[PD] high pass filter for images

IOhannes m zmoelnig zmoelnig at iem.at
Tue Nov 6 09:48:33 CET 2007

punchik punchik wrote:
> hi i making a multituouch surface with pd, i want be
> able to filter the low and middle bands in the video
> from my web cam. im interesting in just letting the
> high images pass...
> is there something like a high pass filter for
> imagens?

in Gem:
[pix_convolve] does spatial convolution with a square kernel. fill it 
with the right coefficients to produce a spatial high-pass.
[pix_tIIR] does temporal filterin using an IIR-filter of settable 
length. fill with the right coefficients to produce a temporal 
high-pass. unfortunately the taps in the filter store the images only in 
  the usual precision (e.g. RGBA32), which might yield weird results

in pdp and Gridflow there are surely solutions (which i don't know; just 
go through the manual), for spatial filtering see [pdp_convolve] (pdp) 
and [#convolve] (Gridflow).

pdp will work with higher precission (16bit instead of 8bit per 
channel), and GridFlow will even allow you to use floating point.


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