Quadro colors vs Geforce colors in PPM file format rasterization by GIMP?

I posted the following on the VMD mailing list but did not get any replies. Was wondering if any nvidia gurus understand what is going on here?

“Creating a ppm file using tachyon optiX in visual molecular dynamics, or VMD, on the gpu renders beautifully on my laptop with a Quadro K5100M gpu. Opening the ppm file in GIMP and converting to png after cropping and whatnot, works great. If the ppm file is moved to a different workstation with a lesser gpu, such as Geforce 950, then opening in GIMP shows dull colors. I’ve been reading about the ppm image format to try and get a handle on what is going on at http://netpbm.sourceforge.net/doc/ppm.html. But, I was wondering if other people have experience with this problem and have solved it? We’d like to remote render with tachyonOptiX, in VMD for publication images but need to solve this problem first. Everyone wants to use my laptop to render and convert ppm to png… It is like the available color space is different and graphic card dependent when using a ppm file as the source. A rasterized file format doesn’t produce this effect.”

I appreciate your thoughts.

Rather sounds like you’re applying an inappropriate color profile on import. Compare the gimp settings regarding color management.
For display, check what icc profile the desktop has set.