[問題] BMP檔讀寫問題

看板C_and_CPP (C/C++)作者appleloving (appleloving)時間14年前 (2011/10/20 22:48)推噓0(0推 0噓 2→)

留言2則, 2人參與討論串1/1

如題，朋友丟給我一個網頁叫我照上面的做，但是輸出的結果跟原圖差很多，而且也只顯示灰階圖。請各位幫我看一下問題出在哪。程式碼如下: #include <iostream> #include <fstream> #include <vector> using namespace std; int getBMP(const char *fname_s, const char *fname_t) { FILE *fp_s = NULL; // source file handler FILE *fp_t = NULL; // target file handler unsigned int x,y; // for loop counter unsigned int width, height; // image width, image height unsigned char *image_s = NULL; // source image array unsigned char *image_t = NULL; // target image array unsigned char R, G, B; // color of R, G, B unsigned int y_avg; // average of y axle unsigned int y_t; // target of y axle unsigned char header[54] = { 0x42, // identity : B 0x4d, // identity : M 0, 0, 0, 0, // file size 0, 0, // reserved1 0, 0, // reserved2 54, 0, 0, 0, // RGB data offset 40, 0, 0, 0, // struct BITMAPINFOHEADER size 0, 0, 0, 0, // bmp width 0, 0, 0, 0, // bmp height 1, 0, // planes 24, 0, // bit per pixel 0, 0, 0, 0, // compression 0, 0, 0, 0, // data size 0, 0, 0, 0, // h resolution 0, 0, 0, 0, // v resolution 0, 0, 0, 0, // used colors 0, 0, 0, 0 // important colors }; unsigned int file_size; // file size unsigned int rgb_raw_data_offset; // RGB raw data offset fp_s = fopen(fname_s, "rb"); if (fp_s == NULL) { cout<<"fopen fp_s error\n"; return -1; } // move offset to 10 to find rgb raw data offset fseek(fp_s, 10, SEEK_SET); fread(&rgb_raw_data_offset, sizeof(unsigned int), 1, fp_s); // move offset to 18 to get width & height; fseek(fp_s, 18, SEEK_SET); fread(&width, sizeof(unsigned int), 1, fp_s); fread(&height, sizeof(unsigned int), 1, fp_s); // move offset to rgb_raw_data_offset to get RGB raw data fseek(fp_s, rgb_raw_data_offset, SEEK_SET); image_s = (unsigned char *)malloc((size_t)width * height * 3); if (image_s == NULL) { cout<<"malloc images_s error\n"; return -1; } image_t = (unsigned char *)malloc((size_t)width * height * 3); if (image_t == NULL) { printf("malloc image_t error\n"); return -1; } fread(image_s, sizeof(unsigned char), (size_t)(long)width * height * 3, fp_s); y_avg=0+(height-1); for(y=height; y!=0; y--){ for(x=width; x!=0; x--){ R=*(image_s+3*(width*y+x)+2); G=*(image_s+3*(width*y+x)+1); B=*(image_s+3*(width*y+x)+0); y_t=y; *(image_t+3*(width*y_t+x)+2)=R; *(image_t+3*(width*y_t+x)+1)=G; *(image_t+3*(width*y_t+x)+0)=B; } } // write to new bmp fp_t = fopen(fname_t, "wb"); if (fp_t == NULL) { printf("fopen fname_t error\n"); return -1; } // file size file_size = width * height*3 + rgb_raw_data_offset; header[2] = (unsigned char)(file_size & 0x000000ff); header[3] = (file_size >> 8) & 0x000000ff; header[4] = (file_size >> 16) & 0x000000ff; header[5] = (file_size >> 24) & 0x000000ff; // width header[18] = width & 0x000000ff; header[19] = (width >> 8) & 0x000000ff; header[20] = (width >> 16) & 0x000000ff; header[21] = (width >> 24) & 0x000000ff; // height header[22] = height &0x000000ff; header[23] = (height >> 8) & 0x000000ff; header[24] = (height >> 16) & 0x000000ff; header[25] = (height >> 24) & 0x000000ff; // write header fwrite(header, sizeof(unsigned char), rgb_raw_data_offset, fp_t); // write image fwrite(image_t, sizeof(unsigned char), (size_t)(long)width * height * 3, fp_t); fclose(fp_s); fclose(fp_t); return 0; } int main() { getBMP("FRUIT2.bmp", "TEST_cpp.bmp"); } -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 182.235.170.44