, x
= -CENTERJSAMPLE
; i
<= MAXJSAMPLE
; i
++, x
++) {
230 /* i is the actual input pixel value, in the range 0..MAXJSAMPLE */
231 /* The Cb or Cr value we are thinking of is x = i - CENTERJSAMPLE */
232 /* Cr=>R value is nearest int to 1.40200 * x */
233 cconvert
->Cr_r_tab
[i
] = (int)
234 RIGHT_SHIFT(FIX(1.40200) * x
+ ONE_HALF
, SCALEBITS
);
235 /* Cb=>B value is nearest int to 1.77200 * x */
236 cconvert
->Cb_b_tab
[i
] = (int)
237 RIGHT_SHIFT(FIX(1.77200) * x
+ ONE_HALF
, SCALEBITS
);
238 /* Cr=>G value is scaled-up -0.71414 * x */
239 cconvert
->Cr_g_tab
[i
] = (- FIX(0.71414)) * x
;
240 /* Cb=>G value is scaled-up -0.34414 * x */
241 /* We also add in ONE_HALF so that need not do it in inner loop */
242 cconvert
->Cb_g_tab
[i
] = (- FIX(0.34414)) * x
+ ONE_HALF
;
248 * Convert some rows of samples to the output colorspace.
252 ycc_rgb_convert (j_decompress_ptr cinfo
,
253 JSAMPIMAGE input_buf
, JDIMENSION input_row
,
254 JSAMPARRAY output_buf
, int num_rows
)
256 switch (cinfo
->out_color_space
) {
258 ycc_extrgb_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
263 ycc_extrgbx_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
267 ycc_extbgr_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
272 ycc_extbgrx_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
277 ycc_extxbgr_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
282 ycc_extxrgb_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
286 ycc_rgb_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
293 /**************** Cases other than YCbCr -> RGB **************/
297 * Initialize for RGB->grayscale colorspace conversion.
301 build_rgb_y_table (j_decompress_ptr cinfo
)
303 my_cconvert_ptr cconvert
= (my_cconvert_ptr
) cinfo
->cconvert
;
307 /* Allocate and fill in the conversion tables. */
308 cconvert
->rgb_y_tab
= rgb_y_tab
= (INT32
*)
309 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
310 (TABLE_SIZE
* SIZEOF(INT32
)));
312 for (i
= 0; i
<= MAXJSAMPLE
; i
++) {
313 rgb_y_tab
[i
+R_Y_OFF
] = FIX(0.29900) * i
;
314 rgb_y_tab
[i
+G_Y_OFF
] = FIX(0.58700) * i
;
315 rgb_y_tab
[i
+B_Y_OFF
] = FIX(0.11400) * i
+ ONE_HALF
;
321 * Convert RGB to grayscale.
325 rgb_gray_convert (j_decompress_ptr cinfo
,
326 JSAMPIMAGE input_buf
, JDIMENSION input_row
,
327 JSAMPARRAY output_buf
, int num_rows
)
329 my_cconvert_ptr cconvert
= (my_cconvert_ptr
) cinfo
->cconvert
;
330 register int r
, g
, b
;
331 register INT32
* ctab
= cconvert
->rgb_y_tab
;
332 register JSAMPROW outptr
;
333 register JSAMPROW inptr0
, inptr1
, inptr2
;
334 register JDIMENSION col
;
335 JDIMENSION num_cols
= cinfo
->output_width
;
337 while (--num_rows
>= 0) {
338 inptr0
= input_buf
[0][input_row
];
339 inptr1
= input_buf
[1][input_row
];
340 inptr2
= input_buf
[2][input_row
];
342 outptr
= *output_buf
++;
343 for (col
= 0; col
< num_cols
; col
++) {
344 r
= GETJSAMPLE(inptr0
[col
]);
345 g
= GETJSAMPLE(inptr1
[col
]);
346 b
= GETJSAMPLE(inptr2
[col
]);
348 outptr
[col
] = (JSAMPLE
)
349 ((ctab
[r
+R_Y_OFF
] + ctab
[g
+G_Y_OFF
] + ctab
[b
+B_Y_OFF
])
357 * Color conversion for no colorspace change: just copy the data,
358 * converting from separate-planes to interleaved representation.
362 null_convert (j_decompress_ptr cinfo
,
363 JSAMPIMAGE input_buf
, JDIMENSION input_row
,
364 JSAMPARRAY output_buf
, int num_rows
)
366 register JSAMPROW inptr
, outptr
;
367 register JDIMENSION count
;
368 register int num_components
= cinfo
->num_components
;
369 JDIMENSION num_cols
= cinfo
->output_width
;
372 while (--num_rows
>= 0) {
373 for (ci
= 0; ci
< num_components
; ci
++) {
374 inptr
= input_buf
[ci
][input_row
];
375 outptr
= output_buf
[0] + ci
;
376 for (count
= num_cols
; count
> 0; count
--) {
377 *outptr
= *inptr
++; /* needn't bother with GETJSAMPLE() here */
378 outptr
+= num_components
;
388 * Color conversion for grayscale: just copy the data.
