x=imread('mj.jpg');
x=double(x);
r=x(:,:,1);g=x(:,:,2);b=x(:,:,3);
xgray=0.2126*r+0.7152*g+0.0722*b;
imagesc(xgray);colormap(gray)
xb=xgray(81:88,81:88);
imagesc(xb)

x=imread('mj.jpg');
x=double(x);
r=x(:,:,1);g=x(:,:,2);b=x(:,:,3);
xgray=0.2126*r+0.7152*g+0.0722*b;
imagesc(xgray);colormap(gray)
xb=xgray(81:88,81:88);
imagesc(xb)