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Old March 30th, 2005, 07:57 AM   #16
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Jon - no aversion to sticking with your decisions, but if there are two ways of doing something with the same end quality and one allows options where the other does not, I'll take the options, every time (remember, we're talking about options in filtration and grading even if you do decide to stick with a B+W image in the end)...

As regards CCD's, yes - good point. I was assuming 3 CCD systems, however, in which the image must be combined into full colour before a desaturation can occur (otherwise the system is effectively applying a colour filtration to the image).

As regards the "more data head-room for desaturated images" argument, it's one I've seen and heard many times. On paper it's a *very* good point, however the DV codec is the DV codec, and is not optimised for monochrome performance and thus does not use this headroom in any way - you do not get lower compression with monochrome images. If the camera had a system to use a completely different codec in monochrome code, then yes, this would lead to higher quality final images - but it is not the case (at least not in any camera I have used).

Matthew: Doesn't sound stupid at all - if it works for you to shoot that way, then shoot that way!! Also, if you are definitely going to be shooting for B+W (as it sounds like you are), then you won't fall foul of any nasty suprises when you desaturate the image. You could, however, get the best of both worlds by shooting in colour but having your monitor set up with the colour turned right down to render a B+W image. A word of warning, though: DO NOT trust TV's as monitors for rendition of colour or for exposure - you'll get burnt. Look through the VF and judge it on that (and of course with zebras etc as normal, for exposure).

On a total point of pedantry, noir doesn't have to be black and white, of course!!! ;)
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Old March 30th, 2005, 09:37 AM   #17
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While I won't argue that you get lower compression by recording a B&W image, I will say that in my experience the type of color compression artifacts that arise from 4:1:1 sampling and the DV25 codec are eliminated when switching a capable camera into B&W mode. Such compression artifacts as blocky edges around reds and color "bleeding" are gone. Leaving you with what appears to be a much cleaner and clearer picture.

In my experience, in-camera B&W (for the above mentioned reasons), produces a better picture and thus is not the same quality as doing it in post.

I'll admit that I am likely coming from a different perspective than most others. But thought I'd share my opinion on the matter anyway.

Also, for what it's worth... I'm of the opinion that ANY CRT monitor professional or otherwise is far superior to ANY LCD viewfinder. Sure, a blatantly uncalibrated/overtuned consumer TV could do just as much harm as not using a monitor at all. But it's really not hard to set even a consumer TV to damn near the proper calibration. Regardless, always use those zebras.

I agree that noir doesn't have to be black and white. And for those on the fence about shooting color with options or if you don't have a camera that is capable of shooting in B&W, then any shifting of the color to a significantly lower saturation level is not a bad idea. By lowering the color saturation, you at least minimize the type of compression artifacts that befall 4:1:1 sampling and the DV25 codec. And you may even find that the lower color saturation did the trick for you without having to go all the way.

But I personally feel that shooting in B&W is a better way of working for me.
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Old March 30th, 2005, 10:18 AM   #18
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Fair play mate, of course you should do what your experience tells you to do...

I have to say that - whilst I know what you're saying re: CRT's - you need to be *bloody* careful, and the LCD/EVF should be your decision making tool, especially as regards exposure, imho. I was seriously burnt a couple of times on the first few digital shoots I lit because of overriding my decisions based on the output of an uncalibrated CRT monitor.

This is especially true under partially lit situations (such as night shoots, or - for that matter - noirish lighting).

By all means use a monitor, they are very handy - but to all people who are planning on using TV's just *please* be careful if it's not a calibrated, dedicated monitor. It's for your sake not mine!!!

BTW Jon, this advice is not aimed at you, but rather at those at the beginning of their DoP experience...

Oh, and interesting point about colour comp artifacts - not something I'd noticed, although the cameras I use are 4:2:0 or 4:2:2, which may lessen this effect (I'm no expert on this colour seperation business, and in fact wouldn't mind a decent tech run-down of the issue, if someone has the time...).

