Noise reduction trials.
When I went for the m43 system from canon aps-c and full frame, a big point of worry was the noise profile and the ability to handle the noise. Being a smaller and older sensor, I was expecting it to have a poor noise profile. However, I am pleasantly surprised that it handles noise quite well and the raw files actually have enough data to allow a good amount of noise reduction with the latest programs. After much search on blogs, 2 programs were being recommended frequently. One was dxo photolabs prime, the other was topaz denoise. Of course there are traditional software like neat image and even nik define2
The first thing I tried was the topaz denoise which has been widely hailed as a revolutionary software. Indeed, the results iin some circumstances are exceptional. The target file I used was this image below, taken at ISO 6400
The red squares mark the areas I later compared for noise reduction. I have tried to include areas with shadows, details, color etc.
So first I loaded up the .orf file into topaz denoise. It was immediately clear that topaz was making a hash of the raw files (at least Olympus, canon raw seem to be ok). Topaz has 2 settings deNoise AI (slower but better), AllClear (faster but brutal). In Allclear there is remove noise: low, medium, high, and enhance sharpness: So in my notes when I say Allclear medium, high, it means settings are remove noise: medium and enhance sharpness: high
Most images below will be in a grid of 4 for comparison. Below the image, you will find the details. TL = top left, TR = top right, BL = bottom left, BR = bottom right
TL: denoise_ai_auto, TR: allclear_auto, BL: all clear: low, low, BR: allclear: medium low
Its clear that topaz denoise is making a mess of the color and also the noise reduction is too harsh.
Next I converted the raw file to tiff and ran it through topaz again. Below are the results.
TL: dxo prime, TR: tiff+allclear_auto, BL: unprocessed tiff, BR: tiff+denoise ai auto
TL: dxo prime, TR: tiff+allclear_auto, BL: unprocessed tiff, BR: tiff+denoise ai auto
Its clear from this that topaz is smoothening out the details and not doing a great job of noise reduction. DXO is doing a much better job of maintaining details.I think some sharpening has happened in above unprocessed tiff by mistake. It also has some weird artifacts in places.
The next thing I did was take this into dxo photolab. They have a very good noise reduction engine called prime. Unfortunately, its part of the photolab and you cant get it separately. Prime also has a few settings you can play around with.
TL: dxo_prime, TR: dxo_hq, BL: unprocessed, low, BR: raw+topaz allclear:medium, low
DXO also has 2 options: prime and hq. prime is better by far but only works on raw files.
On further research, I found out that many people are suggesting a 2 step process for high ISO noise reduction. So I check dxo+nik define2, dxo+neat image, dxo+topaz. Results as below
TL: dxo_prime, TR: dxo_prime+neatimage (auto), BL: unprocessed tiff, BR: dxo_prime+nik define2
TL: dxo_prime, TR: dxo_prime+neatimage (auto), BL: unprocessed tiff, BR: dxo_prime+nik define2
TL: dxo_prime, TR: dxo_prime+neatimage (auto), BL: unprocessed tiff, BR: dxo_prime+nik define2
TL: dxo_prime, TR: dxo_prime+neatimage (auto), BL: unprocessed tiff, BR: dxo_prime+nik define2
I feel that neat image is bluring the details too much. Nik define 2 is doing a better job of maintaining details.
Next I did dxo+topaz. Results as below
TL: dxo_prime, TR: dxo_prime+topaz allclear (auto), BL: unprocessed tiff, BR: dxo_prime+denoise ai
TL: dxo_prime, TR: dxo_prime+topaz allclear (auto), BL: unprocessed tiff, BR: dxo_prime+denoise ai
TL: dxo_prime, TR: dxo_prime+topaz allclear (auto), BL: unprocessed tiff, BR: dxo_prime+denoise ai
In conclusion
Topaz denoise is a great software and works in many cases. However it has a tendency to create weird artifacts and sometimes, it cant figure out whats noise and whats details so some detail can get lost. Topaz denoise also cannot handle .orf (Olympus raw) files very well. It really messes up the colors. It does a better job on tiffs. Overall, I think dxo photolabs prime did a really good job with high ISO. However, it falls short of total noise reduction and best results are obtained when combined with a second noise reduction software. For this, topaz denoise and nik define2 seem to be good. Neat image smoothened out the details too much for my liking. Its possible that this is because I used auto. Neat image has a huge amount of manual controls so its likely that netter results can be obtained.
Topaz denoise handles low noise files quite well, i would say upto around ISO 1600. But for anything over that, a 2 step process is definitely recommended.
Specific to Olympus I think the amount of details and information in the raw files is quite high. High ISO images in Olympus clean better than similar ISO images of aps-c sensor which I have tried i.e. canon 7d2. I think coupled with phenomenal image stabilisation, it’s a killer combination.
© Girish Vaze@2020