img=imread(\'C:\Users\GWL\Desktop\arun.jpg\');
imshow(img,\'Border\',\'tight\');
frame=getframe(gcf);
% method 1
imwrite(frame.cdata(:,:,1),\'test.png\');
% method 2
imm = frame2im(frame);
imwrite(imm,\'test2.png\');
imshow显示图片

test.png(灰度图像)

test2.png

