On Tue, Dec 04, 2001 at 03:10:18AM +0800, Orlando Andico wrote: > > I checked out QImage Pro because it's much-recommended for post-processing > digital camera images. This software makes the claim that its > interpolation is far superior to that used by Photoshop because it uses a > Lanczos function as a convolution mask. >
I remember a technique called Lanczos smoothing used in the design of digital filters. It's used to attenuate the ripples in an FIR filter that happen when you truncate the (in general, infinitely long) series of Fourier coefficients that represent the filter (the Gibbs phenomenon). There are "sigma factors" computed here that are multiplied with the coefficients that eliminate the worst effects of the Gibbs phenomenon. Since interpolation generally involves low-pass filtering, I would imagine that this might be what it means. (is it?) This is what I get for listening too closely in Dr. Guevara's DSP classes! :) -- Rafael R. Sevilla <[EMAIL PROTECTED]> +63(2) 8177746 ext. 8311 Programmer, Inter.Net Philippines +63(917) 4458925 http://dido.engr.internet.org.ph/ OpenPGP Key ID: 0x5CDA17D8 Heute die Welt und Morgen das Sonnensystem! _ Philippine Linux Users Group. Web site and archives at http://plug.linux.org.ph To leave: send "unsubscribe" in the body to [EMAIL PROTECTED] To subscribe to the Linux Newbies' List: send "subscribe" in the body to [EMAIL PROTECTED]
