c语言数字图像处理（二）：图片放大与缩小-双线性内插法和仿射变换scaling.rar

#include <stdio.h> #include <stdlib.h> #include <string.h> #define GRAY_LEVELS 255 struct bmpfileheader{ unsigned short filetype; unsigned long filesize; short reserved1; short reserved2; unsigned long bitmapoffset; }; struct bitmapheader{ unsigned long size; long width; long height; unsigned short planes; unsigned short bitsperpixel; unsigned long compression; unsigned long sizeofbitmap; unsigned long horzres; unsigned long vertres; unsigned long colorsused; unsigned long colorsimp; }; struct ctstruct{ unsigned char blue; unsigned char green; unsigned char red; }; union short_char_union{ short s_num; char s_alpha[2]; }; union int_char_union{ int i_num; char i_alpha[2]; }; union long_char_union{ long l_num; char l_alpha[4]; }; union float_char_union{ float f_num; char f_alpha[4]; }; union ushort_char_union{ short s_num; char s_alpha[2]; }; union uint_char_union{ int i_num; char i_alpha[2]; }; union ulong_char_union{ long l_num; char l_alpha[4]; }; int get_image_size(const char* file_name, long* rows, long* cols); void extract_long_from_buffer(char buffer[], int lsb, int start, long* number); void extract_ulong_from_buffer(char buffer[], int lsb, int start,unsigned long* number); void extract_short_from_buffer(char buffer[], int lsb, int start, short* number); void extract_ushort_from_buffer(char buffer[], int lsb, int start, unsigned short* number); void insert_short_into_buffer(char buffer[], int start, short number); void insert_ushort_into_buffer(char buffer[], int start, unsigned short number); void insert_long_into_buffer(char buffer[], int start, long number); void insert_ulong_into_buffer(char buffer[], int start, unsigned long number); short **allocate_image_array(long length, long width); int free_image_array(short **the_array, long length); void create_allocate_bmp_file(const char *file_name, struct bmpfileheader *file_header, struct bitmapheader *bmheader); void read_bmp_file_header(const char *file_name, struct bmpfileheader *file_header); void read_bm_header(const char* file_name, struct bitmapheader *bmheader); void read_bmp_image(const char* file_name, short** array); int calculate_pad(long width); void write_bmp_image(const char* file_name, short **array); int does_not_exist(const char* file_name); void flip_image_array(short** the_image, long rows, long cols); void read_color_table(const char* file_name, struct ctstruct* rgb, int size); void bilinera_interpolation(short** in_array, short height, short width, short** out_array, short out_height, short out_width); // .\scaling.exe a.bmp b.bmp 500 600 int main(int argc, char const *argv[]) { char *cc; long h, w; short **in_array, **out_array; struct bmpfileheader bmp_file_header; struct bitmapheader bmheader; short out_width, out_height; if(argc < 4){ printf("\nusage: bmp scaling_file scaling_width scaling_height\n"); exit(-1); } if(does_not_exist(argv[1])){ printf("\nERROR input file %s does not exist", argv[1]); exit(0); } cc = strstr(argv[1], ".bmp"); if(cc == NULL){ printf("\nERROR %s must be a bmp file", argv[1]); exit(0); } cc = strstr(argv[2], ".bmp"); if(cc == NULL){ /* create a bmp */ printf("\nERROR %s must be a bmp file name", argv[2]); exit(0); } out_width = atoi(argv[3]); out_height = atoi(argv[4]); get_image_size(argv[1], &h, &w); in_array = allocate_image_array(h, w); read_bmp_image(argv[1], in_array); out_array = allocate_image_array(out_height, out_width); bmheader.height = out_height; bmheader.width = out_width; create_allocate_bmp_file(argv[2], &bmp_file_header, &bmheader); bilinera_interpolation(in_array, h, w, out_array, out_height, out_width); write_bmp_image(argv[2], out_array); // bmheader.height = h; // bmheader.width = w; // create_allocate_bmp_file(argv[2], &bmp_file_header, &bmheader); // write_bmp_image(argv[2], in_array); free_image_array(in_array, h); free_image_array(out_array, out_height); return 0; } int is_in_array(short x, short y, short height, short width) { if (x >= 0 && x < width && y >= 0 && y < height) return 1; else return 0; } void bilinera_interpolation(short** in_array, short height, short width, short** out_array, short out_height, short out_width) { double h_times = (double)out_height / (double)height, w_times = (double)out_width / (double)width; short x1, y1, x2, y2, f11, f12, f21, f22; double x, y; for (int i = 0; i < out_height; i++){ for (int j = 0; j < out_width; j++){ x = j / w_times; y = i / h_times; /* 仿射变换 逆时针旋转 45度 + 平移 */ // y = i + j - out_width / 2 - (out_height - height) / 2; // x = i - j + out_width / 2 - (out_height - height) / 2; /* 仿射变换水平偏移 */ // y = i; // x = j - i / 2; x1 = (short)(x - 1); x2 = (short)(x + 1); y1 = (short)(y + 1); y2 = (short)(y - 1); f11 = is_in_array(x1, y1, height, width) ? in_array[y1][x1] : 0; f12 = is_in_array(x1, y2, height, width) ? in_array[y2][x1] : 0; f21 = is_in_array(x2, y1, height, width) ? in_array[y1][x2] : 0; f22 = is_in_array(x2, y2, height, width) ? in_array[y2][x2] : 0; out_array[i][j] = (short)(((f11 * (x2 - x) * (y2 - y)) + (f21 * (x - x1) * (y2 - y)) + (f12 * (x2 - x) * (y - y1)) + (f22 * (x - x1) * (y - y1))) / ((x2 - x1) * (y2 - y1))); } } } void read_color_table(const char* file_name, struct ctstruct* rgb, int size) { int i; char buffer[10]; FILE *fp; fp = fopen(file_name, "rb"); fseek(fp, 54, SEEK_SET); for(i=0; i<size; i++){ fread(buffer, 1, 1, fp); rgb[i].blue = buffer[0]; fread(buffer, 1, 1, fp); rgb[i].green = buffer[0]; fread(buffer, 1, 1, fp); rgb[i].red = buffer[0]; fread(buffer, 1, 1, fp); /* fourth byte nothing */ } /* ends loop over i */ fclose(fp); } /* ends read_color_table */ void read_bmp_image(const char* file_name, short** array) { FILE *fp; int i, j; int negative = 0, pad = 0, place = 0; long colors = 0, height = 0, //position = 0, width = 0; struct bmpfileheader file_header; struct bitmapheader bmheader; struct ctstruct rgb[GRAY_LEVELS+1]; unsigned char uc; read_bmp_file_header(file_name, &file_header); read_bm_header(file_name, &bmheader); if(bmheader.bitsperpixel != 8){ printf("\nCannot read image when bits per pixel is not 8"); exit(1); } if(bmheader.colorsused == 0) colors = GRAY_LEVELS + 1; else colors = bmheader.colorsused; read_color_table(file_name, (struct ctstruct*)&rgb, colors); fp = fopen(file_name, "rb"); fseek(fp, file_header.bitmapoffset, SEEK_SET); width = bmheader.width; if(bmheader.height < 0){ height = bmheader.height * (-1); negative = 1; } else height = bmheader.height; pad = calculate_pad(width); for(i=0; i<height; i++){ for(j=0; j<width; j++){ place = fgetc(fp); uc = (place & 0xff); place = uc; array[i][j] = rgb[place].blue; } /* ends loop over j */ if(pad != 0){ //position = fseek(fp, pad, SEEK_CUR);