本篇文章首先介绍了bmp图片格式，主要参考wiki上的内容，包括bmp文件的存储方式，对于一些常见的bmp文件格式都给了例子，并且对8位 16位RGB555 16位RGB565格式的bmp文件进行了简单分析，最后的代码可以将8位，16位，24位，32位色彩深度的bmp文件转化位8位灰度图片，用作后续文章中算法的测试图片。
Bmp file structure
Bitmap file header
DIB header （bitmap information header）
compression method
将bmp文件转换为8位灰度图片
1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <string.h> 4 #include <math.h> 5 6 #define GRAY_LEVELS 255 7 8 struct bmpfileheader{ 9 unsigned short filetype; 10 unsigned long filesize; 11 short reserved1; 12 short reserved2; 13 unsigned long bitmapoffset; 14 }; 15 16 struct bitmapheader{ 17 unsigned long size; 18 long width; 19 long height; 20 unsigned short planes; 21 unsigned short bitsperpixel; 22 unsigned long compression; 23 unsigned long sizeofbitmap; 24 unsigned long horzres; 25 unsigned long vertres; 26 unsigned long colorsused; 27 unsigned long colorsimp; 28 }; 29 30 struct ctstruct{ 31 unsigned char blue; 32 unsigned char green; 33 unsigned char red; 34 }; 35 36 union colortable_union{ 37 struct colortable 38 { 39 unsigned char blue; 40 unsigned char green; 41 unsigned char red; 42 unsigned char reserved; 43 }colortable; 44 unsigned long l_num; 45 }; 46 47 union short_char_union{ 48 short s_num; 49 char s_alpha[2]; 50 }; 51 52 union int_char_union{ 53 int i_num; 54 char i_alpha[2]; 55 }; 56 57 union long_char_union{ 58 long l_num; 59 char l_alpha[4]; 60 }; 61 62 union float_char_union{ 63 float f_num; 64 char f_alpha[4]; 65 }; 66 67 union ushort_char_union{ 68 short s_num; 69 char s_alpha[2]; 70 }; 71 72 union uint_char_union{ 73 int i_num; 74 char i_alpha[2]; 75 }; 76 77 union ulong_char_union{ 78 long l_num; 79 char l_alpha[4]; 80 }; 81 82 union rgb565_union{ 83 struct rgb565_struct 84 { 85 unsigned red : 5; 86 unsigned green : 6; 87 unsigned blue : 5; 88 }rgb565_struct; 89 // short pixel; 90 char exchange[2]; 91 }; 92 93 union rgb555_union{ 94 struct rgb555_struct 95 { 96 unsigned red : 5; 97 unsigned green : 5; 98 unsigned blue : 5; 99 unsigned reserved : 1; 100 }rgb555_struct; 101 // short pixel; 102 char exchange[2]; 103 }; 104 105 union bpp24_union{ 106 struct bpp24_struct 107 { 108 unsigned red : 8; 109 unsigned green : 8; 110 unsigned blue : 8; 111 }bpp24_struct; 112 char exchange[3]; 113 }; 114 115 union bpp32_union{ 116 struct bpp32_struct 117 { 118 unsigned red : 8; 119 unsigned green : 8; 120 unsigned blue : 8; 121 unsigned reserved : 8; 122 }bpp32_struct; 123 char exchange[4]; 124 }; 125 126 int get_image_size(const char* file_name, long* rows, long* cols); 127 void extract_long_from_buffer(char buffer[], int lsb, int start, long* number); 128 void extract_ulong_from_buffer(char buffer[], int lsb, int start,unsigned long* number); 129 void extract_short_from_buffer(char buffer[], int lsb, int start, short* number); 130 void extract_ushort_from_buffer(char buffer[], int lsb, int start, unsigned short* number); 131 void insert_short_into_buffer(char buffer[], int start, short number); 132 void insert_ushort_into_buffer(char buffer[], int start, unsigned short number); 133 void insert_long_into_buffer(char buffer[], int start, long number); 134 void insert_ulong_into_buffer(char buffer[], int start, unsigned long number); 135 short **allocate_image_array(long length, long width); 136 int free_image_array(short **the_array, long length); 137 void create_allocate_bmp_file(const char* file_name, struct bmpfileheader* file_header, struct bitmapheader* bmheader); 