[CREATE] Some questions about OpenRaster Format, Color and GEGL

[Wolthera]

On Mon, Jun 3, 2019 at 4:12 PM Jan-Peter Homann
<homann at colormanagement.de> wrote:
>
> Hi to all,
> It was nice to attend LGM2019 my first time and talk to a lot of LGM Developers and Designers. :-))
>
> I want to dive deeper in GEGL and the OpenRaster Format concerning color and have some questions:
>
> 1) Current state of the OpenRaster specifications:
> I found following site about the OpenRaster Specifications
> 1a) https://www.openraster.org/
> 1b) https://freedesktop.org/wiki/Specifications/OpenRaster/
>
> They have very similar content, but 1a seems to be most up to date version. Is this correct?

Yes. There's also an abandoned attempt to get the freedesktop version
onto github, but the maintainer dissapeared.

>
> 2) Whats about Color in OpenRaster ?
> I didn´t found any description about supported Colorspaces and the handling of color profiles in the OpenRaster Spec.
> So which colorspaces are supported in OpenRaster:
> RGB
> RGBA
> Gray
> LAB
> 1-Bit (Black and White)
> CMYK
> Spotcolor Channels / Multichannel Images

RGBA(sRGB). The only raster type supported right now is PNG. There
were some talks about cs support, but the previous maintainer
dissapeared before anything could be done.

>
> Does OpenRaster supports embedded ICC profiles?
>
> 3) GEGL and Color
> Pippin, did I understood you at LGM correct, that GEGL is able to use different ICC-profiles for chunks/nodes in the GEGL tree ?
> If yes, is it correct, that OpenRaster would not be an appropriate file format for such cases?
> or, If yes, do you provide an extension the the OpenRaster format?
> If not, this was probably a missunderstanding from my side...
>
> If yes, the complexity of interactions between colormanagement and blending modes will increase massively. Photoshop still avoids this complexity by allowing only one profile per document. If any new image with a differnt colorspace (e.g. CMYK instead of RGB) or different profile (e.g. sRGB instead of AdobeRGB) will be added to an document, all image colors will concerted to actual document colorspace.

Krita too uses per-node color spaces. What is more a concern here is
that the main layer format is PNG, and while there has been discussion
about supporting other types, this was never implemented.

>
> Best regards
> Jan-Peter
>
>
>
>
> --
> Homann colormanagement    tel: +49 30 611 075 18
> Jan-Peter Homann          mob: +49 171 54 70 358
> Herzbergstr. 55           www.colormanagement.de
> 10365 Berlin    mailto:homann at colormanagement.de
>
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We've now put everything on OpenRaster.org, which is hosted on the KDE
websites. What we should probably do is ask KDE sysadmin if we can
have a project for OpenRaster on the KDE gitlab. That way we can maybe
start moving forward by using issues as discussion.

-- 
Wolthera