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Post by Simon Broad on Mar 2, 2012 18:56:26 GMT
Could i ask: How do i get hold of a telerecording or a hd copy of dw or timeslip where i can see the chroma dots and use it on the Cr program propaly? ?
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Post by craigrothwell on Mar 2, 2012 19:11:37 GMT
Long time lurker here, but I've only de-lurked to ask Simon to please stop posting this Timeslip rubbish.
Simon, you clearly have no ability to grasp how this colour recovery works via this forum, stop spamming every thread with your questions about it.
If you are serious about doing it I suggest you read up on how the process works, what is required, and stop demanding everyone answer your absurd questions on this thread because you can't spend a few hours learning about colour recovery & how to use a graphical file converter.
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Post by rdenham on Mar 2, 2012 19:36:19 GMT
Could i ask: How do i get hold of a telerecording or a hd copy of dw or timeslip where i can see the chroma dots and use it on the Cr program propaly? ? Why? All of the black and white Pertwee Doctor Who episodes have been processed anyway And the high-def telerecordings are only available to people who are granted permission to use them, such as the Restoration Team, they won't hand them over to any Tom, Dick or Harry!
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Post by Simon Broad on Mar 2, 2012 21:23:42 GMT
I am being unfairly attacked again!! Plus you are going of topic
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Post by Rob Moss on Mar 2, 2012 21:26:51 GMT
Could i ask: How do i get hold of a telerecording or a hd copy of dw or timeslip where i can see the chroma dots and use it on the Cr program propaly? ? Why? All of the black and white Pertwee Doctor Who episodes have been processed anyway And the high-def telerecordings are only available to people who are granted permission to use them, such as the Restoration Team, they won't hand them over to any Tom, Dick or Harry! To be fair, there's more to life than Doctor Who episodes - there's loads of stuff which needs processing, but you're quite right, this is a tool for professional use, on high-resolution scans, which, quite rightly, are only available to people working in a professional capacity. It's not intended for people to take their black and white DVDs and try to make them into full colour.
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Post by Richard Bignell on Mar 2, 2012 21:36:16 GMT
I am being unfairly attacked again!! Plus you are going of topic You are not being "attacked", Simon. You're simply being told what you've been told many times before. This thread is proving useful for those who wish to seriously discuss the technique and mathematics behind the colour recovery process. Please don't derail it with your constant demands for source material.
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Post by Brad Phipps on Mar 2, 2012 21:45:57 GMT
HDCAM SR decks go for around ~120,000 pounds so start by getting one of those... then we'll discuss master tapes...
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Post by Richard Russell on Mar 2, 2012 22:36:39 GMT
What I'm not clear on, is what has been considered where the only surviving 525-line copy is sub-broadcast quality. That's what I was referring to in my previous reply. Because the luminance from the domestic off-air recording is of such a poor quality (even after RSC), switching between using that for the out-of-phase film inserts and the FR for the rest might be just as unsettling as using the FR for everything and putting up with double-imaged frames. Richard.
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Post by dennywilson on Mar 3, 2012 8:10:48 GMT
I have to confess that I find the whole process magical and mind-boggling, especially with the mathematics concerned, but it's brilliant that people are continually trying to find ways to make the process work better. I have to admit that I feel very much like Charlie Brown when talking to Lucy and Linus... ;D This Sunday strip was the basis for the pre-title scene for the first PEANUTS feature, "A Boy Named Charlie Brown". But I Digress....
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Post by Alex Weidmann on Mar 6, 2012 11:22:46 GMT
What I'm not clear on, is what has been considered where the only surviving 525-line copy is sub-broadcast quality. That's what I was referring to in my previous reply. Because the luminance from the domestic off-air recording is of such a poor quality (even after RSC), switching between using that for the out-of-phase film inserts and the FR for the rest might be just as unsettling as using the FR for everything and putting up with double-imaged frames. How about this idea: If the out-of-phase inserts can be corrected in the Betamax/Umatic recordings, then subtracting the corrected version from the uncorrected version will produce a mask for the double-imaging you want to remove. Assuming the Betamax/Umatic versions had been registered with the film recording, you could combine this mask with the FR in some fashion to remove the double-imaging (may just be a matter of pixel subtraction, possibly with a weighting factor). Can't test this myself as I don't have an RSC of the off-air recordings. However all the processing tools needed exist in AviSynth's MaskTools extension. Would be very simple to construct a processing script, and it should run close to 25fps.
