C200: Noise reduction uglyness

[J.Brown]

Okay, so been shooting and testing Canons latest C200 and I've found some issues when recording internally. I know that 35mb/s 4:2:0 is less than ideal and to use C-LOG is on the border to what's recommended but here it goes.

The image from the C200 with internal recording does not handle flat surfaces to well. There's a lot of compression artefacts and noise. But there are noise reduction that can be added to the internal recording and I figured this could improve things but it didn't. It actually made things worse without any real improvement.

Here's samples:

C-LOG 3 With NR turned off:

C-LOG 3 With NR set to 1:

C-LOG 1 With NR turned off:

C-LOG 1 With NR set to 1:


So what NR does on the C200 with 8-bit 4:2:0 LOG recording is just adding a bunch of serious banding. To me it looks like Canon has cut a few corners to short on the C200. First there are the compression artefacts and then they have implemented a useless NR.

Here are grabs using WideDR also:

WideDR NR turned off:

WideDR NR set to 1:

 

[Barry_Green]

I think you are conflating two things. The noise reduction might be working quite well; in fact, banding is the exact expected side effect of efficient noise reduction. I think you're probably blaming the NR for the banding, when in fact it is the low bandwidth compression that is causing the banding.

Watch the uncompressed live output, and you will likely be much happier with the NR performance.

That doesn't help with the onboard low-bandwidth recording though. The cleaner the signal, the more likely a highly-compressed image will develop banding in the gradients. The solution to banding has always been to add a little noise, actually, as the noise prevents the codec from making a blanket assumption that whole swaths of the image can all be compressed to the same shade.

If you try raw recording I would wager you would see more benefits to the NR.

When recording internally, you're apparently going to have to be aware of the limits of the compression, and watch for gradient banding. As you have already seen, you can minimize the banding by adding a little noise (but then, of course, the image is noisier...). The only real solution is to ditch the internal compression and go with raw or external high-bandwidth recording.

 

[J.Brown]

I think you are right. 8-bit and NR does not go well hand in hand.