edit-calculating PSNR

As in my previous post

MSE = mean2((single(image1) - single(image2)).^2);

i get error,matrix dimension must agree,please help

Answer 1

[Walter Roberson]

MSE is not defined in that situation.

MSE is only define between a reference image and an altered version of the image of the same size.

If you were to "decompress" the wavelets back to a full sized image, then it would be meaningful to calculate the MSE between the original image and the one produced by the compression + decompression process.

Answer 2

[Image Analyst]

"Matrix dimension" basically means the size of your image. Your images must both be of the same size, not just laterally but also in the number of colors. So you can't subtract a grayscale image from a color one or vice versa. Do this and see what it says:

[rows1 columns1 numberOfColorChannels1] = size(image1)
[rows2 columns2 numberOfColorChannels2] = size(image2)

[kash]

[ca1,ch,cv,cd] = dwt2(y1,'haar');

i want to find mse between,y1 and ca1;

the size of y1 is 240x320

soze of ca1 is 120x160

[Image Analyst]

Well there you go. Matrix dimensions are not the same, just like it said. Plus, like Walter said, this is not really meaningful (assuming you resized them to match) since of course you know you will get a big number because it's a low pass version of the original image. Nothing really surprising there, or worth measuring I don't think.