I'm still confused...
The GMK Honeywell Render for example:
Doesn't look anything like this to me:
Plum Render:
Plum GMK Render:
Plum:
One of the things you have to keep in mind, especially with tans, is the spectrum of your light is going to have a tremendous impact on how something looks.
Hydro GMK Render:
Hydro Render:
Hydro:
To my eyes the GMK renders are ALWAYS less accurate.
For hydro the blues are undersaturated. The gray is oversaturated.
My best guess is GMK is rendering the images in something other than normal RGB/YUV. An extended color space or something, and then not doing a good converstion. I wouldn't be surprised at all if there were some way to filter the GMK renders to make them all accurate (with the same filter) because to me, they all seem flawed in the same way.