- oliver oliver@klingt.org [2017-04-12 14:21]:
hi, dear list !
i'm looking for an insight into some questions i ran into recently when i decided to give GEM a serious shot after all. please be patient, i'm probably spoiled by JITTER ...
PD 0.47.1 GEM 0.93.3 WINDOWS 7/64bit
1.) is there a way to do image processing (i.e. levels, contrast, satturation etc.) on the GPU ?
as far as i understood [pix_...] objects do all their processing with the CPU and others like [color] do it in openGL (thus GPU), is that right ? now, for big textures (1280x720 or bigger) that would be the preferable way of manipulating things, right ?
Asking a similar question recently on this list I got told that a lot is possible using shaders. See if you have a folder named 10.glsl on your OS somewhere that could hold Gem examples for shaders.
Searching the mailing list archive https://lists.puredata.info/pipermail/pd-list/ for "shaders" https://lists.puredata.info/search?P=shaders&G=Pd-list&HITSPERPAGE=2... might give you results as well.
2.) i'm looking for objects that do "compositing", i.e. ways to overlay two pix sources. apart from the ones existing (add, multiplay, subtract, mix) , i would love to have the well-known (AE,vegas, etc.) compositing modes like "darken", "lighten", "dodge" "difference" etc. - but also chromakeying !
is this possible ? and is it possible to do in opengl rather than with a [pix_] object ?
Look for help patches 12.blending.pd 13.maskDancer.pd 14.takeAlpha.pd 15.pix_alpha.pd
and the [pix_chroma_key] object and its documentation perhaps.