Strange results from DxO PhotoLab "Prime" noise reduction

[katastrofa]

I usually use "Prime" denoising in DxO PhotoLab for photos taken with high ISO, because it works better. Not in the case of one of my cats, though:

HQ denoising:




HQ (fast) algorithm

"Prime" denoising:



[ATTACH alt=""Prime" algorithm "]1812574[/ATTACH]
"Prime" algorithm

If you look at the tail end of the cat (bottom left of the photo), there is lots of luminance noise left by "Prime" algorithm, which is removed by the HQ algorithm. I never saw such an effect before. Is this something to be expected?

 

[Mystery member]

Fine looking cat. Burmese male?

Any more like that that you want to add to gallery?

 

[katastrofa]

Thanks! It's Oriental Shorthair this photo is not good, too much noise and cluttered background. I just wanted to find out about the noise reduction problem.

 

[Egregius V]

What are your noise reduction settings in PhotoLab? Knowing the other settings would help, too - but NR slider settings first. What I'm seeing in your cat photo is a lot of chroma noise, not just luminance noise - and some artifacts which I've also seen at high ISO with PRIME.

 

[CAcreeks]

Thanks! It's Oriental Shorthair this photo is not good, too much noise and cluttered background. I just wanted to find out about the noise reduction problem.

I thought DxO PRIME noise reduction was better than that. Maybe it needs a more specific camera profile for your EM1-ii, although ISO 4000 is high and bad results should be expected.

You could probably do a better job with manual controls for chroma noise reduction. If the ORF is available, I'd like to try with RawTherapee.

As for the tail, you are correct that it isn't any better with PRIME, though the rest of the image is better at 100%. However when downsampled to screen size (1200 pixels high) there is no apparent difference between the images.

P.S. Amazing cat!

 

[bent christian]

I can still see the chroma noise in the "HQ" denoising, it's just that the preset turned your image into a pile of mush, so it's not as noticeable. Don't use presets. What you want to do is up the chroma slider, lower any "details" slider and selectively sharpen (don't sharpen over everything).

 

[katastrofa]

Thank you He's very pleased with himself.

Here's the ORF file: https://www.dropbox.com/s/41qu9px4px90tyu/P1060025.ORF?dl=0

 

[CAcreeks]

Thank you He's very pleased with himself.

Here's the ORF file: https://www.dropbox.com/s/41qu9px4px90tyu/P1060025.ORF?dl=0

Thanks, that was fun! Sorry I am not very good with RawTherapee. The white door is too pink, I guess because I optimized for the brown cat. But it looks like chroma noise is reduced.




I chose most of the Denoise options, then reduced green in the cat's fur.

 

[katastrofa]

Thanks, you made one cat very happy

RawTherapee seems to be pretty good at denoising.

 

[Egregius V]

Thank you He's very pleased with himself.

Here's the ORF file: https://www.dropbox.com/s/41qu9px4px90tyu/P1060025.ORF?dl=0

I tried your RAW file - thanks for providing it. Turn on Moire removal in PhotoLab: it will take care of the remaining chroma noise and let you adjust PRIME for better control of the luminance noise.

(EDIT: there might be a rendering bug in PhotoLab: I've noticed that I sometimes have to click on a blank area of the filmstrip image selector and then reselect the RAW image I'm working on to get a correct display of the effects of lens sharpness, noise reduction, etc. For a while, the Luminance slider was having no effect at all - and then I did what I just described and it suddenly worked again.)

I am working on a similar issue with my own RAW files and am finding that RawTherapee and darktable handle noise reduction in a much less selective way than DxO. If there is moire or an unwanted pattern from poor demosaicing, noise reduction will handle these problems. PRIME (and occasionally HQ) cannot, but DxO's RGB noise reduction module will (when the file you're working on isn't RAW).

--
On Flickr: https://www.flickr.com/photos/revgv/

 

[katastrofa]

Luminance: 40

Chrominance: 100

Low freq: 75

Dead pixels: 24

Maze: 30

Moire: Off

 

[CAcreeks]

Luminance: 40

Chrominance: 100

Low freq: 75

Dead pixels: 24

Maze: 30

Moire: Off

Does Maze 30 mean to do a moderate amount of maze reduction? I found this DxO page about it ("removing Gr-Gb imbalance before demosaicing").

https://support.dxo.com/hc/en-us/articles/115015499368-What-is-maze-

Over on the Fuji X forum they talk frequently about Lightroom creating "maze" artifacts from X-Trans especially when over-sharpened. Over there I've never seen anything like the above, however.

 

[katastrofa]

Sliders in DxO PhotoLab are fro 0 to 100, or from -100 to 100 (except for some cases like exposure compensation).

 

[Egregius V]

Since PhotoLab came out and I learned what mazing is, I've been noticing it in some of my photos. For example:




uncorrectable maze artifacts in DxO PhotoLab

This is definitely from DxO's approach to demosaicing. PRIME - even with the Maze slider - can't do a thing about it. There's also some color fringing which DxO's Moire tool reduces. RawTherapee offers some demosaicing options which remove the maze; luminance and chroma noise reduction in RT and darktable are also effective. (I asked DxO about this yesterday and am awaiting their evaluation.)

--
On Flickr: https://www.flickr.com/photos/revgv/

 

[katastrofa]

Do you mean selectively sharpening with U-point tools?

 

[katastrofa]

Moire removal didn't help a lot, but upping "Dead pixels" to 87 did:

 

[CAcreeks]

Yes, good work! This is the best so far.

Moire removal didn't help a lot, but upping "Dead pixels" to 87 did:

 

[bent christian]

Do you mean selectively sharpening with U-point tools?

I meant with brushes or something similar. I don't know what U-point tools are. I don't use DxO. As a general rule, sharpening noise only makes it worse, particularly in an out of focus background. Subtlety sharpen only what is in focus and has been noise-reduced. I always reduce for the noisiest area of the photo. Reduce noise, then selectively sharpen.

 

[katastrofa]

The sequence "reduce, then sharpen" will lose data in the areas which have little noise, won't it?

 

[bent christian]

The sequence "reduce, then sharpen" will lose data in the areas which have little noise, won't it?

Data? No. An area that is in proper focus initially should not lose clarity to the point that it cannot be recovered after the fact, unless you are applying too much reduction. RAW data files, for example, already come out of the camera unsharp.

Noise reduction is a trade-off. Sharpening noise is always a bad idea. Reducing noise on and already sharpened image reduces clarity. The two practices. when done out of order, combine to create a worst-case-scenario. Sharpening makes noise more prominent, thus it is more difficult to remove. Sharpening should always be the last step in any photo development. You always want to create a noise-free base with which to sharpen on, otherwise you will be fighting against it all the way down the line. The proper order of general processing is:

1) Global and local exposure, contrast, and color adjustments (this alone can often mitigate noise)

2) Noise reduction (light)

3) Sharpen

4) Resize