1 /*
2 * Small jpeg decoder library
3 *
4 * Copyright (c) 2006, Luc Saillard <luc@saillard.org>
5 * All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * - Redistributions of source code must retain the above copyright notice,
10 * this list of conditions and the following disclaimer.
11 *
12 * - Redistributions in binary form must reproduce the above copyright notice,
13 * this list of conditions and the following disclaimer in the documentation
14 * and/or other materials provided with the distribution.
15 *
16 * - Neither the name of the author nor the names of its contributors may be
17 * used to endorse or promote products derived from this software without
18 * specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 *
32 */
33
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <stdint.h>
38
39 #include "tinyjpeg.h"
40 #include "tinyjpeg-internal.h"
41
42 /**
43 * YCrCb -> Grey (1x1, 1x2)
44 * .---.
45 * | 1 |
46 * `---'
47 */
YCrCB_to_Grey_1xN(struct jdec_private * priv,int sx,int sy)48 static void YCrCB_to_Grey_1xN(struct jdec_private *priv, int sx, int sy)
49 {
50 const unsigned char *y;
51 unsigned char *p;
52 unsigned int i;
53 int offset_to_next_row;
54
55 p = priv->plane[0];
56 y = priv->Y;
57 offset_to_next_row = priv->bytes_per_row[0];
58
59 for (i = sy; i > 0; i--) {
60 memcpy(p, y, sx);
61 y += 8;
62 p += offset_to_next_row;
63 }
64 }
65
66 /**
67 * YCrCb -> Grey (2x1, 2x2)
68 * .-------.
69 * | 1 | 2 |
70 * `-------'
71 */
YCrCB_to_Grey_2xN(struct jdec_private * priv,int sx,int sy)72 static void YCrCB_to_Grey_2xN(struct jdec_private *priv, int sx, int sy)
73 {
74 const unsigned char *y;
75 unsigned char *p;
76 unsigned int i;
77 int offset_to_next_row;
78
79 p = priv->plane[0];
80 y = priv->Y;
81 offset_to_next_row = priv->bytes_per_row[0];
82
83 for (i = sy; i > 0; i--) {
84 memcpy(p, y, sx);
85 y += 16;
86 p += offset_to_next_row;
87 }
88 }
89
initialize_grey(struct jdec_private * priv,unsigned int * bytes_per_blocklines,unsigned int * bytes_per_mcu)90 static int initialize_grey(struct jdec_private *priv,
91 unsigned int *bytes_per_blocklines,
92 unsigned int *bytes_per_mcu)
93 {
94 if (!priv->bytes_per_row[0])
95 priv->bytes_per_row[0] = priv->width;
96 if (!priv->components[0])
97 priv->components[0] = malloc(priv->height * priv->bytes_per_row[0]);
98
99 bytes_per_blocklines[0] = priv->bytes_per_row[0] << 3;
100 bytes_per_mcu[0] = 8;
101
102 return !priv->components[0];
103 }
104
105 static const struct tinyjpeg_colorspace format_grey =
106 {
107 {
108 YCrCB_to_Grey_1xN,
109 YCrCB_to_Grey_1xN,
110 YCrCB_to_Grey_2xN,
111 YCrCB_to_Grey_2xN,
112 },
113 tinyjpeg_decode_mcu_1comp_table,
114 initialize_grey
115 };
116
117 const tinyjpeg_colorspace_t TINYJPEG_FMT_GREY = &format_grey;
118