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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 :)

85 filter?

Damn good to know the answer to this. Yeah, blue filtation sucks light up like a big dog. My entire thinking path on this thread was with the much weaker 85 series going the other direction.

I love being wrong when what I'm wrong about benefits me. :)
 
Jannard said:
We think you will NOT want to add filters when you shoot the RED ONE in tungsten. 1st off, if you did add a filter, it should be an 80B (or thereabouts)... not an 85. But the light loss is worse than the correction. We are going to do complete testing on this in the next few weeks.
Click to expand...

Maybe I missed something Jim, but how are we going to see the "correct image" on a set? Am I correct that we are going to be able to "white balance" and that setting will color correct to the monitor and also put the number in the meta data for later CC?

Matthew
 
macville said:
Maybe I missed something Jim, but how are we going to see the "correct image" on a set? Am I correct that we are going to be able to "white balance" and that setting will color correct to the monitor and also put the number in the meta data for later CC?

Matthew
Click to expand...

"The one operational clarification I'd offer to this is that the images through the viewfinder and monitor ports can look off color if you don't set white balance or hit the Auto White Balance from time to time. Again this does NOT affect the RAW data, and WB information IS stored with the RAW data as metadata, but adjusting (or having the camera recalculate) white balance as you shift between different color temperature lighting conditions - such as indoor to outdoor - is the only way to prevent a color cast in your viewfinder and on your on set monitors."

Stuart English
5/3/07
RED User
http://www.reduser.net/forum/showthread.php?t=2196&page=3
 
Yes, through the RGB pathway, monitoring appears correct (and if I do say so myself) and rather pretty.

Graeme
 
Here is my understanding about color images and RAW Bayer Pattern, which comes not from RED but from my DSLR.

It's all about the green channel. The ideal RAW Image has the most information or the best histogram on the green channel. Why? It's really about demosaicing.

It starts like this: Most images found in nature have more variance in luminance than in hue. Hue is determined by the ratio of color values at a given pixel value. Using the bayer filter we do not know for example the specific Blue value on a pixel that is filtered Green but we have a very good guess of that value because we know that the ratio of Blue/Green values between two neighboring pixels is going to be very similar. So the Green value will help us guess the blue value. A 4K Bayer Pattern chip camera is better than a 1.5K 3 Chip camera (without pixel shifting) because the overall luminance values across the image can be reconstructed with decent accuracy.

There are many different approaches to demosaicing a Bayer pattern image. We use complicated algorithms to try and fill in the blanks. But because there are twice as many green pixels in a checkerboard pattern most algorithms start by interpolating the green channel and then use it as a guide for the red and blue channels.

The practical upshot of this is that heavy color filtration that effects the green channel will effect the demosaicing process, thus effecting the percieved detail quality of the final image. An image that is lacking variance (a full range of exposure values in the green channel) might suffer from issues that have little to do with color. A constricted or noisy green channel might interpolate the entire image poorly.

So this is really going to take some testing to know this for sure but my intuition is that in a situation where the RGB Parade shows green is strongly shifted in one or another direction it makes sense to correct color in front of the lense. Even if you will shift it back in post it may be better to do this work after interpolation.

That's my feeling. I'd love to see Gibby's team do some tests that address this specific issue.

IBloom
 
Yes, green is important, but algorithms can be made so as to be very tolerant of the image data and do a good job pretty much no matter what.

Graeme
 
Hopefully this quesrtion/suggestion is not taking this thread off topic, but with RAW colour correction is there some function in RedCine to take an image of a GretagMacbeth ColorChecker chart and quickly balance the image to it? I've seen an addon to Photoshop that does this but it costs money and you'd think Photoshop would have this built in:

http://www.pictocolor.com/incamera.htm

This would be a great addition to RedCine if it could be implemented!

Cheers Red Team!

Paul
 
The colours are defined to the camera already. All you have to do is pick a white point.

Algorithms - I've written about 20 so far. We're using "nice" as our goal - overall image, rather than going for extreme sharpness. If you aim for extreme sharpness you get "bitty" results that just don't look good under motion. If you liked what you saw at IBC on the big screen, you'll like what we're doing.

Graeme
 
Graeme Nattress said:
The colours are defined to the camera already. All you have to do is pick a white point.

Algorithms - I've written about 20 so far. We're using "nice" as our goal - overall image, rather than going for extreme sharpness. If you aim for extreme sharpness you get "bitty" results that just don't look good under motion. If you liked what you saw at IBC on the big screen, you'll like what we're doing.

Graeme
Click to expand...


Graeme is it feasible and desirable to have the algorithims user defined (or custom made at the factory) for specific shooting environments where the camera isn't doing double duty.

ie
Bluescreen
Underwater
Aerial

For aerials for instance we would be interested (most of the time) at maximising resolution of fine detail (often foliage) and not so interested in sensitivity

Perhaps Underwater we would wish for sucking in as much red/yellow as possible.

For Bluescreen perhaps greater tonality of blue (if you get my drift) to allow easier removal of spill.


Does tweaking algorithums do much to the above list?



Mike Brennan
 
I don't think demosaic effects much of the above, other than resolution for your landscape. Problem there is put too much detail in, you might get buzzing or artifacts as the detail moves, which is not to bad for a DSLR still where you can go in and hand tweak, but that's not suitable for movies - we've got to look at the time dimension too.

Graeme
 
Mickjoebill said:
Graeme is it feasible and desirable to have the algorithims user defined (or custom made at the factory) for specific shooting environments where the camera isn't doing double duty.
Click to expand...

I think all Debayering algorithms are implemented in post, via REDCine. So you'll have your choice and don't need to worry while you're shooting. As far as I can tell the camera itself only downscales images from the bayer pattern, a much more straightforward task. NOT debayering in camera, while still compressing, is part of what makes RED's pipeline so special.

IBloom
 
We do full debayer and downscale in camera for the RGB recording pathway for best quality. For RAW recording, it's done in post.

Graeme
 
In camera, yes.

Graeme
 
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