ART vs RAWtherapee Highlight reconstruction issues maybe

attach below is a comparison between ART and rawtherapee it seems that there is some artifact in ART when using the same highlight reconstruction method. I don’t know if it’s a bug or by design hope someone could shed some light on it. the artifact appears at the edge of the flame as red blocks. it seems less in rawtherapee.

Hello, do you see those artefacts in Art as well when choosing Blend as highlight reconstruction method? Under certain circumstances the used method may be off (bad result I mean) or good. If I remember well, this highlight reconstruction is based on an educated guess, as the original white pixels are clipped to max.

Can you share the raw and the sidecars (arp and pp3)? Thanks!

here is the raw file and the RAW, arp and pp3 files. thanks @agriggio for looking into this.
@paulmatth yes i did tried it with blend the artifact will disappear but the color propagation looks better

20160123-0182.orf (16.7 MB)
20160123-0182.orf.arp (11.1 KB)
20160123-0182.orf.pp3 (14.8 KB)

Thanks for the files. There are a number of things going on here:

  1. you are using two different demosaicing methods (RCD in ART vs Amaze in RT)
  2. while in general RLD sharpening in ART can be considered comparable to capture sharpening in RT, the latter has some logic to avoid introducing artifacts due to sharpening edges along transition areas between clipped and non clipped parts of the image
  3. [less critical, but still accounts for some visual differences] the tone curves are different (the automatching logic in ART tries to generate simpler curves, trading accuracy for robustness)

All of the above contribute to the differences. You can get rid of the artifacts in ART by:

  1. change demosaicing from RCD to Amaze
  2. turn off sharpening, or increase “reconstruction smoothness” in highlight recovery (e.g. set to 2). This is a parameter I just introduced, so you need to pull from the latest master version


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thanks for the amazing explanation.

is the reconstruction smoothness the same as blur when color propagation is selected

thanks again i will pull from the latest master and compile


i wanted to ask you whats the difference between the balance method and color propagation method for the highlight reconstruction

Balanced is a bit less aggressive in propagating colour (letting more pixels to go full white), which helps in avoiding artifacts sometimes – not always though, there’s no magic (that I know of at least)

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Thanks for the explanation