389 * This also works for YCbCr -> grayscale conversion, in which
390 * we just copy the Y (luminance) component and ignore chrominance.
394 grayscale_convert (j_decompress_ptr cinfo
,
395 JSAMPIMAGE input_buf
, JDIMENSION input_row
,
396 JSAMPARRAY output_buf
, int num_rows
)
398 jcopy_sample_rows(input_buf
[0], (int) input_row
, output_buf
, 0,
399 num_rows
, cinfo
->output_width
);
404 * Convert grayscale to RGB
408 gray_rgb_convert (j_decompress_ptr cinfo
,
409 JSAMPIMAGE input_buf
, JDIMENSION input_row
,
410 JSAMPARRAY output_buf
, int num_rows
)
412 switch (cinfo
->out_color_space
) {
414 gray_extrgb_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
419 gray_extrgbx_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
423 gray_extbgr_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
428 gray_extbgrx_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
433 gray_extxbgr_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
438 gray_extxrgb_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
442 gray_rgb_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
450 * Convert plain RGB to extended RGB
454 rgb_rgb_convert (j_decompress_ptr cinfo
,
455 JSAMPIMAGE input_buf
, JDIMENSION input_row
,
456 JSAMPARRAY output_buf
, int num_rows
)
458 switch (cinfo
->out_color_space
) {
460 rgb_extrgb_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
465 rgb_extrgbx_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
469 rgb_extbgr_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
474 rgb_extbgrx_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
479 rgb_extxbgr_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
484 rgb_extxrgb_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
488 rgb_rgb_convert_internal(cinfo
, input_buf
, input_row
, output_buf
,
496 * Adobe-style YCCK->CMYK conversion.
497 * We convert YCbCr to R=1-C, G=1-M, and B=1-Y using the same
498 * conversion as above, while passing K (black) unchanged.
499 * We assume build_ycc_rgb_table has been called.
503 ycck_cmyk_convert (j_decompress_ptr cinfo
,
504 JSAMPIMAGE input_buf
, JDIMENSION input_row
,
505 JSAMPARRAY output_buf
, int num_rows
)
507 my_cconvert_ptr cconvert
= (my_cconvert_ptr
) cinfo
->cconvert
;
508 register int y
, cb
, cr
;
509 register JSAMPROW outptr
;
510 register JSAMPROW inptr0
, inptr1
, inptr2
, inptr3
;
511 register JDIMENSION col
;
512 JDIMENSION num_cols
= cinfo
->output_width
;
513 /* copy these pointers into registers if possible */
514 register JSAMPLE
* range_limit
= cinfo
->sample_range_limit
;
515 register int * Crrtab
= cconvert
->Cr_r_tab
;
516 register int * Cbbtab
= cconvert
->Cb_b_tab
;
517 register INT32
* Crgtab
= cconvert
->Cr_g_tab
;
518 register INT32
* Cbgtab
= cconvert
->Cb_g_tab
;
521 while (--num_rows
>= 0) {
522 inptr0
= input_buf
[0][input_row
];
523 inptr1
= input_buf
[1][input_row
];
524 inptr2
= input_buf
[2][input_row
];
525 inptr3
= input_buf
[3][input_row
];
527 outptr
= *output_buf
++;
528 for (col
= 0; col
< num_cols
; col
++) {
529 y
= GETJSAMPLE(inptr0
[col
]);
530 cb
= GETJSAMPLE(inptr1
[col
]);
531 cr
= GETJSAMPLE(inptr2
[col
]);
532 /* Range-limiting is essential due to noise introduced by DCT losses. */
533 outptr
[0] = range_limit
[MAXJSAMPLE
- (y
+ Crrtab
[cr
])]; /* red */
534 outptr
[1] = range_limit
[MAXJSAMPLE
- (y
+ /* green */
535 ((int) RIGHT_SHIFT(Cbgtab
[cb
] + Crgtab
[cr
],
537 outptr
[2] = range_limit
[MAXJSAMPLE
- (y
+ Cbbtab
[cb
])]; /* blue */
538 /* K passes through unchanged */
539 outptr
[3] = inptr3
[col
]; /* don't need GETJSAMPLE here */
547 * Empty method for start_pass.
551 start_pass_dcolor (j_decompress_ptr cinfo
)
558 * Module initialization routine for output colorspace conversion.
