Bad pixels?

[jlaurili]

I have a couple question about bad pixels on the CMOS.

1) Is it likley that bad pixels will start to develop on the CMOS sensor over time?

2) Are the corrections for bad pixels on the CMOS, just the pixels that are discovered in the production process, or does it handle bad pixels that develop later (if they do happen).

 

[Christian Berg]

Very interesting. I don´t know but i think Red Cine should have a dead pixel repair function. Don´t know if that is done by auto or if it has to be set by the user. Just point out the pixel that is dead and Red Cine creates a mix of the surrounding pixels.

 

[Jarred Land]

Red will have dead pixel correction. Most cameras map dead pixels by checking the black calibration, shooting a black image and "looking" at what pixels are stuck on via a signal, then map those out.

 

[jlaurili]

I mention this, because many old CCD camcorders have bad pixels and the camera does not "fix" them. Then there is no choice but to do an expensive repair or live with it.

 

[jlaurili]

I understand that, but can the user do this for future bad pixels?

Red will have dead pixel correction. Most cameras map dead pixels by checking the black calibration, shooting a black image and "looking" at what pixels are stuck on via a signal, then map those out.

 

[ts1]

Dead pixel correction is easy to do in RAW and does not require your camera manufacturer's cooperation. That said, it would be nice if RED has this feature in its firmware.

 

[jlaurili]

Thats true, it can be fixed in post. And since a RED frame has so many pixels it would be easy to cover up without notice. It would be nice if REDCINE could do this, if it is not done in the camera itself. The camera could give the software the map it need to fix the pixels in processing.

Dead pixel correction is easy to do in RAW and does not require your camera manufacturer's cooperation. That said, it would be nice if RED has this feature in its firmware.

 

[Jannard]

We are beginning to implement dead pixel correction now... it seems like the least of our problems

Jim

 

[Jarred Land]

Dead pixel in software should be unnecessary if it is implemented in camera correctly.. but as mentioned it can always be done in post, its just less preferable.

 

[im.thatoneguy]

If RED fails at this task... and it would be a silly thing to do after all they've accomplished you can always do it manually.

I've corrected several digital cameras for friends by creating a shake script which will process all their files.

It's relatively simple: shoot a shot of the lens cap: Apply gain sufficient to make the overactive pixels white, and the proper pixels black. Invert and use as an alpha layer on an offset copy and Voila fast and dirty dead pixel correction. Best of all, once a camera is "tuned" you don't need to update the dead pixel map.

If you're really concerned about those .001% problematic pixels: you could use several layers and layer 4 copies at 25% for a linear blend from the bordering pixels.

Or if you were really amitious I bet you could even use the ColorMath node to do a bicubic interpolation.... point being. Don't worry about dead pixels, even if Red doesn't.

 

[Haakon]

If you're really concerned about those .001% problematic pixels: you could use several layers and layer 4 copies at 25% for a linear blend from the bordering pixels.

That's dandy for an image in Photoshop, but I don't want to have to be making four layers of my 4K project in post to have to deal with the issue. I'm with Jarred; I think a solution is best suited in-camera. That being said, I don't have any worries about RED dropping the ball in this area. They have their stuff together.

 

[Jim Arthurs]

One thing I've noticed over the years, is that the difference between dead pixel density at the exposure "sweet spot" and the density for long time exposures, which brings all marginal pixels to a head, so to speak. So any mapping in camera should be dynamic enough to handle these conditions if possible without a processing time period equal to the exposure.

Having said that, please, please, please allow us to actually shoot really long exposures, even if the sensor grid flairs up like a multicolored string of Christmas lights, and the damage can't be totally corrected in camera, because the value of such shots outweighs the trouble of processing them later in post.

 

[Lowkus]

Yeah, long exposures for photographic shots using the camera.