[PD] gem/pdp: darkest filter

chris clepper cgc at humboldtblvd.com
Fri Nov 19 19:08:17 CET 2004

On Nov 19, 2004, at 7:09 AM, Tim Blechmann wrote:

> hi all,
> is there a filer for gem or pdp, that compares to frames and returns 
> the
> darkest pixel in a certain position?

pix_compare will do something similar by comparing the luma of each 
pixel in two streams, and either copies the right pixel if it's lighter 
('direction 1') or darker ('direction 0').  You could possibly modify 
that code to your needs as well.

> also, is there a way to analyze frames (to get the average brightness
> or something similar)?

I wrote some basic analysis objects like that a few years ago, but they 
didn't seem all that useful.  They were part of the yuv_ objects, which 
are no longer part of GEM, but they are still in CVS under some old 

Is there any general interest in having some specialized objects like 
this in GEM?  They are simple to write and quite easy to code up in 
SIMD for speed.


> thanks a lot ... tim

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