colored lena to grayscale version

http://blog.csdn.net/rwjlqn/article/details/4742314 ！！！！！！！

#include <stdio.h>
#include <stdlib.h>

int main(){
    FILE *fp1,*fp2;
    unsigned int height,width;
    unsigned char r,g,b,Y,U,V,temp;
    width=height=0;
    fp1=fopen("D:\\lena.bmp","rb");
    fp2=fopen("D:\\my1.bmp","wb");
    if(!fp1||!fp2)
        exit(-1);
    fseek(fp1,0,SEEK_END);
    int flen=ftell(fp1);
    fseek(fp1,0,0);
    fseek(fp2,0,0);
    unsigned char i;
    for(int j=0;j<flen;j++){
        fread(&i,sizeof(unsigned char),1,fp1);
        if(j==18||j==19||j==20||j==21)
            width=i*(1<<(8*(j-18)))+width;
        if(j==22||j==23||j==24||j==25)
            height=i*(1<<(8*(j-22)))+height;
        //break;
        //fwrite(&i,sizeof(unsigned char),1,fp2);
    }
    //printf("%u\n%u\n",width,height);
    fseek(fp1,0,0);// from the beginning
    for(int j=0;j<flen;j++){
        if(j==54)
            break;
        fread(&i,sizeof(unsigned char),1,fp1);
        fwrite(&i,sizeof(unsigned char),1,fp2);
    }
    for(unsigned int h=0;h<=height;h++)
            for(unsigned int w=0;w<=width;w++){
                fread(&b,sizeof(unsigned char),1,fp1);
                fread(&g,sizeof(unsigned char),1,fp1);
                if(b==0&&g==0){
                    temp=0;
                    fwrite(&temp,sizeof(unsigned char),1,fp2);
                    fwrite(&temp,sizeof(unsigned char),1,fp2);
                    goto j;
                }
                fread(&r,sizeof(unsigned char),1,fp1);
                Y = (unsigned char)(0.3*r + 0.59*g + 0.11*b);
                U = (unsigned char)(0.493*(b-Y));
                V = (unsigned char)(0.877*(r-Y));
                //printf("%x,%x,%x\n",r,g,b);
                //printf("%x\n",Y);
                //goto mark;
                fwrite(&Y,sizeof(unsigned char),1,fp2);
                fwrite(&U,sizeof(unsigned char),1,fp2);
                fwrite(&V,sizeof(unsigned char),1,fp2);
j:;
        }
//mark:
            //fread(&r,sizeof(unsigned char),1,fp1);
//printf("%x\n",r);
    fclose(fp1);
    fclose(fp2);
    return 0;
}