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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Sensor issues?

Andreas Herzog

Andreas Herzog

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Hello.

I'm on a feature film starring Stellan Skarsgard with director Hans Petter Moland. This is as big as it gets here in Norway, and yes we shoot on RED:)

I'm the DIT and yesterday i saw some ugly lines running virtically down in the middle of the picture. It was very visible during dark scenes.
It is actually so bad that we need to reshoot the scene. I've now changed the body, and the lines are gone.

Is this a sensor issue?

I will send the camera for evaluation.

I've processed about 20TB of footage on this camera without this problem and I cant get my head around to understand what is causing this.

Anyone else had this problem?

I've reinstalled b17, black shaded, still there.
It is not a lens or filter issue! (same lens on new body and all is OK).

All the best!
-Andreas
DIT @ DFILM
 
Could be a sensor issue or something else. Can you post a frame that shows the problem? Anyway, best to contact RED...
 
Jeff is right, please contact us at www.red.com/support and include a screen shot in the support ticket request. It could be a number of things so we would need to dig a little deeper.

BC
 
OK.

Thanks for quick replies!

The "lines" are barly visible in a still frame, in motion you see them better.

This image has contast boosted to see it better in a still frame.

A010_C001_032782_00112.jpg
 
Andreas, I will forward this thread to tech support. Please, if you have not done so already, do file a support ticket on red.com.

Thanks, BC
 
Thank you kindly!

I will let the rental house do the paper work and sort out what to do.
I'm on set with new body, so its all fine for now. It was abit scary so I just wanted to know if anyone else have had this issue.

- I'll send you an email, Nate to discuss what to do with the scene with the lines.

-Andreas
 
David Mullen ASC said:
Looks like typical pattern noise from higher ASA ratings, i.e. underexposure. Most of it can be buried by crushing the blacks a little.
Click to expand...

I've had those lines. Its no doubt caused by under exposure, but I've asked for an explanation of the source of the lines several times from Red. I'd like to know if its predominantly a sensor characteristic, or redcode in origin.

I feel like the lines (the thickest ones) seem to occur in the same place in the image, which makes me think sensor, but it could just as well be redcode.

I'll probably run tests and see if I can determine anything statistically, perhaps create a correctio mask if possible.

I've found that adding noise to the image can help disguise the lines. Doing this, and/or blurring also, then blending back with the original frame, perhaps also with a mild grain etc helps. You must then use a good downsampler, or blur then downsample to create a usable 2k image.

There are times I would really like to use noise creatively, and dig deep into the darkness.. but then those lines stab me in the eyes
 
ronx said:
I've found that adding noise to the image can help disguise the lines. Doing this, and/or blurring also, then blending back with the original frame, perhaps also with a mild grain etc helps. You must then use a good downsampler, or blur then downsample to create a usable 2k image.
Click to expand...

Hey, you stole the technique I use in Photoshop to get rid of moire patterns in some scanned images.

Sometimes, if I can't get rid of the moire using a Median filter with a radius of 2 pixels, I will Add Noise to break up the moire pattern, then use the Median filter and downsample the image.
 
Curran Giddens said:
Hey, you stole the technique I use in Photoshop to get rid of moire patterns in some scanned images.

Sometimes, if I can't get rid of the moire using a Median filter with a radius of 2 pixels, I will Add Noise to break up the moire pattern, then use the Median filter and downsample the image.
Click to expand...

Thats because I'm tracking your every move with my keylogger :nerd:

I don't use a median filter though, thats not so good with these lines, something less adaptive, and more gaussian is better, and with a radius of about 5-7!
 
It was actually at 250 ISO.

Problem is that the lines goes trough the actorts face, so crushing the blacks wont solve it i think.
 
ronx said:
I've had those lines. Its no doubt caused by under exposure
Click to expand...

I'm not so sure. We did some tests with a new body, same lens, same lighting, same exposure. I could not see any lines at all in this test.
 
Andreas Herzog said:
I'm not so sure. We did some tests with a new body, same lens, same lighting, same exposure. I could not see any lines at all in this test.
Click to expand...

You may be right. My guess is you are, and that body swap test would seem to back it up, all things being equal.

I'm just passing on what Red told me. In my case the scenes were definately underexposed, but I don't like the lack of a technical explanation of the source of the lines.

If others can replicate these lines through underexposure, thats one thing. If not, I want a sensor that works because my personal uses for the R1 often don't involve lighting.

Well lit scenes aren't a problem, but I have seen (unless I'm imagining it), those lines in UK/Winter/overcast/daylight/noon using about a 1/96 shutter at 48 frames/per sec.

They're engrained in my brain.
 
Andreas Herzog said:
It was actually at 250 ISO.

Problem is that the lines goes trough the actorts face, so crushing the blacks wont solve it i think.
Click to expand...


What was your whitebalance, tungsten/daylight or did you make your own white balance?
By accident i made a wrong (not on a white board but shelf of al colored books) whitebalance and got al funny blue stipping grain.

Robert
 
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