Re: [Gimp-developer] Finding out what happens when compositing layers
On 09/16/2011 09:31 PM, 丰 wrote: I came across this quite some time ago: http://www.simpelfilter.de/en/basics/mixmods.html That's wonderful! Even mentions GIMP a bit. Patrick ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Finding out what happens when compositing layers
On 09/16/2011 02:20 AM, David Gowers (kampu) wrote: In GEGL, the layer mode code is autogenerated from formula strings -- see operations/generated/math.rb The opacity behaviour is not documented there, but my understanding is that the alpha of the underlying composite is preserved, and opacity only effects how much of the layer's COLOR channels are applied (per the standard blending formula). On Fri, Sep 16, 2011 at 7:09 AM, Ofnuts ofn...@laposte.net mailto:ofn...@laposte.net wrote: I'll trying to find out what happens when a layer is in subtract mode with a global opacity not one or zero (i.e. what computations are done with the pixels values of the composite image of the layers below, the pixel values of the layer, and the general opacity). I have a git extract of the Gimp source code (and of gegl babl) but got lost... Can someone help? Well, I know that in Normal mode, I have in each RGB channel: Composite=Over*alpha+Under(1-alpha) (assuming Under is fully opaque), but in Subtract mode, I would have several possibilities Composite=Under(1-alpha)-Over*alpha or Composite=Under(1-alpha)+(1-Over)*alpha or Composite=Under(1-alpha)+(1-Over*alpha) and $deity knows what else. math.rb isn't taking the opacity in account (but is an interesting read...) Thx. ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Finding out what happens when compositing layers
On Sat, Sep 17, 2011 at 8:36 AM, Ofnuts ofn...@laposte.net wrote: ** On 09/16/2011 02:20 AM, David Gowers (kampu) wrote: In GEGL, the layer mode code is autogenerated from formula strings -- see operations/generated/math.rb The opacity behaviour is not documented there, but my understanding is that the alpha of the underlying composite is preserved, and opacity only effects how much of the layer's COLOR channels are applied (per the standard blending formula). On Fri, Sep 16, 2011 at 7:09 AM, Ofnuts ofn...@laposte.net wrote: I'll trying to find out what happens when a layer is in subtract mode with a global opacity not one or zero (i.e. what computations are done with the pixels values of the composite image of the layers below, the pixel values of the layer, and the general opacity). I have a git extract of the Gimp source code (and of gegl babl) but got lost... Can someone help? Well, I know that in Normal mode, I have in each RGB channel: Composite=Over*alpha+Under(1-alpha) (assuming Under is fully opaque), but in Subtract mode, I would have several possibilities No, you just subtract Over from Under with no multiplication, then you perform a RGB (not RGBA) Composite of the result and Under, to produce the final composite. ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Finding out what happens when compositing layers
I came across this quite some time ago: http://www.simpelfilter.de/en/basics/mixmods.html -- 2.6.32.26-175.fc12.x86_64 ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Finding out what happens when compositing layers
I came across this quite some time ago: http://www.simpelfilter.de/en/basics/mixmods.html PS: I thought I had type in my word before I send the mail. I did not know what had happened. Sorry to everybody for the spam and wish this mail is all right. -- 2.6.32.26-175.fc12.x86_64 ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
Re: [Gimp-developer] Finding out what happens when compositing layers
In GEGL, the layer mode code is autogenerated from formula strings -- see operations/generated/math.rb The opacity behaviour is not documented there, but my understanding is that the alpha of the underlying composite is preserved, and opacity only effects how much of the layer's COLOR channels are applied (per the standard blending formula). On Fri, Sep 16, 2011 at 7:09 AM, Ofnuts ofn...@laposte.net wrote: I'll trying to find out what happens when a layer is in subtract mode with a global opacity not one or zero (i.e. what computations are done with the pixels values of the composite image of the layers below, the pixel values of the layer, and the general opacity). I have a git extract of the Gimp source code (and of gegl babl) but got lost... Can someone help? ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
