to565.c revision 88b607994a148f4af5bffee163e39ce8296750c6 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <stdio.h>
18#include <stdlib.h>
19#include <unistd.h>
20#include <string.h>
21
22#define to565(r,g,b)                                            \
23    ((((r) >> 3) << 11) | (((g) >> 2) << 5) | ((b) >> 3))
24
25#define from565_r(x) ((((x) >> 11) & 0x1f) * 255 / 31)
26#define from565_g(x) ((((x) >> 5) & 0x3f) * 255 / 63)
27#define from565_b(x) (((x) & 0x1f) * 255 / 31)
28
29void to_565_raw(void)
30{
31    unsigned char in[3];
32    unsigned short out;
33
34    while(read(0, in, 3) == 3) {
35        out = to565(in[0],in[1],in[2]);
36        write(1, &out, 2);
37    }
38    return;
39}
40
41void to_565_raw_dither(int width)
42{
43    unsigned char in[3];
44    unsigned short out;
45    int i = 0;
46    int e;
47
48    int* error = malloc((width+2) * 3 * sizeof(int));
49    int* next_error = malloc((width+2) * 3 * sizeof(int));
50    memset(error, 0, (width+2) * 3 * sizeof(int));
51    memset(next_error, 0, (width+2) * 3 * sizeof(int));
52    error += 3;        // array goes from [-3..((width+1)*3+2)]
53    next_error += 3;
54
55    while(read(0, in, 3) == 3) {
56        int r = in[0] + error[i*3+0];
57        int rb = (r < 0) ? 0 : ((r > 255) ? 255 : r);
58
59        int g = in[1] + error[i*3+1];
60        int gb = (g < 0) ? 0 : ((g > 255) ? 255 : g);
61
62        int b = in[2] + error[i*3+2];
63        int bb = (b < 0) ? 0 : ((b > 255) ? 255 : b);
64
65        out = to565(rb, gb, bb);
66        write(1, &out, 2);
67
68#define apply_error(ch) {                                               \
69            next_error[(i-1)*3+ch] += e * 3 / 16;                       \
70            next_error[(i)*3+ch] += e * 5 / 16;                         \
71            next_error[(i+1)*3+ch] += e * 1 / 16;                       \
72            error[(i+1)*3+ch] += e - ((e*1/16) + (e*3/16) + (e*5/16));  \
73        }
74
75        e = r - from565_r(out);
76        apply_error(0);
77
78        e = g - from565_g(out);
79        apply_error(1);
80
81        e = b - from565_b(out);
82        apply_error(2);
83
84#undef apply_error
85
86        ++i;
87        if (i == width) {
88            // error <- next_error; next_error <- 0
89            int* temp = error; error = next_error; next_error = temp;
90            memset(next_error, 0, (width+1) * 3 * sizeof(int));
91            i = 0;
92        }
93    }
94
95    free(error-3);
96    free(next_error-3);
97
98    return;
99}
100
101void to_565_rle(void)
102{
103    unsigned char in[3];
104    unsigned short last, color, count;
105    unsigned total = 0;
106    count = 0;
107
108    while(read(0, in, 3) == 3) {
109        color = to565(in[0],in[1],in[2]);
110        if (count) {
111            if ((color == last) && (count != 65535)) {
112                count++;
113                continue;
114            } else {
115                write(1, &count, 2);
116                write(1, &last, 2);
117                total += count;
118            }
119        }
120        last = color;
121        count = 1;
122    }
123    if (count) {
124        write(1, &count, 2);
125        write(1, &last, 2);
126        total += count;
127    }
128    fprintf(stderr,"%d pixels\n",total);
129}
130
131int main(int argc, char **argv)
132{
133    if ((argc == 2) && (!strcmp(argv[1],"-rle"))) {
134        to_565_rle();
135    } else {
136        if (argc > 2 && (!strcmp(argv[1], "-w"))) {
137            to_565_raw_dither(atoi(argv[2]));
138        } else {
139            to_565_raw();
140        }
141    }
142    return 0;
143}
144