138 void read_bmp_file_header(const char* file_name, struct bmpfileheader* file_header); 139 void read_bm_header(const char* file_name, struct bitmapheader* bmheader); 140 int calculate_pad(long width); 141 void write_bmp_image(const char* file_name, short **array); 142 int does_not_exist(const char* file_name); 143 union colortable_union* read_allocate_colortable(const char* file_name, struct bitmapheader* bmheader); 144 void free_colortable(union colortable_union* colortable); 145 void bpp82grayscale(long height, long width, FILE* fp, short** the_image, int pad, 146 const char* file_name, struct bitmapheader* bmheader); 147 void rgb5552grayscale(long height, long width, FILE* fp, short** the_image, int pad); 148 void rgb5652grayscale(long height, long width, FILE* fp, short** the_image, int pad); 149 void bpp242grayscale(long height, long width, FILE* fp, short** the_image, int pad); 150 void bpp322grayscale(long height, long width, FILE* fp, short** the_image, int pad); 151 void rgb2grayscale_array(const char* file_name, short** the_image); 152 void flip_image_array(short** the_image, long rows, long cols); 157 158 int main(int argc, char const *argv[]) 159 { 160 char* cc; 161 long l, w; 162 short** grayscale_array; 163 struct bmpfileheader bmp_file_header; 164 struct bitmapheader bmheader; 165 166 if(argc < 3){ 167 printf("\nusage: rgb5652bmp rgb565-file-name grayscale-file-name\n"); 168 exit(-1); 169 } 170 if(does_not_exist(argv[1])){ 171 printf("\nERROR input file %s does not exist", argv[1]); 172 exit(0); 173 } 174 cc = strstr(argv[1], ".bmp"); 175 if(cc == NULL){ 176 printf("\nERROR %s must be a bmp file", argv[1]); 177 exit(0); 178 } 179 cc = strstr(argv[2], ".bmp"); 180 if(cc == NULL){ /* create a bmp */ 181 printf("\nERROR %s must be a bmp file name", argv[2]); 182 exit(0); 183 } 184 185 get_image_size(argv[1], &l, &w); 186 grayscale_array = allocate_image_array(l, w); 187 bmheader.height = l; 188 bmheader.width = w; 189 190 create_allocate_bmp_file(argv[2], &bmp_file_header, &bmheader); // create grayscale image file 191 192 rgb2grayscale_array(argv[1], grayscale_array); 193 write_bmp_image(argv[2], grayscale_array); 194 195 free_image_array(grayscale_array, l); 196 197 return 0; 198 } 199 200 void rgb2grayscale_array(const char* file_name, short** the_image) 201 { 202 FILE* fp; 203 int negative = 0, 204 pad = 0; 205 long height = 0, 206 width = 0; 207 struct bmpfileheader file_header; 208 struct bitmapheader bmheader; 211 212 read_bmp_file_header(file_name, &file_header); 213 read_bm_header(file_name, &bmheader); 214 215 fp = fopen(file_name, "rb"); 216 fseek(fp, file_header.bitmapoffset, SEEK_SET); 217 218 width = bmheader.width; 219 if(bmheader.height < 0){ 220 height = bmheader.height * (-1); 221 negative = 1; 222 } 223 else 224 height = bmheader.height; 225 226 pad = calculate_pad(width); 227 228 if (bmheader.bitsperpixel == 16 && bmheader.compression == 0x03) 229 rgb5652grayscale(height, width, fp, the_image, pad); 230 else if (bmheader.bitsperpixel == 16 && bmheader.compression == 0x00) 231 rgb5552grayscale(height, width, fp, the_image, pad); 232 else if (bmheader.bitsperpixel == 24 && bmheader.compression == 0x00) 233 bpp242grayscale(height, width, fp, the_image, pad); 234 else if (bmheader.bitsperpixel == 32 && bmheader.compression == 0x00) 235 bpp322grayscale(height, width, fp, the_image, pad); 236 else if (bmheader.bitsperpixel == 8) 237 bpp82grayscale(height, width, fp, the_image, pad, file_name, &bmheader); 238 else 239 { 240 printf("Unknow image format\n"); 241 exit(0); 242 } 243 244 if(negative == 0) 245 flip_image_array(the_image, height, width); 246 } 247 248 void bpp82grayscale(long height, long width, FILE* fp, short** the_image, int pad, 249 const char* file_name, struct bitmapheader* bmheader) 250 { 251 union colortable_union* colortable = NULL; 252 unsigned char pixel_index; 253 254 colortable = read_allocate_colortable(file_name, bmheader); 255 for(int i=0; i<height; i++){ 256 for(int j=0; j<width; j++){ 257 fread(&pixel_index, 1, 1, fp); 258 // printf("%u\n", pixel_index); 259 the_image[i][j] = ((colortable[pixel_index].colortable.red) + 260 (colortable[pixel_index].colortable.blue) + 261 (colortable[pixel_index].colortable.green)) / 3; 262 } /* ends loop over j */ 263 if(pad != 0){ 264 fseek(fp, pad, SEEK_CUR); 265 } /* ends if pad 1= 0 */ 266 } /* ends loop over i */ 267 free_colortable(colortable); 268 } 269 270 union colortable_union* read_allocate_colortable(const char* file_name, struct bitmapheader* bmheader) 271 { 272 union colortable_union* colortable = NULL; 273 char buffer[10]; 274 unsigned long ull; 275 FILE *fp; 276 long table_size = (long)pow(2, bmheader->bitsperpixel); 277 278 fp = fopen(file_name, "rb"); 279 colortable = malloc(sizeof(union colortable_union) * table_size); 280 281 fseek(fp, 54, SEEK_SET); 282 283 for (int i = 0; i < table_size; i++) 284 { 285 fread(buffer, 1, 4, fp); 286 extract_ulong_from_buffer(buffer, 1, 1, &ull); 287 colortable[i].l_num = ull; 288 } 289 290 fclose(fp); 291 return colortable; 292 } 293 294 void free_colortable(union colortable_union* colortable) 295 { 296 free(colortable); 297 } 298 299 void rgb5652grayscale(long height, long width, FILE* fp, short** the_image, int pad) 300 { 301 union rgb565_union pixel; 302 303 for(int i=0; i<height; i++){ 304 for(int j=0; j<width; j++){ 305 fread(&pixel, 1, 2, fp); 306 307 the_image[i][j] = ((pixel.rgb565_struct.red<<3) + 308 (pixel.rgb565_struct.green<<2) + 309 (pixel.rgb565_struct.blue<<3)) / 3; 310 } /* ends loop over j */ 311 if(pad != 0){ 312 fseek(fp, pad, SEEK_CUR); 313 } /* ends if pad 1= 0 */ 314 } /* ends loop over i */ 315 } 316 317 void rgb5552grayscale(long height, long width, FILE* fp, short** the_image, int pad) 318 { 319 union rgb555_union pixel; 320 321 for(int i=0; i<height; i++){ 322 for(int j=0; j<width; j++){ 323 fread(&pixel, 1, 2, fp); 324 the_image[i][j] = ((pixel.rgb555_struct.red<<3) + 325 (pixel.rgb555_struct.green<<3) + 326 (pixel.rgb555_struct.blue<<3)) / 3; 327 } /* ends loop over j */ 328 if(pad != 0){ 329 fseek(fp, pad, SEEK_CUR); 330 } /* ends if pad 1= 0 */ 331 } /* ends loop over i */ 332 } 333 334 void bpp242grayscale(long height, long width, FILE* fp, short** the_image, int pad) 335 { 336 union bpp24_union pixel; 337 338 for(int i=0; i<height; i++){ 339 for(int j=0; j<width; j++){ 340 fread(&pixel, 1, 3, fp); 341 the_image[i][j] = ((pixel.bpp24_struct.red) + 342 (pixel.bpp24_struct.green) + 343 (pixel.bpp24_struct.blue)) / 3; 344 } /* ends loop over j */ 345 if(pad != 0){ 346 fseek(fp, pad, SEEK_CUR); 347 } /* ends if pad 1= 0 */ 348 } /* ends loop over i */ 349 } 350 351 void bpp322grayscale(long height, long width, FILE* fp, short** the_image, int pad) 352 { 353 union bpp32_union pixel; 354 355 for(int