Color picker and gamma

[John_Do]

Hello,

I browsed The Foundry forums about this topic but I'm struggling again with the good old gamma subject. But this time it's not about textures but color picker.

I'm setting up a scene for quick product visualisation and have imported a Macbeth Color chart for proper colors and levels calibration. Everything is fine except the fact that I can't match the chart's colors if I I enter similar values directly in Modo color swatch. However, I can match the colors if I use the system color picker ( by clicking on the color square in Modo Color Picker window ). See below for a more visual explanation of my issue.



So, the subject has been discussed many time on TF forums but I still can't figure which color picker I can trust to have correct colors values, "physically correct values", especially in the extremes, like max white values, max black values ?

[vladimir.nedev]

Which color picker dialog is the correct one, depends on where you got the color values from.

MODO's own color picker expects the values you enter to be in the linear color space.
So, if you have some measured albedo values for various materials, like the ones listed here : https://en.wikipedia.org/wiki/Albedo#Terrestrial_albedo
they are most likely in the linear color space, so you just enter them directly in the MODO color picker.

The system color picker on the other hand, expects the values to be gamma corrected.
If you have colors sampled from a texture or Photoshop, then you can directly enter those in there.

There is a simple kit that adds a command entry in the context menu which pops up after right clicking on a channel.
The commands lets you convert the color value between linear and 2.2 gamma corrected.
So, if you have a color value from Photoshop, you enter it in MODO's color picker, and then right click on the color and choose "Apply 2.2 gamma".
This basically converts the gamma corrected color to linear, as MODO expects it.

Here is an explanation from The Foundry guys (contains a link to the mentioned kit):
http://community.thefoundry.co.uk/di...1691&p=1016205

The values in your chart don't seem to be neither linear, nor 2.2 gamma corrected though.

Greetings,
Vladimir Nedev

[John_Do]

Hi Vladimir,

Thank you for the link and the explanation, I didn't see this kit during my research, very useful and makes the Modo color picker really usable now.