Well, if you need forensics methods digitally enhanced to make a diff picture legible, that’s my ground truth for “similar performance”.
@heckflosse Can you tell me which of these images is significantly different to your eyes? And which two are identical? At 100% zoom please 
Demosaic_try.zip (10.7 MB)
Edit: and for 10 bonus points, which image belongs to which demosaicing method.
Why should I do this (waste of time) ? You know that there are differences between outputs of different demosaicers. Do I really need to show examples? Then please provide a raw file. Then I will show the differences. Tiff (or png) files are not even worth a look, sorry 
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What are they for?
@heckflosse Please take note of the wink, it wasn’t meant too seriously. Both you and Aurelien are correct. At pixel peeping levels there are significant differences between algorithms which may get blown up due to other processing. At 100% zoom level and using a picture taken in ‘nice conditions’, the differences are almost non-existent and certainly not bothersome.
My zip contains an illustration to that point for anyone who’s interested. Look at 100% zoom and tell me which differences you see, then look at 400% zoom and spot the differences.
Interesting, thanks. I suppose these are simple crops from the demosaics, not resized? I hope you will say what seven methods were used.
With a quick script, I use ImageMagick to loop through each pair of images and find the largest RMSE difference. This is between images 1 and 4, with RMSE 0.011 on a scale of 0 to 1, so 1.1%. As a rule of thumb, 1% is the threshold at which I can just see that two ordinary photos are different, when the differences are evenly spread through the images.
At first glance, I can’t see differences between 1 and 4. But ImageMagick (or anything similar) can point out where the differences are.
magick Demosaic-1.png Demosaic-4.png -compose Difference -composite -auto-level demosaic-diff.png
Guided by this, I know where to look. And the differences are obvious, even at merely 100%.
Thanks, the tip of the high brightness curve helped make the naked eye differences even clearer.
So, I use a ‘half’ demosaic for my proofs, as it’s quick and looks fine when downsized to 800x600. For clients that want full resolution, I’d produce a rendition that used one of @heckflosse’s wonderful tools courtesy librtprocess. Haven’t had a client in at least 30 years, however… 
I’m also using half to process spectrum captures for SSF profiles; need RGB triplets to calculate channel averages down each image column, and half doesn’t change the original R and B captures, and only does an average of G1 and G2 for G. Need as little change as possible for the downstream processing…
@snibgo There are seven files, two of them use RCD (so should be identical), one is AMaZE, one is DCB, one is IGV, one is LMMSE and one is Fast. All options as named in RawTherapee.
There are no other adjustments to the image, except for a little increase in exposure, contrast and saturation - otherwise, things looked too dull.
Why not? Downsizing that much using quarter demosaic (binning) should be good enough 
Well, why using modern highres Nikon Cams then?
of @heckflosse’s wonderful tools courtesy librtprocess
Thanks, but not olny mine, also @CarVac and others were involved.
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Thanks. 3 and 7 are identical, so they are RCD. Which ones are AMaZE, DCB, IGV, LMMSE and Fast?
I will also add that while differences may not be visible immediately after demosiac, the differences can be much more pronounced after processing - particularly sharpening. (At least this is true for X-Trans images)
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Ok, I’ll bite…
4 is clearly “fast”, and it is significantly worse than the others. 3 and 7 are identical, so they must be RCD. From here, I’d guess 6 and 5 are Amaze and DCB (or the other way round), whereas 1 and 2 are IGV and LMMSE (or perhaps the other way round).
How far off am I? 
1 and 2 look very close to me, with 1 seeming slightly better. What’s your opinion?
My opinion: 1 and 2 look “crisper” than the others, but that’s because the picture has no sharpening applied. In fact, 1 and 2 have (according to my eye, I might be totally off here – but it would be nice to know 
some amount of false detail that is typical of IGV and/or LMMSE demosaicing, which were designed for noisy images. Here’s an example of RCD vs IGV (without sharpening):
I agree that in general the differences are minor, but it’s good to have a choice for dealing with more difficult situations…
I think you’re going to need shots of a resolution-sort of target. Something white, with lines…
depends on what you are interested in… there are clearly visible artifacts in one of the pictures above, if you know where to look. E.g.:
I find that capture sharpening can make these artifacts clearer. In fact, in one PlayRaw, I had to turn off CS because it was revealing them (maze patterns) in an unpleasant way.