i=0; i<height; i++){ 356 for(int j=0; j<width; j++){ 357 fread(&pixel, 1, 4, fp); 358 the_image[i][j] = ((pixel.bpp32_struct.red) + 359 (pixel.bpp32_struct.green) + 360 (pixel.bpp32_struct.blue)) / 3; 361 } /* ends loop over j */ 362 if(pad != 0){ 363 fseek(fp, pad, SEEK_CUR); 364 } /* ends if pad 1= 0 */ 365 } /* ends loop over i */ 366 } 367 368 void flip_image_array(short** the_image, long rows, long cols) 369 { 370 int i, j; 371 long rd2; 372 short **temp; 373 374 temp = allocate_image_array(rows, cols); 375 rd2 = rows/2; 376 for(i=0; i<rd2; i++){ 377 for(j=0; j<cols; j++){ 378 temp[rows-1-i][j] = the_image[i][j]; 379 } /* ends loop over j */ 380 } /* ends loop over i */ 381 382 for(i=rd2; i<rows; i++){ 383 for(j=0; j<cols; j++){ 384 temp[rows-1-i][j] = the_image[i][j]; 385 } /* ends loop over j */ 386 } /* ends loop over i */ 387 388 for(i=0; i<rows; i++) 389 for(j=0; j<cols; j++) 390 the_image[i][j] = temp[i][j]; 391 392 free_image_array(temp, rows); 393 } /* ends flip_image_array */ 394 395 int get_image_size(const char* file_name, long* rows, long* cols) 396 { 397 struct bitmapheader bmph; 398 399 read_bm_header(file_name, &bmph); 400 *rows = bmph.height; 401 *cols = bmph.width; 402 403 return 1; 404 } /* ends get_image_size */ 405 406 short **allocate_image_array(long length, long width) 407 { 408 int i; 409 short **the_array; 410 411 the_array = malloc(length * sizeof(short *)); 412 for(i=0; i<length; i++){ 413 the_array[i] = malloc(width * sizeof(short )); 414 if(the_array[i] == '\0'){ 415 printf("\n\tmalloc of the_image[%d] failed", i); 416 } /* ends if */ 417 } /* ends loop over i */ 418 return(the_array); 419 } /* ends allocate_image_array */ 420 421 int free_image_array(short **the_array, long length) 422 { 423 int i; 424 for(i=0; i<length; i++) 425 free(the_array[i]); 426 return(1); 427 } /* ends free_image_array */ 428 429 int calculate_pad(long width) 430 { 431 int pad = 0; 432 pad = ( (width%4) == 0) ? 0 : (4-(width%4)); 433 return(pad); 434 } /* ends calculate_pad */ 435 436 void create_allocate_bmp_file(const char *file_name, struct bmpfileheader *file_header, struct bitmapheader *bmheader) 437 { 438 char buffer[100]; 439 int i, pad = 0; 440 FILE *fp; 441 442 pad = calculate_pad(bmheader->width); 443 444 bmheader->size = 40; 445 bmheader->planes = 1; 446 bmheader->bitsperpixel = 8; 447 bmheader->compression = 0; 448 bmheader->sizeofbitmap = bmheader->height * 449 (bmheader->width + pad); 450 bmheader->horzres = 300; 451 bmheader->vertres = 300; 452 bmheader->colorsused = 256; 453 bmheader->colorsimp = 256; 454 455 file_header->filetype = 0x4D42; 456 file_header->reserved1 = 0; 457 file_header->reserved2 = 0; 458 file_header->bitmapoffset = 14 + 459 bmheader->size + 460 bmheader->colorsused*4; 461 file_header->filesize = file_header->bitmapoffset + 462 bmheader->sizeofbitmap; 463 464 if((fp = fopen(file_name, "wb")) == NULL){ 465 printf("\nERROR Could not create file %s", 466 file_name); 467 exit(2); 468 } 469 470 insert_ushort_into_buffer(buffer, 0, file_header->filetype); 471 fwrite(buffer, 1, 2, fp); 472 473 insert_ulong_into_buffer(buffer, 0, file_header->filesize); 474 fwrite(buffer, 1, 4, fp); 475 476 insert_short_into_buffer(buffer, 0, file_header->reserved1); 477 fwrite(buffer, 1, 2, fp); 478 479 insert_short_into_buffer(buffer, 0, file_header->reserved2); 480 fwrite(buffer, 1, 2, fp); 481 482 insert_ulong_into_buffer(buffer, 0, file_header->bitmapoffset); 483 fwrite(buffer, 1, 4, fp); 484 485 486 /********************************************* 487 * 488 * Write the 40-byte bit map header. 