On Dec 21, 2010, at 1:08 PM, Patrick Sheffield wrote: > > ...between how Quartz Composer processes the Screen blend mode and how Final > Cut Pro and Motion do it?
I actually don't have an answer, but it reminded me of a question I asked some time ago regarding the QC Addition blend mode patch and a case where it didn't seem to do what I'd expect (see message pasted below - perhaps unrelated, but I never really was able to explain it in that case either) On Aug 4, 2009, at 6:53 PM, kingLuma wrote: > In a compositing program (like Adobe After Effects for example), if I use the > Add blend mode to composite the separated R, G, and B channels of an image as > separate layers in an AE Comp, the result perfectly matches the original > image. I'm trying to do the same thing in QC (compositing R and G with an > Addition patch and then adding the result to the B channel with another > Addition patch and then rendering that result using a sprite renderer), and I > find that the result is obviously brighter than the original image. > > I've tried a jpeg brought in with an Image Importer patch, and a QT Movie > brought in with a Movie Loader patch and I see the same problem in each > case... Whether the "Enable Color Correction" checkbox on the importer > patches is enabled or not seems to make no visible difference in the result. > My method for separating the color channels involves using GLSL Shader > patches within Render in Image patches, and for those Render In Image patches > "Disable Color Correction" is unchecked (the image goes even brighter if this > checkbox is enabled). > > Comparing my R, G, and B channels out of QC individually, they seem to match > what I would get (for R, G, B) in AE so it seems the channel separation is > correct and the problem is elsewhere (maybe in the Addition patch > compositing?) > > Would adding R, G, and B using Addition patches in QC be expected to result > in the original image (R+G+B = RGB) ? If so, is there something I'm missing > that would cause what I'm seeing ? Any ideas appreciated. Thanks. > > ______ > > kingLu > > > > This is an image screened over itself in Final Cut Pro/Motion: > > <fcs1.jpg> > > And in Quartz Composer: > > <quartz1.jpg> > > In Quartz Composer it's flatter and considerably more red than FCP. > > If I perform a Screen Blend (the inverse of the multiplication of the > inverse), I get the same result as Quartz, but I need to figure out what > FCP/Motion are doing differently. > > Does anyone have any insight? > > Thanks, > > Patrick Sheffield > Sheffield Softworks > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Quartzcomposer-dev mailing list (Quartzcomposer-dev@lists.apple.com) > Help/Unsubscribe/Update your Subscription: > http://lists.apple.com/mailman/options/quartzcomposer-dev/kingluma%40comcast.net > > This email sent to kingl...@comcast.net _______________________________________________ Do not post admin requests to the list. They will be ignored. Quartzcomposer-dev mailing list (Quartzcomposer-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/quartzcomposer-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
