读取bmp图片文件，并获取任意一点的RGB值，并可按任意指定大小保存bmp文件

#include "img.h" #define __WIN32__ #ifdef __WIN32__ #include <math.h> #include <stdio.h> // BMP文件头 #pragma pack(push,2) typedef struct { uint16_t bfType; // 文件类型 uint32_t bfSize; // 文件大小 uint16_t bfReserved1; // 保留位 uint16_t bfReserved2; // 保留位 uint32_t bfOffBits; // 数据偏移位置 }BMPFILEHEADER; #pragma pack(pop) // BMP信息头 typedef struct { uint32_t biSize; /*此结构大小*/ int32_t biWidth; /*图像宽度*/ int32_t biHeight; // 图像高度 uint16_t biPlanes; // 调色板数量 uint16_t biBitCount; // 每个象素对应的位数，24：24位图，32：带alpha通道的24位图 uint32_t biCompression; // 压缩 uint32_t biSizeImage; // 图像大小 int32_t biXPelsPerMeter;// 横向分辨率 int32_t biYPelsPerMeter;// 纵向分辨率 uint32_t biClrUsed; // 颜色使用数 uint32_t biClrImportant; // 重要颜色数 }BMPINFOHEADER; /*BMP 调色板信息结构*/ typedef struct tagRGBQUAD { uint8_t rgbBlue; uint8_t rgbGreen; uint8_t rgbRed; uint8_t rgbReserved; } RGBQUAD; #define WIDTHBYTES(i) ((i+31)/32*4) /* *读取bmp格式文件，同时把24位彩色转换成256色的灰度图象 * *img: 图象数据存储对象． ＊ *filename: BMP文件名． */ static int8_t read_image_bmp_win32(image_t *img, const int8_t *filename) { int i, j, k, pixel_size; uint8_t temp; FILE *file; BMPFILEHEADER bmpFile; BMPINFOHEADER bmpInfo; RGBQUAD rgb[256]; uint8_t *img_data, *ptr_cur; uint32_t image_size,line_bytes,offset; file = fopen(filename,"rb "); if (file == NULL) { printf("Open File Error \n"); return -1; } /*获取BMP文件头和信息头*/ rewind(file); fread(&bmpFile, sizeof(BMPFILEHEADER), 1, file); fread(&bmpInfo, sizeof(BMPINFOHEADER), 1, file); /*验证文件类型 */ if (bmpFile.bfType != 0x4D42) { printf("File Type Error \n"); fclose(file); return -1; } /*获取图像色彩数 */ pixel_size = bmpInfo.biBitCount >> 3; img->height = bmpInfo.biHeight; img->width = bmpInfo.biWidth; line_bytes = img->width * pixel_size + 3 - ((img->width * pixel_size + 3) & 3); image_size = img->height * line_bytes; img_data = (uint8_t*)malloc(image_size * sizeof(uint8_t)); if(NULL == img_data ) { printf("malloc img_data error,not enough memory !\n"); fclose(file); return -1; } img->release_image(img); img->data = (uint8_t*)malloc(img->height * img->width); if(NULL == img->data ) { printf("malloc img_data error,not enough memory !\n"); free(img_data); fclose(file); return -1; } offset = 1 << bmpInfo.biBitCount; /*读取颜色表*/ if(bmpInfo.biBitCount <= 8) fread(rgb,4,offset,file); /* 读取图象数据*/ fread(img_data ,1, image_size, file); if(1 == pixel_size)/*256色BMP*/ { for( i=0; i<img->height; ++i) { memcpy(img->data + img->width * i,img_data + ((img->height - i - 1) * line_bytes),img->width); } } else if(3 == pixel_size)/*24位BMP*/ { init_RGB_table(); k = 0; /*转换RGB格式的亮度值Y*/ for (i=0; i<img->height; i++) { for (j=0; j<img->width; j++) { ptr_cur = img_data + ((img->height - i - 1) * line_bytes) + j * pixel_size; temp = R[*(ptr_cur + 2)] + G[*(ptr_cur + 1)] + B[*ptr_cur]; memcpy(img->data + k++, &temp,1); } } } else { printf("is not support this colors now!\n"); } free(img_data); return 0; } /* *保存成ＢＭＰ文件（２５６灰度图象，即yuv格式的y值） * *img：image_t对象． * *filename: 文件名. */ static int8_t save_image_data_bmp_win32(image_t *img, const int8_t *filename) { FILE *fp; uint16_t line_bytes; // int *bmp256; int32_t i,j,temp; uint32_t width,height; BMPFILEHEADER bmpheader; BMPINFOHEADER bmpinfo; RGBQUAD rgb[256]; width = img->width; height = img->height; if(!img) { printf("img paramer is NULL!\n"); return -1; } /*初始化BMP文件头和信息头*/ memset(&bmpheader,0,sizeof(BMPFILEHEADER)); memset(&bmpinfo,0,sizeof(BMPINFOHEADER)); bmpheader.bfType = 0x4D42; bmpheader.bfSize = sizeof(BMPFILEHEADER) + sizeof(BMPINFOHEADER) + 256 * 4 + img->width * img->height * sizeof(uint8_t); bmpheader.bfOffBits = sizeof(BMPFILEHEADER) + sizeof(BMPINFOHEADER) + 256 * 4; bmpinfo.biBitCount = 8; bmpinfo.biHeight = img->height; bmpinfo.biWidth = img->width; bmpinfo.biSize = sizeof(BMPINFOHEADER); /*初始化RGB表*/ for(i=0; i<256; ++i) { rgb[i].rgbBlue = i; rgb[i].rgbGreen = i; rgb[i].rgbRed = i; rgb[i].rgbReserved = 0; } /*新建一个bmp文件*/ fp = fopen(filename,"wb"); if (fp == NULL){ printf("can not open the file!\n"); return -1; } fwrite(&bmpheader,sizeof(BMPFILEHEADER),1,fp); fwrite(&bmpinfo,sizeof(BMPINFOHEADER),1,fp); fwrite(rgb,4,256,fp); line_bytes = (img->width + 3) - ((img->width + 3) & 3); for(i=0; i<img->height; ++i) { fwrite(img->data + (img->height - i - 1) * img->width ,1,line_bytes,fp); } fclose(fp); return 0; } #endif static int8_t read_image_y_bmp(image_t *img, const int8_t *filename) { #ifdef __WIN32__ return read_image_bmp_win32(img,filename); #else return 0; #endif } static int8_t save_image_data_bmp(image_t *img, const int8_t *filename) { #ifdef __WIN32__ return save_image_data_bmp_win32(img, filename); #else return 0; #endif } /* *默认初始化回调函数 * *img: 初始化对象． */ void init_image_callback_bmpio(image_t *img) { img->read_image = read_image_y_bmp; img->save_image = save_image_data_bmp; }