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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