概述
本文实例为大家分享了C语言实现二值图像模拟灰值图像显示效果的具体代码,供大家参考,具体内容如下
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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