Maniphest T71586

RGB values wrong calculated/displayed (ignoring Color Management)
Closed, Archived
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Assigned To
Brecht Van Lommel (brecht)
Authored By
Michael Klein (Renderbricks)
Nov 14 2019, 9:40 PM
Tags
  • BF Blender
  • User Interface
Subscribers
Brecht Van Lommel (brecht)
Germano Cavalcante (mano-wii)
Michael Klein (Renderbricks)
ogierm
Steffen Dünner (SteffenD)

Description

System Information
Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: GeForce GTX 1060/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.20

Blender Version
Broken: version: 2.81 (sub 16), branch: master, commit date: 2019-11-13 16:25, hash: rB9bd0d8b5505a
Worked: (optional)

Short description of error
The RGB values will be displayed wrong. HSV and HEX are correct. The resulting color is correct.
The wrong decimal numbers seem to be a result by not considering the Color Management.

Exact steps for others to reproduce the error

  • Add RGB-node in compositor
  • Use Color example: 678F8F
  • Results

BLENDER

R: 0.136
G: 0.275
B: 0.275

RGB is wrong.

H: 0.500 (180°)
S: 0.280
V: 0.561

HSV is correct.
Output color on screen is correct.

Correct result in Maya:
R: 0.404
G: 0.561
B: 0.561

Correc result in Photoshop:
H: 180°
S: 28
B: 56

R: 103
G: 143
B: 143

In the attached picture you'll from left to right:
Blender Colors - Maya Colors (Color Management ON) - Maya Colors (Color Management OFF)

Related Objects

Mentioned Here
rBa7b3d58066a1: Fix T58014, T58650: issues with hex color and Filmic view transform.

Event Timeline

Michael Klein (Renderbricks) created this task.Nov 14 2019, 9:40 PM
Michael Klein (Renderbricks) updated the task description.
Michael Klein (Renderbricks) renamed this task from RGB values wrong calculated (ignoring Color Management) to RGB values wrong calculated/displayed (ignoring Color Management).Nov 14 2019, 9:43 PM
Michael Klein (Renderbricks) updated the task description.
Michael Klein (Renderbricks) updated the task description.Nov 14 2019, 9:45 PM
Michael Klein (Renderbricks) updated the task description.Nov 14 2019, 9:48 PM
Steffen Dünner (SteffenD) added a subscriber: Steffen Dünner (SteffenD).Nov 15 2019, 12:21 PM
ogierm added a subscriber: ogierm.Nov 15 2019, 11:35 PM
Germano Cavalcante (mano-wii) added a project: User Interface.Nov 20 2019, 11:21 PM
Germano Cavalcante (mano-wii) added subscribers: Brecht Van Lommel (brecht), Germano Cavalcante (mano-wii).

It seems that there really is an inconsistency between the other applications and Blender.
I used this site to check the values: https://www.rgbtohex.net/hextorgb/

Looking at the code, I found that the rgb value changes in this line:
https://developer.blender.org/diffusion/B/browse/master/source/blender/editors/interface/interface_region_color_picker.c$307

@Brecht Van Lommel (brecht), you have worked in this area before (rBa7b3d580), do you know why this happens?

Brecht Van Lommel (brecht) changed the task status from Unknown Status to Unknown Status.EditedNov 20 2019, 11:34 PM
Brecht Van Lommel (brecht) claimed this task.

By design, hex and HSV are sRGB, and RGB is scene linear.
https://docs.blender.org/manual/en/dev/interface/controls/templates/color_picker.html

Michael Klein (Renderbricks) added a comment.EditedNov 21 2019, 12:47 AM
In T71586#813990, @Brecht Van Lommel (brecht) wrote:

By design, hex and HSV are sRGB, and RGB is scene linear.
https://docs.blender.org/manual/en/dev/interface/controls/templates/color_picker.html

I assume RGB should also be sRGB and maybe adding a button to turn linear on/off. Otherwise it's totally confusing because the general RGB sliders of all programs are all using sRGB values. It doesn't make sense that V 0.5 is not RGB 0.5 0.5 0.5.

Michael Klein (Renderbricks) added a comment.EditedNov 21 2019, 4:22 PM

I found out that Maya is using linear for RGB and HSV. Maya just shows it different. Attached you see the screenshot of the sliders with linear Color Management on and off. In Blender you'll see it at the vertical greyscale bar.

Michael Klein (Renderbricks) added a comment.EditedNov 21 2019, 4:52 PM

To clarify:
Maya is generally set to linear for RGB and HSV. Maya is not supporting HEX.

I can't copy RGB/HSV values from PSD to Maya. I can preview the PSD sRGB color when I turn Color Management off but I still have the linear result. A workaround is to split the screen and use a color picker in Maya and pick the PSD color.

But I can copy HEX from PSD to Blender. The linear RGB numbers can be copied correctly to Maya.

So the Blender method seems to be good/better. Color Management is always confusing.