They also mention it’s not free. That would be ok. Just say your test is image quality of free image formats.
But that statement just undermined the trust I had in the author up to that point.
I should include that under "Takeaway," I do say that " ... this is a non-scientific test," & it shouldn't be considered objective despite the use of metrics. While I find SSIMULACRA2 correlates very well with what my eyes see with these images & most other images, 27 landscape/architecture images aren't enough to draw any objective conclusions here & I'd need to do more testing in the future to produce research-quality work.
I appreciate what you did. Your article is far above a simple “I looked at five pictures and decided this one was the best“ kind of comparison that you sometimes see. You clearly tried to do a good and fair job with your contenders.
The results were interesting to see. This isn’t an area I spent time in so I really didn’t know what to expect going in other than thinking there must be something better than the venerable JPEG.