[x3d-public] x3d-public Digest, Vol 173, Issue 79

[Andreas Plesch]

I found that Castle actually ignores embedded color profiles in
texture images in glTFs as required and sidesteps the problem by
generating new PixelTextures from these images.

This works in principle but is not practical for large textures which
today can have 4kx4k pixels, 16 * (10+1) MCharacters = 170MBytes as
PixelTexture.

I guess one could recompress these raw images to say png. If an X3D
optimizer could do that it might be a viable solution.

But a flag field to turn off color space conversion from embedded ICC
profiles would be more elegant and very useful for custom shaders
which expect consistent input.

-Andreas

> Date: Mon, 21 Aug 2023 01:22:59 +0200
> From: Holger Seelig <holger.seelig at yahoo.de>
> To: X3D <x3d-public at web3d.org>
> Subject: [x3d-public] Need for colorspaceConversion field in
>         ImageTexture
>
> There is still the problem that the issue of ICC color profiles is not addressed here, although it is an urgent issue. For people who have not yet dealt with this problem, it may seem like it is not important, but it is of interest to professional graphic designers.
>
> When it comes to texturing, there is nothing about ICC color profiles in the X3D spec:
>
> https://www.google.com/search?client=firefox-b-d&q=ICC+site%3Ahttps%3A%2F%2Fwww.web3d.org%2Fdocuments%2Fspecifications%2F19775-1%2FV4.0%2FPart01%2F
>
> But in glTF spec, they are very aware of that:
>
> > ... images SHOULD NOT contain ... ICC profiles. Such features, if present, MUST be ignored by client implementations.
>
> But we in X3D do, and the problem occurs if we want to try to convert glTF to X3D, which is possible and straightforward, but we need options to do this in the right way, and in a way everyone is satisfied.
>
> Best regards,
> Holger from LE

--
Andreas Plesch
Waltham, MA 02453