5 #include "bytesource.h"
14 unsigned width, height;
15 unsigned num_components;
16 unsigned hsample[256], vsample[256], qtable[256];
17 unsigned max_hsample, max_vsample;
19 unsigned num_blocks_horizontal, num_blocks_vertical;
20 uint32_t qvalues[256][DCTSIZE2];
22 uint8_t* pixel_data[256];
23 uint8_t* pixel_write_pointer[256];
26 ssize_t stdio_read(void* userdata, uint8_t* buf, size_t count)
28 return fread(buf, 1, count, (FILE*)userdata);
31 void read_dqt(struct byte_source* source, struct jpeg_image* image)
33 unsigned len = read_uint16(byte_source_input_func, source);
35 uint8_t precision_table = read_uint8(byte_source_input_func, source);
36 int precision = precision_table >> 4; // 0 = 8 bits, otherwise 16 bits.
37 int table = precision_table & 0x0f;
39 if (image->idct_data[table] != NULL) {
40 idct_choice_free(image->idct_data[table]);
45 fprintf(stderr, "Quantization table %u: 16 bits/entry\n", table);
48 fprintf(stderr, "Quantization table %u: 8 bits/entry\n", table);
51 for (unsigned i = 0; i < 64; ++i) {
53 image->qvalues[table][unzigzag[i]] =
54 read_uint16(byte_source_input_func, source);
56 image->qvalues[table][unzigzag[i]] =
57 read_uint8(byte_source_input_func, source);
61 image->idct_data[table] = idct_choice_alloc(image->qvalues[table]);
64 void read_sof(struct byte_source* source, struct jpeg_image* image)
66 unsigned len = read_uint16(byte_source_input_func, source);
68 image->precision = read_uint8(byte_source_input_func, source);
69 assert(image->precision == 8);
70 image->height = read_uint16(byte_source_input_func, source);
71 image->width = read_uint16(byte_source_input_func, source);
72 image->num_components = read_uint8(byte_source_input_func, source);
75 fprintf(stderr, "%u-bit %ux%u JPEG with %u components\n",
76 image->precision, image->width, image->height, image->num_components);
78 for (unsigned i = 0; i < image->num_components; ++i) {
80 unsigned c = read_uint8(byte_source_input_func, source);
81 unsigned sampling_factors = read_uint8(byte_source_input_func, source);
82 image->hsample[c] = sampling_factors >> 4;
83 image->vsample[c] = sampling_factors & 0x0f;
84 image->qtable[c] = read_uint8(byte_source_input_func, source);
87 if (image->hsample[c] > image->max_hsample) {
88 image->max_hsample = image->hsample[c];
90 if (image->vsample[c] > image->max_vsample) {
91 image->max_vsample = image->vsample[c];
94 fprintf(stderr, "Component %u: sampling factors %u x %x, quantization table %u\n",
95 c, image->hsample[c], image->vsample[c], image->qtable[c]);
98 image->num_blocks_horizontal = (image->width + image->max_hsample * DCTSIZE - 1) / (image->max_hsample * DCTSIZE);
99 image->num_blocks_vertical = (image->height + image->max_vsample * DCTSIZE - 1) / (image->max_vsample * DCTSIZE);
101 for (unsigned c = 0; c < 256; ++c) {
102 if (image->hsample[c] == 0) {
106 unsigned width = image->num_blocks_horizontal * image->hsample[c] * DCTSIZE;
107 unsigned height = image->num_blocks_vertical * image->vsample[c] * DCTSIZE;
108 image->stride[c] = width;
109 image->pixel_data[c] = (uint8_t*)malloc(width * height);
110 assert(image->pixel_data[c] != NULL);
111 image->pixel_write_pointer[c] = image->pixel_data[c];
113 fprintf(stderr, "Component %u: allocating %d x %d\n", c, width, height);
117 void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tables_t* tables)
119 unsigned len = read_uint16(byte_source_input_func, source);
124 unsigned num_components = read_uint8(byte_source_input_func, source);
127 unsigned component_num[256];
128 unsigned dc_huffman_table[256], ac_huffman_table[256];
129 unsigned ss, se, ah_al;
132 for (unsigned i = 0; i < num_components; ++i) {
135 component_num[i] = read_uint8(byte_source_input_func, source);
