C语言实现将彩色bmp图像转化为灰图、灰度图像反色

本文实例为大家分享了C语言实现将彩色bmp图像转化为灰图、灰度图像反色的具体代码，供大家参考，具体内容如下

彩色图像转灰度图像

彩色（24位）bmp图像结构：

typedef struct{
 bitmapFileHeader bfHeader;
 bitmapInfoHeader biHeader;
 unsigned char *imgData;
}bmp;

灰度（8位）bmp图像结构：

typedef struct{
 bitmapFileHeader bfHeader;
 bitmapInfoHeader biHeader;
 rgbQUAD palette[256];
 unsigned char *imgData;
}bmp;

bmp灰度图像比彩色图像多了一个调色板，调色板中每个元素的类型是一个RGBQUAD结构，占四个字节，其定义如下：

typedef struct{
 unsigned char rgbBlue;
 unsigned char rgbGreen;
 unsigned char rgbRed;
 unsigned char rgbReserved;

}rgbQUAD;

在实际的bmp图像中调色板：

代码实现将彩色bmp图像转化位灰值图像：

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#pragma pack(1)   //全紧凑模式

typedef struct {
 unsigned char bfType[2];
 unsigned int bfSize;
 unsigned short bfReserved1;
 unsigned short bfReserved2;
 unsigned int bfOffBits;
}bitmapFileHeader;

typedef struct {
 unsigned int biSize;
 unsigned int biWidth;
 unsigned int biHeight;
 unsigned short biPlanes;
 unsigned short biBitCount;
 unsigned int biCompression;
 unsigned int biSizeImage;
 unsigned int biXPixPerMeter;
 unsigned int biYPixPerMeter;
 unsigned int biClrUsed;
 unsigned int biClrImportant;
}bitmapInfoHeader;

typedef struct{
 unsigned char rgbBlue;
 unsigned char rgbGreen;
 unsigned char rgbRed;
 unsigned char rgbReserved;

}rgbQUAD;

typedef struct{
 bitmapFileHeader bfHeader;
 bitmapInfoHeader biHeader;
 rgbQUAD palette[256];
 unsigned char *imgData;
}bmp;

int main(){
 FILE *fp;
 if((fp=fopen("d:\Temp\\test.bmp","rb"))==NULL){
  perror("can not open file!");
  return -1;
 }
 //读入彩色bmp图像文件头，信息头和图像数据
 bitmapFileHeader bfHeader;
 fread(&bfHeader,14,1,fp);
 bitmapInfoHeader biHeader;
 fread(&biHeader,40,1,fp);
 int imSize=biHeader.biSizeImage;
 int width=biHeader.biWidth;
 int height=biHeader.biHeight;
 int bitCount=biHeader.biBitCount;
 int lineBytes=(width*bitCount+31)/32*4;

 fseek(fp,bfHeader.bfOffBits,SEEK_SET);
 unsigned char*imageData=(unsigned char*)malloc(imSize*sizeof(unsigned char));
 fread(imageData,imSize*sizeof(unsigned char),1,fp);
 fclose(fp);

 bmp b;
 int i,j,k;
 memcpy(&(b.bfHeader),&bfHeader,sizeof(bfHeader));
 memcpy(&(b.biHeader),&biHeader,sizeof(biHeader));
 b.bfHeader.bfOffBits=1078;  //因新增了调色板，需调整图像数据偏移位置
 b.biHeader.biBitCount=8;  //改变图像位数
 int lineBytes_new=(width*8+31)/32*4; //重新计算每行数据字节
 b.biHeader.biSizeImage=lineBytes_new*height; //改变图像数据大小
 b.bfHeader.bfSize=1078+b.biHeader.biSizeImage; //改变文件数据大小
 b.imgData=(unsigned char*)malloc(sizeof(unsigned char)*b.biHeader.biSizeImage);
 memset(b.imgData,0,sizeof(unsigned char)*b.biHeader.biSizeImage);
 for(i=0;i<256;i++){
  b.palette[i].rgbBlue=i;
  b.palette[i].rgbGreen=i;
  b.palette[i].rgbRed=i;
 }

 for(i=0;i<height;i++){
  for(j=0;j<width;j++){
   //将每一个像素都按公式y=B*0.299+G*0.587+R*0.114进行转化
   b.imgData[lineBytes_new*i+j]=imageData[lineBytes*i+j*3]*0.299+imageData[lineBytes*i+j*3+1]*0.587+imageData[lineBytes*i+j*3+2]*0.114;
  }
 }

 char savePath[]="D:\Temp\\save_test.bmp";
 FILE *f=fopen(savePath,"wb");
 if(f==NULL){
  perror("can not open file!");
  return -2;
 }
 fwrite(&b.bfHeader,sizeof(bitmapFileHeader),1,f);
 fwrite(&b.biHeader,sizeof(bitmapInfoHeader),1,f);
 fwrite(&b.palette,1024,1,f);
 fwrite(b.imgData,sizeof(unsigned char)*b.biHeader.biSizeImage,1,f);
 fclose(f);

 free(imageData);
 free(b.imgData);
 return 0;
}

代码效果：

灰度图像反色

int i,j;
 for(i=0;i<height;i++){
  for(j=0;j<width;j++){
   b.imgData[lineBytes*i+j]=255-imageData[lineBytes*i+j];
  }
 }

代码效果：

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