specifying bpp of an image

Most of compression analysis use different value of bpp. For example Lena image in 0.5 bpp, 0.25bpp and 0.125bpp. How can we adjust the bpp on same image? tq in advance.

Answer 1

[Walter Roberson]

You start with the least compressed version (ideally with the version with no compression done), and you throw more and more information away. For example,

H = uint8(Orig(1:2:end, :, :) + Orig(2:2:end, :, :))/2);
Q = uint8((H(:, 1:2:end, :) + H(:, 2:2:end, :))/2);
S = uint8((Q(1:2:end, 1:2:end, :) + Q(2:2:end, 2:2:end, :))/2);

H will be half of the original size, Q throws away half of that so it will be 1/4 of the original size, S throws away 3/4 of that so it will be 1/16 of the original size...