I=imread（‘china.jpg‘）;
I1=rgb2gray（I）;
[thrsorhkeepapp]=ddencmp（‘den‘‘wv‘I1）;
I2=wdencmp（‘gbl‘I1‘sym4‘2thrsorhkeepapp）;
I3=medfilt2（I2[9?9]）;
I4=imresize（I30.2‘bicubic‘）;
BW1=edge（I4‘sobel‘）;
BW2=edge（I4‘roberts‘）;
BW3=edge（I4‘prewitt‘）;
h=fspecial（‘gaussian‘5）;
figure;sub