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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 :)

Bayer Pattern

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Xander Fischer

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I'm doing a research project on Film vs. Digital Cinema, and it's been a really good excuse to delve into very in-depth research. As with many people, I have always favored film, but the digital revolution has got me questioning my loyalty...

Anyway, since film can be scanned at true 4k uncompressed RGB (4k red, 4k green, 4k blue, no bayer pattern cop-out) I was wondering if there are ANY digital cinema cameras that do not use the Bayer sampling technique? In other words, are there any digital cinema camera that is able to exactly emulate the bit-depth, color space, and true 4k+ resolution available with 35mm?

Any help, or research/reference suggestions would be great (especially to any credible books, or scholarly articles, considering that this is a college research paper).

THANKS!
 
You can scan VHS at 4k RGB uncompressed if you want, but it's still VHS.... If you think 35mm film has 4k+ resolution, then come back with some images, because when measured, it does not. Perhaps you should start with my posts here on why a Bayer pattern makes the most sense by efficiently using the available photosites in the most perceptually relevant way.

Graeme
 
Xander Fischer said:
I'm doing a research project on Film vs. Digital Cinema, and it's been a really good excuse to delve into very in-depth research. As with many people, I have always favored film, but the digital revolution has got me questioning my loyalty...

Anyway, since film can be scanned at true 4k uncompressed RGB (4k red, 4k green, 4k blue, no bayer pattern cop-out) I was wondering if there are ANY digital cinema cameras that do not use the Bayer sampling technique? In other words, are there any digital cinema camera that is able to exactly emulate the bit-depth, color space, and true 4k+ resolution available with 35mm?

Any help, or research/reference suggestions would be great (especially to any credible books, or scholarly articles, considering that this is a college research paper).

THANKS!
Click to expand...

There is a lot of info on this site about this... starting with the fact that a 4K scan of film does not yield a measured 4K resolution. Slow film (ASA/ISO 100) is about 3.2K... same as 4K bayer from a RED ONE. Fast film (ASA/ISO 500) measures about 2.8K resolution. Also note that 1080P cameras do not measure a full 1.9K resolution. The best we have found is the Sony F35 which measures 1.7K... or roughly 1/4 of the best 4K film scan or RED ONE. EPIC's 5K measures 4K.

There are a lot of other factors that should be considered besides resolution. Like color (shooting RAW vs. a codec), dynamic range, grain, feel, etc.

Jim
 
Graeme Nattress said:
You can scan VHS at 4k RGB uncompressed if you want, but it's still VHS....
Click to expand...

Lol, I freakin love that quote.

Pixel peeping is useful if it imparts greater understanding of how to use a tool, but I'm getting to the point where I just want to know if it looks good and feels good, and Red slam dunks that. Now I find myself wanting to put all sorts of glass filters on the front, which I'm sure is nose-diving my "measured resolution" but ends up making very nice imagery.
 
RED One M, verses M-X methinks.

Graeme
 
Shawn Nelson said:
Wait, wasnt Red @ 4.5k actually measured at 4k per Jim's 'myth debunked'? Or was there a glitch in the test that put it back at 3.7k? Doesnt matter either way to me except to be correct when repeating numbers.
Click to expand...

That was the original post... we squeezed more out of the M-X sensor but I thought I would leave the conservative number.

Jim
 
To answer the original question, there is no three-sensor digital camera that captures RGB separately at 4K per color. All cameras with sensors larger than 2/3" have opted for a color filter array (CFA) over a single sensor, whether Bayer or the RGB striped pattern used by the Genesis / F35 sensor. It's just not feasible to have three separate 35mm sensors in one camera. Not to mention 3-sensor cameras require a prism block, which introduces other problems & limitations.

It's a bit academic though... just because 35mm should be scanned at 4K per color... it doesn't necessarily mean it resolves 4K per color. For one thing, you generally want to scan at a higher resolution that what the original contains, and secondly, the individual color layers of film stock aren't equally sharp, as anyone who has shot a scene in red lighting can tell you.

