Category Archives: wavelet

Wavelet Image Compression

Wavelet Fixes

*Small bug fixed (decidedly non-power-of-2 images sometimes had important wavelet-coefficients zeroed out). Thanks, Christian Lange!*
Wavelet code updated to version 2.5.2 (including source). Improved the quantiser-selection for bit-limits (i.e. file-size) a LOT (was a bit stupid before – I only optimised for the smallest difference in maximum and minimum mean square error) -> much better results for same size, changed compile-settings slightly (should be faster) and added a bitplane / quantiser display to the GUI. Get it here!

Integer Math in CAS

got this week off (all of 4head does in fact), so i started to do some more research on my wavelet-code. spent two days in mathematica trying to analyse error-propagation in the wavelet-transform, proved it is symmetric (just did that as a check), and now it turns out it doesn’t work for some reason (just kinda, but it should be exact)…argh!

wavelet kompressor 2.1

wavelet.zip updated to version 2.1. it had serious bugs in the quality based quantiser-selection (one was related to not returning lossless “solutions” when they were asked for, the other very often returned large solutions, although better (i.e. smaller) ones were available).