Some praise for RawTherapee features by Mark Metternich

Okay, this was… Interesting. And pretty much garbage.

Let me preface this by saying that I already was sceptical about anyone who claims RT has “the best” upsizing algo. But boy, after 10 minutes or so of the video I just had to stop watching to take in what is going on. Also, he starts of by saying this is an extremely short video… Well, 30 minutes isn’t particularly short. But hey, I’m commuting so I have time.

Content wise, there is too much unfounded opinion in this video. He claims the internet contains misleading and useless information about pretty much everything (algorithms, their quality, proper testing methods), but he does nothing to properly educate his audience. Instead, he just skips over these criticisms and continues by presenting his opinion as truth.
And then there are claims that a certain monitor pixel pitch is ideal for viewing detail? What the hell? No context whatsoever, no explanation either.

I mean, he doesn’t even acknowledge the fundamental issue with upsizing: creating information out of “nothing” and doing some smart interpolation. He also fails to mention sinc interpolation, which is technically the optimal solution (if I am not mistaken).

The he starts his RT explanation by highlighting a bug. Great start. His explanation of turning tools on is helpful, but calling it quirky is not. Then he mistakes post-process sharpening with capture sharpening, but mentioned deconvolution and bashes Adobe’s Detail slider, pretty much in the same sentence. Uhm, what should I take away from that?

Then it completely breaks down when he insists on changing the Working profile setting. He does not understand three things: that RT internally works with linear rgb data, that the working profile setting in 5.8 is not doing what is says, and that the sharpening algorithms in general should never, ever (edit: okay, maybe sometimes) be applied on nonlinear data to prevent haloing and artefacts (see the lengthy discussion here Quick question on RT Richardson–Lucy implementation for example).

He is also equating quality to processing time. Which really isn’t always the case, especially if you’re using RT on macOS with an M1 for which the software isn’t really optimized.

The final comparison part I just skipped. His claims about seeing more detail by pixel peeping at max zoom, while simultaneously intending to print the thing at 60 inches high makes zero logical sense. The viewing conditions are completely different, as is the perception of detail. Pixel differences do not tell you about that.

All in all, I’m happy this guy likes the (pretty generic) Lancsoz upsizing algorithm in RT. And he shoots great photos. But his knowledge of image processing and so on is severely compromised and should certainly not be taken as authorative imo.

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