in praise of RawTherapee, "Amaze" demosaicing algorithm

Started Jun 10, 2011 | Discussions thread
RussellInCincinnati
Senior MemberPosts: 3,194
Like?
think you're getting the "why use anything else" type idea
In reply to boardsy, Jun 15, 2011

Boardsy: How/where do you set the "maximum 5 passes of false color suppression"? [in RT Raw Therapee with Amaze demosaicing]

Well, in RT version 3.0b1.42 (which you may notice I was already quite comfortable with over 40 years ago):

Boardsy: RT's "RL Deconvolution" is an either/or option with it's unsharp mask

Yes. You can either choose under the "Detail" topic to have no sharpening, or have unsharp mask sharpening with a bunch of parameters that have never looked at (because am not using), or you can choose RL Deconvolution. Said Deconvolution default parameters work so well, that haven't yet looked at any of its many options either. With the defaults, have noticed both much better sharpness , and (how could this be, must have something to do with the overall settings of RT that I haven't messed with or understood yet) less noise than with ADR demosaicing in my Picture Window Pro raw converter.

By the way this is not to denigrate PWpro (or any other ADR algorithm photo editor), which is still an important component of my workflow for every single picture. And e.g. am expecting to see the Amaze algorithm make its way into all photo editors eventually.

Boardsy:

[RL Deconvolution mild sharpening] which seems to have done a slightly better job here, right?

Ah, fun topic, that for some reason none of my family or friends care to discuss at any length.

RL Deconvolution, when used with the RT default settings, seems to just sharpen the image with very little "haloing" or exaggerating of fine detail edges. It just makes a dark/light edge crisper, without actually boosting up the light edge with a fine white line, and darkening the dark edge, the way unsharp mask does.

So you can run RT as my sample images showed, with just RL deconvolution, and have a pretty sharp (well sort of subtly sharp) image. In the full resolution .TIFF master output. My suggestion is to edit that TIFF image, and resize it for some certain purpose, then apply the ideal-strength, standard unsharp mask to that resized photo to make a final print.

The relevant point here is that if you ask for unsharp masking of the first master image to come out of RT, there will a bit of haloing that makes the master not so ideal for further unsharp mask for some final size and purpose.

Whereas the RL Deconvolution sharpening is subtle enough that it does not interfere with later unsharp masking, a pleasant situation indeed.

Put more shortly, RL Deconvolution can sharpen a picture more without producing hard-to-manage artifacts than unsharp masking can. Maybe unsharp masking can make an ultimately sharper looking photo, but if it did so (say on your max res master copy) you sure wouldn't be able to then resize that photo and/or do more sharpening on it.

This all started with looking for moire suppression, was not looking for more detail. But after just a few days, am not sure why anyone would want to develop raw files with a lesser algorithm, once you know about RawTherapee with Amaze and RL Deconvolution. Unless time is of the essence in your workflow. Nice suggestion, Pictus.

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