its called sampling operator.it increases the sampling rate by inserting zeros between samples. example: x = [1 2 3 4] y = upsample(x,3) x = 1 2 3 4 y = 1 0 0 2 0 0 3 0 0 4 0 0
you can directly apply DWT by using dwt2 command. example:
I=imread('rice.png'); [LL,LH,HL,HH] = dwt2(I,'db9'); figure('Name','DWT Subband Images','NumberTitle','off'); subplot(2,2,1); imshow(LL,[]);title('LL'); subplot(2,2,2); imshow(LH,[]);title('LH'); subplot(2,2,3); imshow(HL,[]);title('HL'); subplot(2,2,4); imshow(HH,[]);title('HH'); >>