489 * 490 *********************************************/ 491 492 insert_ulong_into_buffer(buffer, 0, bmheader->size); 493 fwrite(buffer, 1, 4, fp); 494 495 insert_long_into_buffer(buffer, 0, bmheader->width); 496 fwrite(buffer, 1, 4, fp); 497 498 insert_long_into_buffer(buffer, 0, bmheader->height); 499 fwrite(buffer, 1, 4, fp); 500 501 insert_ushort_into_buffer(buffer, 0, bmheader->planes); 502 fwrite(buffer, 1, 2, fp); 503 504 insert_ushort_into_buffer(buffer, 0, bmheader->bitsperpixel); 505 fwrite(buffer, 1, 2, fp); 506 507 insert_ulong_into_buffer(buffer, 0, bmheader->compression); 508 fwrite(buffer, 1, 4, fp); 509 510 insert_ulong_into_buffer(buffer, 0, bmheader->sizeofbitmap); 511 fwrite(buffer, 1, 4, fp); 512 513 insert_ulong_into_buffer(buffer, 0, bmheader->horzres); 514 fwrite(buffer, 1, 4, fp); 515 516 insert_ulong_into_buffer(buffer, 0, bmheader->vertres); 517 fwrite(buffer, 1, 4, fp); 518 519 insert_ulong_into_buffer(buffer, 0, bmheader->colorsused); 520 fwrite(buffer, 1, 4, fp); 521 522 insert_ulong_into_buffer(buffer, 0, bmheader->colorsimp); 523 fwrite(buffer, 1, 4, fp); 524 525 /********************************************* 526 * 527 * Write a blank color table. 528 * It has 256 entries (number of colors) 529 * that are each 4 bytes. 530 * 531 *********************************************/ 532 533 buffer[0] = 0x00; 534 535 for(i=0; i<(256*4); i++) 536 fwrite(buffer, 1, 1, fp); 537 538 /********************************************* 539 * 540 * Write a zero image. 541 * 542 *********************************************/ 543 544 buffer[0] = 0x00; 545 546 for(i=0; i<bmheader->sizeofbitmap; i++) 547 fwrite(buffer, 1, 1, fp); 548 549 fclose(fp); 550 } /* ends create_allocate_bmp_file */ 551 552 void write_bmp_image(const char* file_name, short **array) 553 { 554 char *buffer; 555 FILE *image_file; 556 int pad = 0; 557 int i, j; 558 long height = 0, width = 0; 559 struct bitmapheader bmheader; 560 struct bmpfileheader file_header; 561 struct ctstruct rgb[GRAY_LEVELS+1]; 562 union short_char_union scu; 563 564 read_bmp_file_header(file_name, &file_header); 565 read_bm_header(file_name, &bmheader); 566 567 height = bmheader.height; 568 width = bmheader.width; 569 if(height < 0) 570 height = height*(-1); 571 572 buffer = (char *) malloc(width * sizeof(char )); 573 for(i=0; i<width; i++) 574 buffer[i] = '\0'; 575 576 image_file = fopen(file_name, "rb+"); 577 578 /**************************************** 579 * 580 * Write the color table first. 581 * 582 ****************************************/ 583 584 fseek(image_file, 54, SEEK_SET); 585 for(i=0; i<GRAY_LEVELS+1; i++){ 586 rgb[i].blue = i; 587 rgb[i].green = i; 588 rgb[i].red = i; 589 } /* ends loop over i */ 590 591 for(i=0; i<bmheader.colorsused; i++){ 592 buffer[0] = rgb[i].blue; 593 fwrite(buffer , 1, 1, image_file); 594 buffer[0] = rgb[i].green; 595 fwrite(buffer , 1, 1, image_file); 596 buffer[0] = rgb[i].red; 597 fwrite(buffer , 1, 1, image_file); 598 buffer[0] = 0x00; 599 fwrite(buffer , 1, 1, image_file); 600 } /* ends loop over i */ 601 602 fseek(image_file, file_header.bitmapoffset, SEEK_SET); 603 604 pad = calculate_pad(width); 605 606 for(i=0; i<height; i++){ 607 for(j=0; j<width; j++){ 608 609 if(bmheader.bitsperpixel == 8){ 610 scu.s_num = 0; 611 if(bmheader.height > 0) 612 scu.s_num = array[height-1-i][j]; 613 else 614 scu.s_num = array[i][j]; 615 buffer[j] = scu.s_alpha[0]; 616 } /* ends if bits_per_pixel == 8 */ 617 else{ 618 printf("\nERROR bitsperpixel is not 8"); 619 exit(1); 620 } 621 } /* ends loop over j */ 622 623 fwrite(buffer, 1, width, image_file); 624 625 if(pad != 0){ 626 for(j=0; j<pad; j++) 627 buffer[j] = 0x00; 628 fwrite(buffer, 1, pad, image_file); 629 } /* ends if pad != 0 */ 630 631 } /* ends loop over i */ 632 633 fclose(image_file); 634 free(buffer); 635 } /* ends write_bmp_image */ 636 637 void read_bmp_file_header(const char *file_name, struct bmpfileheader *file_header) 638 { 639 char buffer[10]; 640 short ss; 641 unsigned long ull; 642 unsigned short uss; 643 FILE *fp; 644 645 fp = fopen(file_name, "rb"); 646 647 fread(buffer, 1, 2, fp); 648 extract_ushort_from_buffer(buffer, 1, 0, &uss); 649 file_header->filetype = uss; 650 651 fread(buffer, 1, 4, fp); 652 extract_ulong_from_buffer(buffer, 1, 0, &ull); 653 file_header->filesize = ull; 654 655 fread(buffer, 1, 2, fp); 656 extract_short_from_buffer(buffer, 1, 0, &ss); 657 file_header->reserved1 = ss; 658 659 fread(buffer, 1, 2, fp); 660 extract_short_from_buffer(buffer, 1, 0, &ss); 661 file_header->reserved2 = ss; 662 663 fread(buffer, 1, 4, fp); 664 extract_ulong_from_buffer(buffer, 1, 0, &ull); 665 file_header->bitmapoffset = ull; 666 667 fclose(fp); 668 669 } /* ends read_bmp_file_header */ 670 671 void read_bm_header(const char* file_name, struct bitmapheader *bmheader) 672 { 673 char buffer[10]; 674 long ll; 675 unsigned long ull; 676 unsigned short uss; 677 FILE *fp; 678 679 fp = fopen(file_name, "rb"); 680 681 /**************************************** 682 * 683 * Seek past the first 14 byte header. 684 * 685 ****************************************/ 686 687 fseek(fp, 14, SEEK_SET); 688 689 fread(buffer, 1, 4, fp); 690 extract_ulong_from_buffer(buffer, 1, 0, &ull); 691 bmheader->size = ull; 692 693 fread(buffer, 1, 4, fp); 694 extract_long_from_buffer(buffer, 1, 0, &ll); 695 bmheader->width = ll; 696 697 fread(buffer, 1, 4, fp); 698 extract_long_from_buffer(buffer, 1, 0, &ll); 699 bmheader->height = ll; 700 701 fread(buffer, 1, 2, fp); 702 extract_ushort_from_buffer(buffer, 1, 0, &uss); 703 bmheader->planes = uss; 704 705 fread(buffer, 1, 2, fp); 706 extract_ushort_from_buffer(buffer, 1, 0, &uss); 707 bmheader->bitsperpixel = uss; 708 709 fread(buffer, 1, 4, fp); 710 extract_ulong_from_buffer(buffer, 1, 0, &ull); 711 bmheader->compression = ull; 712 713 fread(buffer, 1, 4, fp); 714 extract_ulong_from_buffer(buffer, 1, 0, &ull); 715 bmheader->sizeofbitmap = ull; 716 717 fread(buffer, 1, 4, fp); 718 extract_ulong_from_buffer(buffer, 1, 0, &ull); 719 bmheader->horzres = ull; 720 721 fread(buffer, 1, 4, fp); 722 extract_ulong_from_buffer(buffer, 1, 0, &ull); 723 bmheader->vertres = ull; 724 725 fread(buffer, 1, 4, fp); 726 extract_ulong_from_buffer(buffer, 1, 0, &ull); 727 bmheader->colorsused = ull; 728 729 fread(buffer, 1, 4, fp); 730 extract_ulong_from_buffer(buffer, 1, 0, &ull); 731 bmheader->colorsimp = ull; 732 733 fclose(fp); 734 } /* ends read_bm_header */ 735 736 void extract_long_from_buffer(char buffer[], int lsb, int start, long* number) 737 { 738 union long_char_union lcu; 739 740 if(lsb == 1){ 741 lcu.l_alpha[0] = buffer[start+0]; 742 lcu.l_alpha[1] = buffer[start+1]; 