非线性算子-锐化I=imread('');subplot(2, 2, 1);imshow(I);title('OrigMap');J=filter2(fspecial('sobel'), I);subplot(2, 2, 2);imshow(J);title('SobelMap');K=filter2(fspecial('prewitt'), I);subplot(2, 2, 3);imshow(K);title('preMap');L=filter2(fspecial('log'), I);subplot(2, 2, 4);imshow(L);title('logMap');