136 td_ta = read_uint8(byte_source_input_func, source);
138 dc_huffman_table[i] = td_ta >> 4;
139 ac_huffman_table[i] = td_ta & 0x0f;
144 ss = read_uint8(byte_source_input_func, source);
145 se = read_uint8(byte_source_input_func, source);
146 ah_al = read_uint8(byte_source_input_func, source);
150 fprintf(stderr, "Error: %u unused bytes at end of SOS segment\n", len);
153 struct bit_source bits;
154 init_bit_source(&bits, byte_source_input_func, 8, source);
156 unsigned mcu_x = 0, mcu_y = 0;
158 while (!bits.source_eof) {
159 for (unsigned c = 0; c < num_components; ++c) {
160 unsigned cn = component_num[c];
161 assert(image->idct_data[image->qtable[cn]] != NULL);
163 uint8_t* pixel_write_pointer_y = image->pixel_write_pointer[cn];
164 for (unsigned local_yb = 0; local_yb < image->vsample[cn]; ++local_yb, pixel_write_pointer_y += image->stride[cn] * DCTSIZE) {
165 uint8_t* pixel_write_pointer = pixel_write_pointer_y;
166 for (unsigned local_xb = 0; local_xb < image->hsample[cn]; ++local_xb, pixel_write_pointer += DCTSIZE) {
167 const struct huffman_table* dc_table = &((*tables)[DC_CLASS][dc_huffman_table[c]]);
168 const struct huffman_table* ac_table = &((*tables)[AC_CLASS][ac_huffman_table[c]]);
170 // decode DC component
171 unsigned dc_category = read_huffman_symbol(dc_table, &bits);
172 possibly_refill(&bits, dc_category + DEHUF_TABLE_BITS);
173 last_dc[c] += extend(read_bits(&bits, dc_category), dc_category);
175 int16_t coeff[DCTSIZE2] = { 0 };
176 coeff[0] = last_dc[c];
178 // decode AC components
179 for (unsigned i = 1; i < DCTSIZE2; ++i) {
180 unsigned rs = read_huffman_symbol_no_refill(ac_table, &bits);
181 unsigned r = rs >> 4;
182 unsigned s = rs & 0xf;
190 /* 16 zero coefficients */
191 possibly_refill(&bits, DEHUF_TABLE_BITS);
195 possibly_refill(&bits, s + DEHUF_TABLE_BITS);
196 coeff[unzigzag[i]] = extend(read_bits(&bits, s), s);
199 uint8_t pixdata[DCTSIZE2];
200 idct_choice(coeff, image->idct_data[image->qtable[cn]], pixdata);
202 uint8_t* dest_pixdata = pixel_write_pointer;
203 for (unsigned y = 0; y < DCTSIZE; ++y, dest_pixdata += image->stride[cn]) {
204 memcpy(dest_pixdata, pixdata + y * DCTSIZE, DCTSIZE);
208 image->pixel_write_pointer[cn] += DCTSIZE * image->hsample[cn];
211 if (++mcu_x == image->num_blocks_horizontal) {
215 for (unsigned c = 0; c < num_components; ++c) {
216 unsigned cn = component_num[c];
217 image->pixel_write_pointer[cn] += (image->vsample[cn] * DCTSIZE - 1) * image->stride[cn];
222 if (mcu_y == image->num_blocks_vertical) {
223 unsigned stride = image->num_blocks_horizontal * image->hsample[c] * DCTSIZE;
224 unsigned height = image->num_blocks_vertical * image->vsample[c] * DCTSIZE;
225 printf("P5\n%u %u\n255\n", stride, height);
226 fwrite(image->pixel_data[c], stride * height, 1, stdout);
231 fprintf(stderr, "Error: %u unused bytes at end of SOS segment\n", len);
235 void skip_segment(struct byte_source* source)
239 ssize_t ret = byte_source_input_func(source, buf, 4096);
241 fprintf(stderr, "Input error!\n");
252 struct jpeg_image jpeg;
253 memset(&jpeg, 0, sizeof(jpeg));
256 struct byte_source source;
257 init_byte_source(&source, stdio_read, stdin);
259 huffman_tables_t tables;
262 uint8_t m2 = byte_source_read_marker(&source);
265 fprintf(stderr, "Marker 0x%02x, at position %ld\n", m2, ftell(stdin) - source.bytes_available);
284 /* APP0 through APPF */
286 /* some EXIF stuff */
291 skip_segment(&source);
295 read_dqt(&source, &jpeg);
298 /* SOF0 (baseline DCT, Huffman encoded) */
299 read_sof(&source, &jpeg);
308 /* DHT (define Huffman tables) */
309 read_huffman_tables(&tables, byte_source_input_func, &source);
312 /* SOS (start of scan) */
313 read_scan(&source, &jpeg, &tables);
316 fprintf(stderr, "Error: Unknown marker 0x%02x\n", m2);