Ross.
IMAGE_QUALITY does not any matters depending on Color displaying of photos in your script.
IMAGE_QUALITY affects on pixel structure only.
The general reason is that your devs use very old PHP library - WideImage whose the last release 11.02.19 was on February 19th, 2011 (it's unbelievable!)
And WideImage using GD library only, not ImageMagic. But GD does NOT support ICC color Profiles, especially Adobe RGB (1998) that professional photographers really frequently use.
And thus our photos look much dimmer than their original right after full uploading not temporary!..
We offer you to change that very old library WideImage (not supported anymore) on some new popular image manipulation PHP library that use and GD and ImageMagic libs by choice of Oxwall script site admin in main settings!
And I post 2 pics BEFORE and AFTER uploading once again (open full size!). Please look very carefully, the COLOR difference (not pixel quality) is obvious: