estimating the background pixel values

hi all

the need to extract the background pixel values of an image. for this i
have written the following code:

background=imopen(I,strel('rectangle',[480,640]));

i need the background pixel values for the pixels in the image and here
I is a gray scale image with size 480*640.

could anyone tell me if this is the correct code or does this need any
changes. plz explain

thanks in advance

Ashwin Start a New Thread