Click here to go to the first RED TEAM post in this thread.   Thread: Bayer Pattern

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  1. #11  
    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.
    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?
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  2. #12  
    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.
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  3. #13  
    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.
    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...)
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  4. #14  
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    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.
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  5. #15  
    Senior Member Jeff Coatney's Avatar
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    Good luck, Xander.
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  6. #16  
    Quote Originally Posted by Xander Fischer View Post
    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...)
    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.
    Amateur Composer, actually well amateur everything.
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  7. #17  
    Quote Originally Posted by Xander Fischer View Post
    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...)
    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/ma...ial/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.
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  8.   Click here to go to the next RED TEAM post in this thread.
  #18  
    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
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  9. #19  
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    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.
    Maybe the video game is good.
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  10. #20  
    I think the original Lockheed prototype involved three 4K 8x10 sensors -- the camera was the size of a Volkswagon!
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