extract 4*4 matrix from 8*8

sir i have 256*256 image i want to extract top left 4*4 matrix from every 8*8 blocks of that image..please send me the code

Answer 1

[Andrei Bobrov]

blockproc(yourimage,[8 8],@(x)x.data(1:4,1:4))

[Jitesh Bhanushali]

sir what is code if i want to add zeros to 4*4 matrix and make it 8*8 in the image

[Azzi Abdelmalek]

blockproc(im,[8 8],@(x) [x.data(1:4,1:4) zeros(4);zeros(4,8)]);