Question about pixelpipes


I’m a little confused about the pixelpipes. In the documentation only four pixelpipes are documented, but when I start darktable in opencl debug mode, I see five pixelpipes:

0.147102 [opencl_priorities] these are your device priorities:
0.147104 [opencl_priorities] 		image	preview	export	thumbs	preview2
0.147106 [opencl_priorities]		1	0	0	1	-1
0.147108 [opencl_priorities]		0	-1	1	0	0
0.147109 [opencl_priorities] show if opencl use is mandatory for a given pixelpipe:
0.147110 [opencl_priorities] 		image	preview	export	thumbs	preview2
0.147112 [opencl_priorities]		0	0	0	0	0

What are those preview pixelpipes exactly for?

Thanks! :slight_smile:

I think this is the second darkroom window, and effectively it’s not described in the opencl configuration help (probably because it was added latter than when most of that section was written).


Those are the small navigation windows normally shown on top left, allowing you to move around and set zoom levels:

another pixelpipe processes the preview image (navigation window)

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I’am sorry, but I’am still confused what the preview2 is for. There is no doubt on the preview (the old one). But preview2? The manual still doesn’t help here, see: opencl/multiple devices.

Could someone explain what exactly preview2 is for?

My understanding it that there are 5 “pixelpipes”, pp1/pp2/pp3/pp4/pp5:

  • pp1 is for the main image in darkroom
  • pp2 is for the navigation (preview) image in darkroom (top left corner)
  • pp3 is for exports
  • pp4 is for thumbnail processing
  • pp5 (not listed in the manual) is for the image on the second display in dual display mode

You can assign a specific and different GPU for each of these pixelpipes (you can do that in the darktablerc config file).

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