Haar过滤图像

Question

I use Lena image 256x256 uint8 and I've applied Haar filter

dwt2(startImage,'haar','mode','sym');

when I see the horizontal, vertical and diagonal filtered images , I see Lena details but as if they were in black and white, and the correspondent matrices have negatives entries (!). And if I see the average image, I just see a white square. Searching for help in Matlab 7.11, I saw the example, it works for a MAT file, and using wcodemat function, but I need to load the image via

J = imread('Lena.tif');

beacuse I am planing to work with a great number of images in order to train a discriminant etc. How can I get the scaled images correctly? Help me to solve this issue.

Answer 1

我只需要在每个分解级别中使用mat2grey即可。