Cheers!
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Old March 30th, 2005, 11:03 AM   #19
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Yes, I've recently purchased a 14" Sony production monitor - my life has gotten much easier. One question, the monitor has handles so I'm thinking I could use it on location, provided there was a power source. I know this also probably seems stupid as in "of course you could", but is it bad for the monitor to be lugging it around? I haven't been able to find a case for it yet and thought maybe there was a reason.

Best,

Matt
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Old March 30th, 2005, 11:18 AM   #20
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http://www.justcases.com/monitorcases.html
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Old March 30th, 2005, 08:20 PM   #21
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I think one of the first projects I'm gonna do when I finally get my camera is make a black and white movie about Christmas. I sort of already know what I want to make it look like. I love the look of old-world Christmas.(especially in B&W) I'm gonna use forced-perspective effects using 30s and 40s style toy cars in front of my house to give that period look. Lots and Lots of music from that era. It'll be sort of my version of "It's a Wonderful Life" This will be so fun.
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Old April 1st, 2005, 01:41 PM   #22
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<<<-- Originally posted by Dominic Jones : As regards the "more data head-room for desaturated images" argument, it's one I've seen and heard many times. On paper it's a *very* good point, however the DV codec is the DV codec, and is not optimised for monochrome performance and thus does not use this headroom in any way - you do not get lower compression with monochrome images. If the camera had a system to use a completely different codec in monochrome code, then yes, this would lead to higher quality final images - but it is not the case (at least not in any camera I have used). -->>>

I'd have to respectfully disagree with this. For a monochrome image, the two chroma channels remain constant, and will compress using very little space. For low detail images, you wouldn't see much of a difference, and for very busy images, you'll still see compression artifacts, but for "ideal" images, you should achieve approximately 30% reduction in quantization artifacts.

Moreover, as Jon points out, the colour artifacts have a nasty habit of slipping through. If you just use a "Desaturate" filter, they'll be particularly prominent, because the image that you're left with is "lightness", not "luminance". Even if you correctly extract the luminance, if you're intending to use the colour information to modify the image, then you'll still inevitably see some of the colour artifacting.
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Old April 3rd, 2005, 12:01 PM   #23
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Sure, I understand what you're saying, but I was unaware (please correct me if I'm wrong) that the extra bandwidth was used to allow for better quality in the monochrome part of the image. There's no benefit to having an abundance of spare bandwidth, after all...

Jon's points re: colour artifacting are good, as I mentioned before, and not something I had considered - although, as you point out, they should not affect a properly desturated image and, although they may creep in again with the use of post filtering, at least the option is still available to you, if desired.

My position is, I think, unchanged - I'd rather shoot in colour and deal with the desat in post, and I think it's possible to get an image of equal quality through this method - but after all of the fantastic discussion here I will have to do some testing before I set out to shoot B+W footage!!

Thanks all!
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Old April 3rd, 2005, 09:47 PM   #24
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Yes, the "extra bandwidth" will be used, but it's not only that. The way that the signal is compressed uses adaptive quantization to "round off" the AC coefficients until the signal can be run-length encoded to 1/5 of the original size. Since the AC coefficients for the chroma channels in a monochrome image are always zero, they can be very efficiently compressed, meaning that the coefficients for the luminance channel don't need to be compressed as much to fit into the remaining space, but also that they (the chroma channels) can be compressed without error.

The colour artifacts can affect even a "correctly desaturated" image if your camera uses 0-255 (which most do) rather than 16-235 for luminance and 16-240 for chrominance, and the codec on your computer doesn't scale before converting to RGB. If the codec does scale, then you've introduced further quantization errors, and lost about 13% of your dynamic range. Moreover, as soon as you start using the colour information to adjust the luminance (which is the only reason that you'd want to retain the colour information) then the artifacts will appear.
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Old April 4th, 2005, 08:06 PM   #25
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Ah right, well then in that case I will humbly change my position! I was under the impression from previous debates that the compression was not adaptive - good info to know...

Thanks a lot!

:)
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