It's the problem of confusing scanning resolution with measurable resolution, and describing film resolution in terms of pixels.

I also think that some people are using resolution measurements of 35mm still photography (36mm wide negative) to describe 35mm cine photography (24mm wide negative.) That and confusing optimal scanning resolution with measurable resolution.
 
Wow... Well, thanks for the instintanious replies. I dunno, I was finlly pretty much sold on RED with the whole mx sensor release and the looming presence of Epic, but I just don't know anymore.

I've been looking around on Kodak's website a lot, and here's where my original inquiry in this post stemmed from:

In very simple terms the Bayer Sensor, which is often at the center of the 4K digital capture claims, does not capture 4K images. It outputs 4K pixels, but these are shared between red, green, and blue. A frame of 35 mm film, when scanned at 4K resolution, outputs 4K of red, 4K of green, and 4K of blue, all uncompressed. Even more information can be extracted when scanned at 6K.
Click to expand...

I'm not a total idiot. I know that resolution is certainly not the only thing to consider when assessing the "supremacy" of an image format, but being able to extract the kind of 'raw' data that you can from film is going to subsequently effect bit-depth, color space, and the resilience of the footage as far as post-processing/vis effects are concerned, yes? Considering that no digital cinema camera can preserve the same kind of information that celluloid can, this gives it a quantifiable advantage over d-cinema... or at least a uniqueness to it (regardless of whether or not it's perceptible to the human eye).

Graeme, I'm not doubting your credibility, because you obviously know a lot more about this than I do, but your VHS analogy seems a little irrelevant, considering that film has exponentially greater potential for preserved data when it's digitized. I also read on Kodak's website that certain stocks can be scanned at up to 200 lines per mm (under prefect conditions, namely lighting, as David was saying) which would definitely give you 4k+... as for images, I'll get back to you... Who knows, I'm probably wrong.

Also, David, is that what a digital cinema camera would need in order to feasibly process color in the same way a scanned 35mm neg can? Would there need to be 3 separate, 35mm sized sensors? considering it could be done (and ignoring the limitations of prism technology) would this provide any significant advantage over a single sensor with CFA?
 
See: http://reduser.net/forum/showpost.ph...2&postcount=24

Graeme
Click to expand...

Thanks, I'll check this out. Sorry for my hasty questioning- I usually browse the forums extensively before asking a question like this, because I never doubted it had already been discussed, but it's just that I'm running out of time before the due date.

So thank you for humoring my "easy way out" approach.
 
I also think that some people are using resolution measurements of 35mm still photography (36mm wide negative) to describe 35mm cine photography (24mm wide negative.) That and confusing optimal scanning resolution with measurable resolution.
Click to expand...

I think that's probably true...

Why the hell do they call it 35mm motion picture film if the negative is 24mm??? (I've only worked with 16mm due to budgetary concerns, so please excuse my ignorance...)
 
Hey Xander, good luck with the research. This topic has so many moving parts that it is hard to even get ones head around the topic. Between capture, editing, finishing, and distribution it seems really tough to contemplate. Almost every "film" turns into bits at some point and as time. Whether it gets distributed as a TV broadcast, Blue Ray, or projected as Film or from a file all makes a difference. I do think that at this point in time things are in a great deal of flux, but currently digital is not lacking in the comparison.

As for the resolution thing really try to examine some of the arguments that are made. There is a great deal of slight of hand going on when people discuss it. I remember watching the Panavision lectures where the scientist did exactly what you did suggesting that every pixel value (for lack of a better word) should be counted as unit of resolution. If you just think about it logically you would easily conclude that even if there was a perfect lens and display technology you couldn't actually fit 3 pixels where one goes. I mean assuming you have a 1920x1080 (2,073,600) screen receiving an image from a 1920x1080 3 chip camera, it's not going to turn into a 6,220,800 pixel image. There is no more than there is. What has been shown over and over and over again is that the images from the current RED cameras resolve better than film. What is also happening is that films advantages are being eroded in other areas as well.

