[Sidefx-houdini-list] COPS - Average Colour Luminance in Image
jeff at sidefx.com
Mon Apr 23 10:06:48 EDT 2007
Another way to find the average rgb values of an image is to use a Scale
COP and scale it to 1x1 using the pixel filter. Well I had to use two
Scale COPs: one to go to 2x2 and then down to 1x1.
On Fri, 2007-20-04 at 16:23 -0400, Mark Alexander wrote:
> > and this has brought the result within a decent range.
> > (The result is 3.05 for a white image)
> > - I'm now multiplying by a 'magic' number
> > to get the results between 0 and 1
> Ah, right. I forgot to mention you should run it through a Mono COP
> first to change RGB -> lum, and then just read the Red channel into
> CHOPs. It's 3x higher than normal because of the 3 RGB channels. Sorry,
> forgot about that :) At least that should reduce the 0.05 error to
> around ~0.01, which is probably acceptable.
> Sidefx-houdini-list mailing list
> Sidefx-houdini-list at sidefx.com
Jeff Wagner, jeff at sidefx.com, Senior Technology Consultant
Side Effects Software, www.sidefx.com, Toronto, Ontario, M5V 3E7
tel: (416) 504-9876, fax: (416) 504-6648
More information about the Sidefx-houdini-list