decimation in dwt is

i am performing following operation on 256*256 lena image after execution four bands are of size 136*136 according to me it should be of 128*128 pls clear.

[Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('db9'); [LLD,LHD,HLD,HHD]=dwt2(GRAY,Lo_D,Hi_D);

[Lokesh Ravindranathan]

It seems like wfilters and dwt2 are not MATLAB toolbox functions. Maybe, you are using a window inside of these functions. If you provide a better insight into the code, the inconsistency can be explained.

Answer 1

[Wayne King]

The problem is that you should first set the dwtmode to 'per' to get the subband sizes you expect.

   dwtmode('per');
   load woman; % 256x256
   [Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('db9'); 
   [LLD,LHD,HLD,HHD]=dwt2(X,Lo_D,Hi_D);