is Agx working as expected? #111453

New Issue

Closed

opened 2023-08-24 01:34:40 +02:00 by Nahuel Belich · 5 comments

Nahuel Belich commented

2023-08-24 01:34:40 +02:00

System Information
Operating system: Linux-6.2.0-26-generic-x86_64-with-glibc2.35 64 Bits, X11 UI
Graphics card: NVIDIA GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 525.125.06

Blender Version
Broken: version: 4.0.0 Alpha, branch: main, commit date: 2023-08-23 19:52, hash: 7c2dc5183d03
Worked: (newest version of Blender that worked as expected)

Short description of error
In this extreme example testing against filmic works better with the blue/violet overexposed colors but it does something weird with reds.

Filmic	AgX (notice the red tile on the right )

Also it looks weird because the Grayscale look, looks like this, that red tile has almost 0 value, compared with the image before.

Exact steps for others to reproduce the error
AGX text.blend

**System Information** Operating system: Linux-6.2.0-26-generic-x86_64-with-glibc2.35 64 Bits, X11 UI Graphics card: NVIDIA GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 525.125.06 **Blender Version** Broken: version: 4.0.0 Alpha, branch: main, commit date: 2023-08-23 19:52, hash: `7c2dc5183d03` Worked: (newest version of Blender that worked as expected) **Short description of error** In this extreme example testing against filmic works better with the blue/violet overexposed colors but it does something weird with reds. | Filmic | AgX (notice the red tile on the right ) | | -- | -- | | ![image](/attachments/7f98f4bd-4a3f-482c-acff-7169bbed1d3d) | ![image](/attachments/d2d0d8a4-2506-4d0b-acb4-3b16eae79fa1) | Also it looks weird because the Grayscale look, looks like this, that red tile has almost 0 value, compared with the image before. ![image](/attachments/a9f71226-b95b-40c7-9db5-650a2df192b2) **Exact steps for others to reproduce the error** [AGX text.blend](/attachments/ef78d71d-e37c-455b-b95b-df9e81a7c8e1)

502 KiB

AGX text.blend

915 KiB

822 KiB

745 KiB

Nahuel Belich added the

labels 2023-08-24 01:34:41 +02:00

Pratik Borhade commented

2023-08-24 08:18:42 +02:00

Member

Hi, thanks for the report. Can confirm.
cc @Eary

Hi, thanks for the report. Can confirm. cc @Eary

Pratik Borhade added

Render Pipeline

and removed

labels 2023-08-24 08:19:09 +02:00

Zijun Zhou commented

2023-08-24 09:02:49 +02:00

Contributor

It seems you applied extreme power curve (that confusing "Gamma" setting is actually an inverse power law curve) after view transform. It's completely normal for view transforms to show this kind of breakage under this kind of setting. ARRI Reveal (ARRI Alexa 35's image formation protocol) for example:

This is simply the power function breaking the sRGB display encoding showing some weird H-K effect due to the per-channel nature of the power curve.

I would say this is not a bug.

It seems you applied extreme power curve (that confusing "Gamma" setting is actually an inverse power law curve) after view transform. It's completely normal for view transforms to show this kind of breakage under this kind of setting. ARRI Reveal (ARRI Alexa 35's image formation protocol) for example: ![image](/attachments/85e73c20-9b40-4901-b1ab-3d3fd5556210) This is simply the power function breaking the sRGB display encoding showing some weird [H-K effect](https://en.wikipedia.org/wiki/Helmholtz%E2%80%93Kohlrausch_effect) due to the per-channel nature of the power curve. I would say this is not a bug.

938 KiB

Nahuel Belich commented

2023-08-24 10:00:34 +02:00

Author

i see, yes changing the Display device to other than sRgb works fine, im not sure how safe its to change de Display device using old led monitors is, but seems to work to put the color in safe range.
Something new to get used to.

i see, yes changing the Display device to other than sRgb works fine, im not sure how safe its to change de Display device using old led monitors is, but seems to work to put the color in safe range. Something new to get used to. <video src="/attachments/5201cea6-085d-47f3-975e-5993bc3378ee" title="Screencast from 24-08-23 04:56:18.mp4" controls></video>

Screencast from 24-08-23 04:56:18.mp4

724 KiB

Zijun Zhou commented

2023-08-24 10:06:39 +02:00

Contributor

You shouldn't change the display device to something that is not your monitor hardware that you are staring at right now.

It triggers H-K effect because the extreme per-channel power curve crushes the gradients to an extreme. So just don't use that kind of extreme power curve setting. 1/1.35 is what the Punchy look is approximating, I would advice not going too further from that.

The point is, the extreme Gamma setting applied after the view transform is what's at fault here, not AgX. So not a bug here.

You shouldn't change the display device to something that is not your monitor hardware that you are staring at right now. It triggers [H-K effect](https://en.wikipedia.org/wiki/Helmholtz%E2%80%93Kohlrausch_effect) because the extreme per-channel power curve crushes the gradients to an extreme. So just don't use that kind of extreme power curve setting. `1/1.35` is what the `Punchy` look is approximating, I would advice not going too further from that. The point is, the extreme `Gamma` setting applied after the view transform is what's at fault here, not AgX. So not a bug here.

YimingWu commented

2023-08-25 04:54:21 +02:00

Member

I guess we can close this report for now.

I guess we can close this report for now.

YimingWu closed this issue

2023-08-25 04:54:24 +02:00

Blender Bot added

and removed

labels 2023-08-25 04:54:26 +02:00

Sign in to join this conversation.

No Label

Animation & Rigging

Asset Browser Project Overview

Automated Testing

Blender Asset Bundle

Dependency Graph

Development Management

EEVEE & Viewport

Images & Movies

Motion Tracking

Nodes & Physics

Pipeline, Assets & IO

Platforms, Builds & Tests

Render & Cycles

Render Pipeline

Sculpt, Paint & Texture

Video Sequencer

Virtual Reality

Blender 2.8 Project

Milestone 1: Basic, Local Asset Browser

Good First Issue

Animation & Rigging

Development Management

EEVEE & Viewport

Nodes & Physics

Pipeline, Assets & IO

Platforms, Builds & Tests

Render & Cycles

Sculpt, Paint & Texture

Needs Info from Developers

Needs Information from User

No Milestone

No project

No Assignees

4 Participants

Notifications

Due Date

The due date is invalid or out of range. Please use the format 'yyyy-mm-dd'.

No due date set.

Dependencies

No dependencies set.

Reference: blender/blender#111453

No description provided.