Re: [Gimp-developer] 10-bit display color depth support (30-bit, deep color)

[Magnus Larsson <k magnus larsson bahnhof se>]

A fix in message

I am using EIZO Color Edge CG279X monitor and the quoted message was 
from Nov 2020.

Magnus

On 12/5/21 12:43 PM, Magnus Larsson wrote:
> Hello gimp-developer-list,
>
> In this mail to gimp-user 
> https://mail.gnome.org/archives/gimp-user-list/2020-November/msg00002.html, 
> from /From/: LKH about 10-bit display color depth support (30-bit, 
> deep color) the discussion (from last year Nov 2021) end with:
>
> "
>
>
>  Re: [Gimp-user] 10-bit display color depth support (30-bit, deep color)
>
> ------------------------------------------------------------------------
>
>  * /From/: LKH <lkhgraf protonmail com>
>  * /To/: Liam R E Quin <liam holoweb net>, "gimp-user-list gnome org"
>    <gimp-user-list gnome org>
>  * /Subject/: Re: [Gimp-user] 10-bit display color depth support
>    (30-bit, deep color)
>  * /Date/: Sun, 15 Nov 2020 06:19:32 +0000
>
> ------------------------------------------------------------------------
>
> I am still experiencing banding with a gradient made from scratch in 
> GIMP 2.99 in 32-bit floating point mode
> on X11 when xdpyinfo and xwininfo say the window is 30-bit. If 
> dithering is off the banding is obvious. I
> believe 16-bit support for TIFF is in GIMP anyway because it says it 
> is in 16-bit mode after loading it.
>
> I have tested Adobe Photoshop CC on both Windows and macOS and the 
> monitor does successfully display in 30
> bit. No amount of zooming in on the test gradient produces banding in 
> those cases.
>
> "
>
> Issue:
> I am seeing the same thing as user LKH, that is GIMP does not render 
> 30-bit, deep color on my Linux system. (I do not have Adobe Photoshop 
> on Windows, so this I have not tested).
>
> I understand many conditions have to be fulfilled:
> 1) Application can render: I am using GIMP_2_99_8-110-g44f6ee36fe 
> compiled from git source.
>
> 2) OS can render: I am using Debian 11 with X11 with 30 bit depth 
> enabled (not Wayland):
> xwininfo -root | grep Depth =>   Depth: 30
> glxinfo | grep "direct rendering" => direct rendering: Yes
>
> 3) I have an NVIDIA Quadro RTX 4000 GPU with NVIDIA drivers that 
> support 30 bits and Nvidia Xserver Setting app report back 30 bits 
> when checked
>
> 4) I am using EIZO GLX 2790X wide gamut monitor and monitor reports 
> that it is operating in 10 bits when queried: EIZO monitor | Signal => 
> Full Range, RGB 10 bit
>
> 5) A set of test files which actually has 10 bit or more raster and 
> GIMP in 16 bit mode: GIMP | Image | Encoding => 16 bit
>
> I can still see no difference between an 8 bit gradient (in 8 bits) 
> and a 16-bit gradient (in 16 bits).
>
> I use these test images (I have used other test files as well. Same 
> result. No 10 bit gradation is rendered in GIMP display):
> https://www.eizo-apac.com/support-service/tech-library/monitor-test
> 16_bit_TIFF: 
> https://www.eizo-apac.com/static/uploads/files/16bitgradation-wfuncyaztzod.tif
> 8_bit_gradient: 
> https://www.eizo-apac.com/static/uploads/files/8bitgradation-wfqfukzeuago.tif
>
> What do you think?
>
> I respect the complexity of 1-5 above, but feedback in gimp-user list 
> refered to above, seem to indicate that GIMP can use 30-bit visuals, 
> at least GIMP 2.99-x.
>
> Best regards,
>
> Magnus Larsson
>
>
>
>
>
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