With regards to Bayer patterns and sensor striping, its a little bit of magic.

What I think most people can agree on is that digital is quickly advancing in image capture.

Lastly it's all a matter of taste. Philosophically I like the most resolution, least noise, least grain, squeaky clean image that can be had. I'll go to post to give it the "film" look if I need it.
 
Xander Fischer said:
I think that's probably true...

Why the hell do they call it 35mm motion picture film if the negative is 24mm??? (I've only worked with 16mm due to budgetary concerns, so please excuse my ignorance...)
Click to expand...

Because the distance between the perforations is 24mm. The film's width is 35mm. The difference is caused by the difference in orientation between cinema and stills. In cinema the film is oriented vertically, giving a 24mm width, while in stills it's oriented horizontally, giving a 24mm height, and allowing for a 36mm width. Height for cinema depends on whether you're shooting 2, 3, or 4 perf.
 
Xander Fischer said:
I think that's probably true...

Why the hell do they call it 35mm motion picture film if the negative is 24mm??? (I've only worked with 16mm due to budgetary concerns, so please excuse my ignorance...)
Click to expand...

Well, 16mm only has an image that is 11mm wide or so -- "35mm" and "16mm" refer to the outer dimensions, the width of the strip of film, including the perfs, not the inner area used for the actual image.

35mm still film runs sideways, like VistaVision, and is 36mm x 24mm, 8-perf long, whereas movie film runs vertically and the image is 24mm wide, how tall depends on whether it is 4-perf or 3-perf, etc.

You are never going to get a straight answer regarding the measurable resolution of film, you can try shooting your own tests I suppose. "4K" is a loose figure is all I can say, more of an ideal in terms of film. Certainly film should be scanned at 4K, some even say 6K, but it often measures somewhere below 4K in terms of detail -- but more than 2K, which is why it shouldn't be scanned at 2K.

This article demonstrates why 2K is insufficient for scanning 35mm:
http://digitalcontentproducer.com/mag/video_digital_cinemas_special/index.html

Cramming three 35mm 4K sensors & a prism block into a digital cine camera just isn't going to happen, though it is theoretically possible. Not to mention that's 3X the data to record compared to a Bayer-filtered single 4K sensor. CFA's are here to stay.

It's always a bit misleading to describe film on digital terms, with words like "color space", "bit depth", "pixel resolution", etc.
 
With film, you can scan as high as a rez as you want, but before long you're just getting better definition on the grain, and that's not picture information. For Kodak to say what they say is exactly my argument about VHS - just because the scan is 6k doesn't mean there's 6k of information in there. Only way to know is go and measure it. Take a look at some film scans and see what the grain looks like and what the detail looks like.

As David (listen to David - he's a moderator here for a reason - knowledgable and respected) says, a 3 chip approach breaks down as you go to larger sensor sizes and prisms are not without their own set of compromises. Similarly, the RGB stripe approach from Sony / Panavision has noticeably rez than the RED One 4k, and the RED shows a much better MTF at 2K too. Not only that, but the stripe approach leads to mis-aligned RGB channels which somewhat negates the claim that it's true RGB.

The subject of resolution and detail and human perception could take a whole book. There is no one correct technology. Film has grain and the colours all focus at different levels. 3 chip doesn't scale large. RGB stripe has the offset issue and more aliasing. Bayer is complex (for me to decode, not for you - you just use it) and people are biassed against it, but it works, works well, and is an efficient use of photosites to provide to the viewer the most perceptually relevant detail.

So - what do you do - you test and measure. In the end, that's all you can do too.

Graeme
 
Slightly O/T, but wasn't the Lockheed Martin '4k' Camera prototype (I think it had blue in it) a three chip solution? I'm convinced someone (actually, was it NHK or Dalsa) tried putting three s35 sensors behind a prism.

This is me in camera geek/odd design geek mode.
 
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