562 jinit_color_deconverter (j_decompress_ptr cinfo
)
564 my_cconvert_ptr cconvert
;
567 cconvert
= (my_cconvert_ptr
)
568 (*cinfo
->mem
->alloc_small
) ((j_common_ptr
) cinfo
, JPOOL_IMAGE
,
569 SIZEOF(my_color_deconverter
));
570 cinfo
->cconvert
= (struct jpeg_color_deconverter
*) cconvert
;
571 cconvert
->pub
.start_pass
= start_pass_dcolor
;
573 /* Make sure num_components agrees with jpeg_color_space */
574 switch (cinfo
->jpeg_color_space
) {
576 if (cinfo
->num_components
!= 1)
577 ERREXIT(cinfo
, JERR_BAD_J_COLORSPACE
);
582 if (cinfo
->num_components
!= 3)
583 ERREXIT(cinfo
, JERR_BAD_J_COLORSPACE
);
588 if (cinfo
->num_components
!= 4)
589 ERREXIT(cinfo
, JERR_BAD_J_COLORSPACE
);
592 default: /* JCS_UNKNOWN can be anything */
593 if (cinfo
->num_components
< 1)
594 ERREXIT(cinfo
, JERR_BAD_J_COLORSPACE
);
598 /* Set out_color_components and conversion method based on requested space.
599 * Also clear the component_needed flags for any unused components,
600 * so that earlier pipeline stages can avoid useless computation.
603 switch (cinfo
->out_color_space
) {
605 cinfo
->out_color_components
= 1;
606 if (cinfo
->jpeg_color_space
== JCS_GRAYSCALE
||
607 cinfo
->jpeg_color_space
== JCS_YCbCr
) {
608 cconvert
->pub
.color_convert
= grayscale_convert
;
609 /* For color->grayscale conversion, only the Y (0) component is needed */
610 for (ci
= 1; ci
< cinfo
->num_components
; ci
++)
611 cinfo
->comp_info
[ci
].component_needed
= FALSE
;
612 } else if (cinfo
->jpeg_color_space
== JCS_RGB
) {
613 cconvert
->pub
.color_convert
= rgb_gray_convert
;
614 build_rgb_y_table(cinfo
);
616 ERREXIT(cinfo
, JERR_CONVERSION_NOTIMPL
);
630 cinfo
->out_color_components
= rgb_pixelsize
[cinfo
->out_color_space
];
631 if (cinfo
->jpeg_color_space
== JCS_YCbCr
) {
632 if (jsimd_can_ycc_rgb())
633 cconvert
->pub
.color_convert
= jsimd_ycc_rgb_convert
;
635 cconvert
->pub
.color_convert
= ycc_rgb_convert
;
636 build_ycc_rgb_table(cinfo
);
638 } else if (cinfo
->jpeg_color_space
== JCS_GRAYSCALE
) {
639 cconvert
->pub
.color_convert
= gray_rgb_convert
;
640 } else if (cinfo
->jpeg_color_space
== JCS_RGB
) {
641 if (rgb_red
[cinfo
->out_color_space
] == 0 &&
642 rgb_green
[cinfo
->out_color_space
] == 1 &&
643 rgb_blue
[cinfo
->out_color_space
] == 2 &&
644 rgb_pixelsize
[cinfo
->out_color_space
] == 3)
645 cconvert
->pub
.color_convert
= null_convert
;
647 cconvert
->pub
.color_convert
= rgb_rgb_convert
;
649 ERREXIT(cinfo
, JERR_CONVERSION_NOTIMPL
);
653 cinfo
->out_color_components
= 4;
654 if (cinfo
->jpeg_color_space
== JCS_YCCK
) {
655 cconvert
->pub
.color_convert
= ycck_cmyk_convert
;
656 build_ycc_rgb_table(cinfo
);
657 } else if (cinfo
->jpeg_color_space
== JCS_CMYK
) {
658 cconvert
->pub
.color_convert
= null_convert
;
660 ERREXIT(cinfo
, JERR_CONVERSION_NOTIMPL
);
664 /* Permit null conversion to same output space */
665 if (cinfo
->out_color_space
== cinfo
->jpeg_color_space
) {
666 cinfo
->out_color_components
= cinfo
->num_components
;
667 cconvert
->pub
.color_convert
= null_convert
;
668 } else /* unsupported non-null conversion */
669 ERREXIT(cinfo
, JERR_CONVERSION_NOTIMPL
);
673 if (cinfo
->quantize_colors
)
674 cinfo
->output_components
= 1; /* single colormapped output component */
676 cinfo
->output_components
= cinfo
->out_color_components
;