743 lcu.l_alpha[2] = buffer[start+2]; 744 lcu.l_alpha[3] = buffer[start+3]; 745 } /* ends if lsb = 1 */ 746 747 if(lsb == 0){ 748 lcu.l_alpha[0] = buffer[start+3]; 749 lcu.l_alpha[1] = buffer[start+2]; 750 lcu.l_alpha[2] = buffer[start+1]; 751 lcu.l_alpha[3] = buffer[start+0]; 752 } /* ends if lsb = 0 */ 753 754 *number = lcu.l_num; 755 } /* ends extract_long_from_buffer */ 756 757 void extract_ulong_from_buffer(char buffer[], int lsb, int start,unsigned long* number) 758 { 759 union ulong_char_union lcu; 760 761 if(lsb == 1){ 762 lcu.l_alpha[0] = buffer[start+0]; 763 lcu.l_alpha[1] = buffer[start+1]; 764 lcu.l_alpha[2] = buffer[start+2]; 765 lcu.l_alpha[3] = buffer[start+3]; 766 } /* ends if lsb = 1 */ 767 768 if(lsb == 0){ 769 lcu.l_alpha[0] = buffer[start+3]; 770 lcu.l_alpha[1] = buffer[start+2]; 771 lcu.l_alpha[2] = buffer[start+1]; 772 lcu.l_alpha[3] = buffer[start+0]; 773 } /* ends if lsb = 0 */ 774 *number = lcu.l_num; 775 } /* ends extract_ulong_from_buffer */ 776 777 void extract_short_from_buffer(char buffer[], int lsb, int start, short* number) 778 { 779 union short_char_union lcu; 780 781 if(lsb == 1){ 782 lcu.s_alpha[0] = buffer[start+0]; 783 lcu.s_alpha[1] = buffer[start+1]; 784 } /* ends if lsb = 1 */ 785 786 if(lsb == 0){ 787 lcu.s_alpha[0] = buffer[start+1]; 788 lcu.s_alpha[1] = buffer[start+0]; 789 } /* ends if lsb = 0 */ 790 791 *number = lcu.s_num; 792 } /* ends extract_short_from_buffer */ 793 794 void extract_ushort_from_buffer(char buffer[], int lsb, int start, unsigned short* number) 795 { 796 union ushort_char_union lcu; 797 798 if(lsb == 1){ 799 lcu.s_alpha[0] = buffer[start+0]; 800 lcu.s_alpha[1] = buffer[start+1]; 801 } /* ends if lsb = 1 */ 802 803 if(lsb == 0){ 804 lcu.s_alpha[0] = buffer[start+1]; 805 lcu.s_alpha[1] = buffer[start+0]; 806 } /* ends if lsb = 0 */ 807 808 *number = lcu.s_num; 809 } /* ends extract_ushort_from_buffer */ 810 811 void insert_short_into_buffer(char buffer[], int start, short number) 812 { 813 union short_char_union lsu; 814 815 lsu.s_num = number; 816 buffer[start+0] = lsu.s_alpha[0]; 817 buffer[start+1] = lsu.s_alpha[1]; 818 819 } /* ends insert_short_into_buffer */ 820 821 void insert_ushort_into_buffer(char buffer[], int start, unsigned short number) 822 { 823 union ushort_char_union lsu; 824 825 lsu.s_num = number; 826 buffer[start+0] = lsu.s_alpha[0]; 827 buffer[start+1] = lsu.s_alpha[1]; 828 } /* ends insert_short_into_buffer */ 829 830 void insert_long_into_buffer(char buffer[], int start, long number) 831 { 832 union long_char_union lsu; 833 834 lsu.l_num = number; 835 buffer[start+0] = lsu.l_alpha[0]; 836 buffer[start+1] = lsu.l_alpha[1]; 837 buffer[start+2] = lsu.l_alpha[2]; 838 buffer[start+3] = lsu.l_alpha[3]; 839 } /* ends insert_short_into_buffer */ 840 841 void insert_ulong_into_buffer(char buffer[], int start, unsigned long number) 842 { 843 union ulong_char_union lsu; 844 845 lsu.l_num = number; 846 buffer[start+0] = lsu.l_alpha[0]; 847 buffer[start+1] = lsu.l_alpha[1]; 848 buffer[start+2] = lsu.l_alpha[2]; 849 buffer[start+3] = lsu.l_alpha[3]; 850 } /* ends insert_ulong_into_buffer */ 851 852 int does_not_exist(const char* file_name) 853 { 854 FILE *image_file; 855 int result; 856 857 result = 1; 858 image_file = fopen(file_name, "rb"); 859 if(image_file != NULL){ 860 result = 0; 861 fclose(image_file); 862 } 863 return(result); 864 } /* ends does_not_exist */