Thank you Len @lphilpot and Jacques @Jade_NL
I have recent version (5.8) of RawTherapee and I downloaded the Canon 90D [canon_eos90d_matrix-colprof.icc] file that I apply manually to each picture before I started with the post-processing.
I guess, I’ll first “learn” RawTherapee" from RawPedia. Since I switched from CR2 to CR3, I’ve been struggling with the post-processing of my images. I have been using RawTherapee with proper homework. So I guess, it’s time to learn 
@Jade_NL, @tanmayj316 my apologies for the miscue on the profile. I use a Canon T8i (850D) and I’ve found no profile for it bundled with RT. I’m running a dev build appimage, so where would I look for that? Or do I need to build RT instead?
At any rate, Adobe’s 850D profile is good enough as a starting point for me now, but if I can cut external dependencies, as it were, I’d like to.
Thanks.
As far as I can tell, looking at GitHub and searching my own machine, there is no Canon T8i/850D DCP profile created by the RawTherapee team (or RT User) as of yet.
If you are able and willing you can create the DCP profile yourself. Or hand the specially shot RAWs over to the RT team so they can create a camera specific DCP file make it part of RT. Both ways are mentioned here: How to Create DCP Color Profiles.
Glen what command did you use to generate that patch error report…Thx as always…
dcamprof produces the data with -r. I wrote a script to take patch_errors.txt and sort it by DE, also I modfied each line to only include RGB values. A bit of sed and awk:
#!/bin/bash
sort -nk18 patch-errors.txt |sed 's/ DE / foo /' |sed -r 's/RGB.+foo/DE/'
Edit: Oops, no awk… 
ART has an 800D…would that be a close enough model to be useful…I didn’t see this in my version of RT which ins’t too old maybe one month at the most…
CANON EOS 800D.dcp (63.8 KB)
Yeah, i saw the 800D profile in ART. I’ll compare it against the Adobe 850D and see what I think. I’m not expecting finished perfection from the get-go, just a (for me) better starting point than flat neutral.
Thanks.