[PD] Gem: alpha blending without loss of brightness

cyrille henry cyrille.henry at la-kitchen.fr
Wed Jan 23 18:32:27 CET 2008


hello,
you can set alpha blend type to be the maxinmum of each images.

cyrille


Georg Holzmann a écrit :
> Hallo!
> 
> I have again a basic alpha blending problem, where I don't find a solution:
> 
> For example I have two images (A + B), which are overlapping at a small 
> part (C):
> 
> ----------------
> | image A      |
> |              |
> |          |------------------
> |          | C |             |
> -----------|----             |
>            |                 |
>            |  image B        |
>            -------------------
> 
> Now I want that image A and image B looks normal (unchanged) and in the 
> overlapping part the two images are added so that one sees both - and 
> all this with openGL commands (not pix_add or similar, because I have 
> lots of such regions).
> 
> OK, I gave all images an alpha value of 0.5, but then the whole image 
> losses brightness.
> 
> So my question: is there a way to get this alpha blending and without a 
> loss of brightness in the images ? or can I "renormalize" this effect 
> somehow (re-increase the brightness) ?
> (see attached patch where I illustruted this problem with 2 colored 
> rectangles)
> 
> Thanks for any hint,
> LG
> Georg
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> PD-list at iem.at mailing list
> UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list




More information about the Pd-list mailing list