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 (C) 2009-2012, 2015, 2022, D. R. Commander.
8 * For conditions of distribution and use, see the accompanying README.ijg
11 * This file contains input colorspace conversion routines.
15 /* This file is included by jccolor.c */
19 * Convert some rows of samples to the JPEG colorspace.
21 * Note that we change from the application's interleaved-pixel format
22 * to our internal noninterleaved, one-plane-per-component format.
23 * The input buffer is therefore three times as wide as the output buffer.
25 * A starting row offset is provided only for the output buffer. The caller
26 * can easily adjust the passed input_buf value to accommodate any row
27 * offset required on that side.
32 rgb_ycc_convert_internal(j_compress_ptr cinfo
, JSAMPARRAY input_buf
,
33 JSAMPIMAGE output_buf
, JDIMENSION output_row
,
36 my_cconvert_ptr cconvert
= (my_cconvert_ptr
)cinfo
->cconvert
;
38 register JLONG
*ctab
= cconvert
->rgb_ycc_tab
;
39 register JSAMPROW inptr
;
40 register JSAMPROW outptr0
, outptr1
, outptr2
;
41 register JDIMENSION col
;
42 JDIMENSION num_cols
= cinfo
->image_width
;
44 while (--num_rows
>= 0) {
46 outptr0
= output_buf
[0][output_row
];
47 outptr1
= output_buf
[1][output_row
];
48 outptr2
= output_buf
[2][output_row
];
50 for (col
= 0; col
< num_cols
; col
++) {
51 r
= RANGE_LIMIT(inptr
[RGB_RED
]);
52 g
= RANGE_LIMIT(inptr
[RGB_GREEN
]);
53 b
= RANGE_LIMIT(inptr
[RGB_BLUE
]);
54 inptr
+= RGB_PIXELSIZE
;
55 /* If the inputs are 0..MAXJSAMPLE, the outputs of these equations
56 * must be too; we do not need an explicit range-limiting operation.
57 * Hence the value being shifted is never negative, and we don't
58 * need the general RIGHT_SHIFT macro.
61 outptr0
[col
] = (JSAMPLE
)((ctab
[r
+ R_Y_OFF
] + ctab
[g
+ G_Y_OFF
] +
62 ctab
[b
+ B_Y_OFF
]) >> SCALEBITS
);
64 outptr1
[col
] = (JSAMPLE
)((ctab
[r
+ R_CB_OFF
] + ctab
[g
+ G_CB_OFF
] +
65 ctab
[b
+ B_CB_OFF
]) >> SCALEBITS
);
67 outptr2
[col
] = (JSAMPLE
)((ctab
[r
+ R_CR_OFF
] + ctab
[g
+ G_CR_OFF
] +
68 ctab
[b
+ B_CR_OFF
]) >> SCALEBITS
);
74 /**************** Cases other than RGB -> YCbCr **************/
78 * Convert some rows of samples to the JPEG colorspace.
79 * This version handles RGB->grayscale conversion, which is the same
80 * as the RGB->Y portion of RGB->YCbCr.
81 * We assume rgb_ycc_start has been called (we only use the Y tables).
86 rgb_gray_convert_internal(j_compress_ptr cinfo
, JSAMPARRAY input_buf
,
87 JSAMPIMAGE output_buf
, JDIMENSION output_row
,
90 my_cconvert_ptr cconvert
= (my_cconvert_ptr
)cinfo
->cconvert
;
92 register JLONG
*ctab
= cconvert
->rgb_ycc_tab
;
93 register JSAMPROW inptr
;
94 register JSAMPROW outptr
;
95 register JDIMENSION col
;
96 JDIMENSION num_cols
= cinfo
->image_width
;
98 while (--num_rows
>= 0) {
100 outptr
= output_buf
[0][output_row
];
102 for (col
= 0; col
< num_cols
; col
++) {
103 r
= RANGE_LIMIT(inptr
[RGB_RED
]);
104 g
= RANGE_LIMIT(inptr
[RGB_GREEN
]);
105 b
= RANGE_LIMIT(inptr
[RGB_BLUE
]);
106 inptr
+= RGB_PIXELSIZE
;
108 outptr
[col
] = (JSAMPLE
)((ctab
[r
+ R_Y_OFF
] + ctab
[g
+ G_Y_OFF
] +
109 ctab
[b
+ B_Y_OFF
]) >> SCALEBITS
);
116 * Convert some rows of samples to the JPEG colorspace.
117 * This version handles extended RGB->plain RGB conversion
122 rgb_rgb_convert_internal(j_compress_ptr cinfo
, JSAMPARRAY input_buf
,
123 JSAMPIMAGE output_buf
, JDIMENSION output_row
,
126 register JSAMPROW inptr
;
127 register JSAMPROW outptr0
, outptr1
, outptr2
;
128 register JDIMENSION col
;
129 JDIMENSION num_cols
= cinfo
->image_width
;
131 while (--num_rows
>= 0) {
132 inptr
= *input_buf
++;
133 outptr0
= output_buf
[0][output_row
];
134 outptr1
= output_buf
[1][output_row
];
135 outptr2
= output_buf
[2][output_row
];
137 for (col
= 0; col
< num_cols
; col
++) {
138 outptr0
[col
] = inptr
[RGB_RED
];
139 outptr1
[col
] = inptr
[RGB_GREEN
];
140 outptr2
[col
] = inptr
[RGB_BLUE
];
141 inptr
+= RGB_PIXELSIZE
;