HDRx Noise/Artifacts

[Michael Millichamp]

So, I was shooting with an Epic this weekend, and had a shot of a tree I really wanted to get. Problem was, the sun was hitting the background pretty harsh. Never having done HDRx, I tried it out, and maybe it's my lack of knowledge of it, but I have found a good amount of noise on the tree I was shooting and degrading of the image. The background is fine, but the tree is noisy and jittery when I play back the footage.

Am I doing anything wrong? Maybe the blend is messed up. Im not quite sure, but I need the shot, and would rather not go back and reshoot it.

Thanks guys.

[Nils Ruinet]

What compression were you shooting in ? Sometimes for shots with loads of detail it helps lowering the compression. Also, how does the footage look if you look at the 2 HDR streams separately ? Did you view it in full debayer quality ?

[Michael Millichamp]

I shot it at 10:1, and im looking at it in a full debayer quality.

The two streams separate, look equality noisy.

[Teague Kennedy]

May be the same issue as was stated in thread "Crazy Epic Artifacting." Since you were backlit and shooting 10:1 the issue would be compounded. Red is looking at this well known issue.

[Michael Millichamp]

Teague, that is exactly what im experiencing!

A frame grab is fine, but in motion, it's pretty noticeably bad.

Hopefully there is a fix for it.

[Mark Andersen]

I have scene random noise pop up in strange places, like tree trunks, which is where I actually had noise issues myself. Its kind of mysterious, certain colors and tones and textures etc. just seems to get weird. The one constant is that it always seems to happen in 3/4 tones, the dark but not black areas of the frame. Using minimal compression and over exposing and then pulling back down in post seems to help.

Edit: I've seen two kinds of noise, typical tiny grain like noise, which i dont mind, and the strange crawling texture noise (for lack of a better description) I assume you are talking about the latter. It's my belief that this weird crawling texture we sometimes see is not simply digital gain or noise but something related to the debayering process and the sensor getting confused with the "pixel picking". It seems to be the result of inconsistency from frame to frame in certain tone and texture combinations which create a strange noisy crawling texture. Maybe I'm nuts, someone chime in here, I'd like to here what others have to say.

[Michael Millichamp]

Here are some examples.

In the stills it's not too bad, but once you get going in motion, it's incredibly noticeable.


A005_C035_0317OD by MichaelMillichamp, on Flickr



A005_C035_0317OD by MichaelMillichamp, on Flickr

Any more information on this?

[paulherrin]

send me the shot, michael - i'd like to see what's going on. i haven't even tried/needed to shoot hdrx on my camera yet, but i guess i could test it. you obviously have a LOT of juicy and various levels of detail/contrast in the shot, which is extremely taxing on the compression. give me that thing and we'll see if it can be salvaged. :)

[Mark Andersen]

Yup, I'm sure you are getting the weird crawling noise that I have seen too.

Edit: This is the one area where film behaves a bit better. I'm sure these issues will improve in time.

[Les Dittert]

The bottom image, of the tree trunk, looks like the compression went a bit wonky on it. That is not noise at all. It's a sign of over compression ( too lossy ). The soft blotches are the things I am talking about.
Perhaps the compression was 'overwhelmed' by all the detail, and something had to give.
Can you post an r3d still image ?