So currently I have PNG exporting with a downsizing from 4K res to 720p res, I did use the SSIM downscaler with the Spline64 kernel, however the gamma correction is not turned on in the downscaler. I'm getting weird colour shifts which heavily saturate the entire picture and also basically crushes the blacks.
https://ibb.co/DV8FF74
https://ibb.co/khKDJvG
The photos are attatched
Wild guess: might be an issue with luma range (TV vs PC) and color matrix settings on in/export,...
First of all, as Selur suggested check if Full vs Limited Range Levels are correct. Images use Full Range, Video use Limited Range.
Also in short - it all depends of your video player and image viewer. Common image sRGB gamma is different from common video Rec709 gamma. In addition to Full vs Limited data range, problem could be due video tags for video stream and container (some video players may read but some may ignore), newer color managed video players and OSes vs legacy non color managed. Windows vs macOS color management, different color management in different web browsers. So it will always look different and there is no way to make it look the same. This is a huge global and historical industry problem and it have no any universal fix.
Here is a thread with some examples
https://forum.blackmagicdesign.com/viewt...1&t=101253