Absolutely - and first to be clear, I am talking about opening up DeNoise AI independently (so not calling it as a plug in), and opening a NEF file in it.
What I see is far more destruction of details and depending on the file, some color shift. But detail destruction is my biggest issue and because you can't save as a raw file again, that destruction is permanent - so in effect you create a TIFF without the benefit of a far more advanced RAW conversion engine upfront (Adobe or C1 or Nikon) and detail retrieval gets hurt in the process.
You don't have that issue if you convert from RAW to TIFF first (in any superior converter) and then remove noise with Denoise AI - I have no idea why that is.
Just as an illustration I ran a very quick test ( had not used DeNoise AI on a raw file in weeks so I wanted to see if the more recent updates had improved things).
So here is a 1:1 crop of a NEF file properly exposed at Iso 2000. This just has a camera neutral profile applied, no noise reduction, no sharpening. It is exported as a jpg without resizing with sharpening for screen "normal" intensity. So it is about as minimally processed as possible in LR. Remember, this is a 1 to 1 pixel crop - so you don't benefit from any downsizing smoothing you'd normally get when creating a file to share on screen, but that's the best way to show the differences (ie I would never do it this way to print or post).
View attachment 23112
Here is the same file, exported as a TIFF first then processed in Topaz Denoise PlugIn inside LR, with the automatic settings. It is then exported as a jpg, no resizing, sharpening for screen, Normal intensity. So it's really the same file as above but cleaned first with Topaz. Keep in mind, this is about as worse case scenario for Topaz as possible. You'd normally Denoise a much larger crop first and then crop more tightly after noise removal to give the AI more data to work with.
The file cleaned up very nicely and although there is a slight loss of sharpness it would be quite easy to recover.
View attachment 23113
And finally, I opened the same NEF directly into Denoise AI and let the software pick the best settings. I exported as a TIFF 16bit from DeNoise and imported that file into LR then cropped it to the same 1:1 view as the previous 2. In theory, that method has the advantage of having the Topaz AI work with the full file and cropping happening only after noise reduction. I exported it then from LR as a JPG with th exact same settings as the previous 2.
First you'll obviously notice the very different exposure balance and actually, if you go to the exported TIFF you'll notice that some of the feathers on the throat are very close to clipped when the first 2 files really show you that they are not even close to clipped. There is no way to avoid that, Topaz picked the exposure and because it can only export a denoised file as a TIFF, the damage done is not recoverable.
Now the background is much cleaner but the loss of detail on the head and belly feathers is what bothers me more - in this file the damage is not too severe but go to an ISO 4000 file and it is massively destructive.
View attachment 23114
I hope that helps illustrating what I mean - Denoise AI is not a state of the art RAW converter but it is close to state of the art for noise reduction. So I use it at its best and leave out the rest.
