C语言二值图像模拟灰值图像显示 C语言实现二值图像模拟灰值图像显示效果
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图案法
图案法(patterning)是指灰度可以用一定比例的黑白点组成的区域表示，从而达到整体图象的灰度感。黑白点的位置选择称为图案化。
下面介绍的一种设计标准图案的算法，是由Limb在1969年提出的。
先以一个2×2的矩阵开始：
通过递归关系有：
其中Mn和Un均为2n×2n的方阵，Un的所有元素都是1。
根据这个算法M2如下，为16级灰度的标准图案：
M3(8×8阵)比较特殊，称为Bayer抖动表。M4是一个16×16的矩阵。
M3 表模拟灰值图像显示效果：
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#pragma pack(1) //全紧凑模式
typedef struct {
unsigned char bfType[2];
unsigned long bfSize;
unsigned short bfReserved1;
unsigned short bfReserved2;
unsigned long bfOffBits;
}bitmapFileHeader;
typedef struct {
unsigned long biSize;
unsigned long biWidth;
unsigned long biHeight;
unsigned short biPlanes;
unsigned short biBitCount;
unsigned long biCompression;
unsigned long biSizeImage;
long biXPixPerMeter;
long biYPixPerMeter;
unsigned long biClrUsed;
unsigned long 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_gray.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;
memcpy(&(b.bfHeader),&bfHeader,sizeof(bfHeader));
memcpy(&(b.biHeader),&biHeader,sizeof(biHeader));
b.imgData=(unsigned char*)malloc(sizeof(unsigned char)*imSize);
memset(b.imgData,0,sizeof(unsigned char)*imSize);
for(int i=0;i<256;i++){
b.palette[i].rgbBlue=i;
b.palette[i].rgbGreen=i;
b.palette[i].rgbRed=i;
}
int i,j,temp;
unsigned char bayer[8][8]={
0,32,8,40,2,34,10,42,
48,16,56,24,50,18,58,26,
12,44,4,36,14,46,6,38,
60,28,52,20,62,30,54,22,
3,35,11,43,1,33,9,41,
51,19,59,27,49,17,57,25,
15,47,7,39,13,45,5,37,
63,31,55,23,61,29,53,21
};
for(i=0;i<height;i++){
for(j=0;j<width;j++){
temp=imageData[lineBytes*i+j];
if((temp>>2)>bayer[i&7][j&7])
b.imgData[lineBytes*i+j]=255;
else
b.imgData[lineBytes*i+j]=0;
}
}
char savePath[]="D:\Temp\\save_test.bmp";
FILE *f_save=fopen(savePath,"wb");
if(f_save==NULL){
perror("can not open file!");
return -2;
}
fwrite(&b.bfHeader,sizeof(bitmapFileHeader),1,f_save);
fwrite(&b.biHeader,sizeof(bitmapInfoHeader),1,f_save);
fwrite(&b.palette,1024,1,f_save);
fwrite(b.imgData,sizeof(unsigned char)*b.biHeader.biSizeImage,1,f_save);
fclose(f_save);
free(imageData);
free(b.imgData);
getchar();
return 0;
}
代码效果：
抖动法
假设灰度级别的范围从b(black)到w(white)，中间值t为(b+w)/2，对应256级灰度，b=0,w=255,t=127.5。设原图中象素的灰度为g，误差值为e，则新图中对应象素的值用如下的方法得到：
if g > t then 打白点 e=g-w else 打黑点 e=g-b 3/8 × e 加到右边的象素 3/8 × e 加到上边的象素 1/4 × e 加到右上方的象素
实现代码：
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#pragma pack(1) //全紧凑模式
typedef struct {
unsigned char bfType[2];
unsigned long bfSize;
unsigned short bfReserved1;
unsigned short bfReserved2;
unsigned long bfOffBits;
}bitmapFileHeader;
typedef struct {
unsigned long biSize;
unsigned long biWidth;
unsigned long biHeight;
unsigned short biPlanes;
unsigned short biBitCount;
unsigned long biCompression;
unsigned long biSizeImage;
long biXPixPerMeter;
long biYPixPerMeter;
unsigned long biClrUsed;
unsigned long 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_gray.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;
memcpy(&(b.bfHeader),&bfHeader,sizeof(bfHeader));
memcpy(&(b.biHeader),&biHeader,sizeof(biHeader));
b.imgData=(unsigned char*)malloc(sizeof(unsigned char)*imSize);
memset(b.imgData,0,sizeof(unsigned char)*imSize);
for(int i=0;i<256;i++){
b.palette[i].rgbBlue=i;
b.palette[i].rgbGreen=i;
b.palette[i].rgbRed=i;
}
int i,j,temp;
double e,f;
for(i=0;i<height;i++){
for(j=0;j<width;j++){
b.imgData[lineBytes*i+j]=imageData[lineBytes*i+j]; //拷贝数据
}
}
for(i=0;i<height;i++){
for(j=0;j<width;j++){
temp=b.imgData[lineBytes*i+j];
if(temp>128){
b.imgData[lineBytes*i+j]=255;
e=(float)(temp-255);
}
else{
b.imgData[lineBytes*i+j]=0;
e=(float)temp;
}
if(j<width-1){
f=b.imgData[lineBytes*i+j+1];
f+=3.0/8.0*e;
b.imgData[lineBytes*i+j+1]=(unsigned char)f; //向右传播
}
if(i<height-1){
f=b.imgData[lineBytes*(i+1)+j];
f+=3.0/8.0*e;
b.imgData[lineBytes*(i+1)+j]=(unsigned char)f; //向上传播
f=b.imgData[lineBytes*(i+1)+j+1];
f+=1.0/4.0*e;
b.imgData[lineBytes*(i+1)+j+1]=(unsigned char)f; //向右上传播
}
}
}
char savePath[]="D:\Temp\\save_test.bmp";
FILE *f_save=fopen(savePath,"wb");
if(f_save==NULL){
perror("can not open file!");
return -2;
}
fwrite(&b.bfHeader,sizeof(bitmapFileHeader),1,f_save);
fwrite(&b.biHeader,sizeof(bitmapInfoHeader),1,f_save);
fwrite(&b.palette,1024,1,f_save);
fwrite(b.imgData,sizeof(unsigned char)*b.biHeader.biSizeImage,1,f_save);
fclose(f_save);
free(imageData);
free(b.imgData);
getchar();
return 0;
}
代码效果：
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