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Post by Richard Russell on Mar 6, 2012 14:10:52 GMT
you could combine this mask with the FR in some fashion to remove the double-imaging (may just be a matter of pixel subtraction, possibly with a weighting factor). I don't understand what you're proposing here. If you try to remove the double-imaging with a 'mask' what you'll end up with is an area of black (or grey or something) where the 'unwanted' part of the image was. That would be far more visible and unacceptable than the double-imaging was in the first place! What you ideally want to do is to replace the double-imaging with what was in the original film frame, but a mask isn't going to allow you to do that. The very most you could do, as I see it, is in the situation when there's no 'global' motion (such as a pan or a zoom). Then you might be able to keep the non-moving (and therefore non-double-imaged) parts of the frame from the FR and replace the moving parts of the frame from the RSCed video. But, arguably, when there's no global motion the out-of-phase film isn't all that objectionable anyway. It's when there is global motion that ideally you'd like to be able to fix it, but then the only option is to replace the entire frame with the RSCed video. Richard.
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Post by Alex Weidmann on Mar 6, 2012 19:26:00 GMT
I don't understand what you're proposing here. The idea is that by subtracting the two Betamax versions you end up with a 2D scalar field of pixel-difference values across the frame. These values are integers: positive entries indicate that the unwanted double-image is increasing the brightness, and negative entries show that it is darkening the image. So by subtracting this scalar field from the film-recorded frame, you end up adjusting the pixel values by just the right amount to remove the double-image. In principal it ought to work on any kind of shot. I used a very similar idea to amplify my field separations, and it worked well for that purpose. Ofcourse it may well be that the loss in bandwidth when recording to Betamax, has permanently imprinted the double-imaging onto the footage, in which case my idea is useless.
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Post by Richard Russell on Mar 6, 2012 22:36:37 GMT
The idea is that by subtracting the two Betamax versions you end up with a 2D scalar field of pixel-difference values across the frame. These values are integers: positive entries indicate that the unwanted double-image is increasing the brightness, and negative entries show that it is darkening the image. So by subtracting this scalar field from the film-recorded frame, you end up adjusting the pixel values by just the right amount to remove the double-image. Sorry, it simply doesn't work. Using terms like '2D scalar field of pixel difference values' instead of 'difference picture' doesn't affect the fundamentals. Let's suspend disbelief for a moment and imagine that you could scale and warp the FR image so that it lines up perfectly with the off-air video image. Suppose further that you could adjust the luminance transfer function (e.g. gamma) so the two images match exactly in level. Now if you perform the subtraction operations you describe what you end up with is a picture that (in the region of the double-imaging) is no better in quality than the off-air image! So you might as well do what I suggested: replace the region of the frame in which the double-imaging occurs with the off-air video. It's much simpler, doesn't require precise alignment, doesn't require precise matching of gamma, and gives results that are just as good (quite possibly better, because the noise originates only from the off-air image, not from both as it would using your technique). Richard.
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Post by Alex Weidmann on Mar 7, 2012 12:50:34 GMT
Think I'm out of ideas then I'm afraid. The only other one I had is deconvolution, with the spot-wobble as the convolution function. I don't have any expertise in that area, but am very doubtful it could work. There's some free software called MeeSoft Image Analyzer that allows you to experiment with deconvolution (under the filters drop-down). The idea would be to create a Reverse Spot Wobble process to recover the line-structure.
Re: the 405-line era of "Dr, Who", I can't see any obvious remnant of the original line-structure on the Hartnell DVDs. The only obvious frequency signature is produced by the VidFire process. However I think if there had been any signal at the original line-frequency (or half the line-frequency), it would've been carefully filtered out to avoid beat-products forming with the 576i line-structure produced by VidFire. So the DVDs don't really tell me anything about what may be preserved on the film.
Some of the Telesnaps from the 1960s do appear to retain obvious line-structure (e.g. "Evil Of The Daleks"); though the frequency spectrum is completely obscured by JPEG compression artefacts. Would be quite interesting to see the 2D FFT of an uncompressed Telesnap image. The type of CRT seems quite different from that used by film recorders: I suspect it had less spot-wobble and less distortion. May well have been a larger screen. It might be possible to do field-separations on some Telesnaps; though I can't see it would serve any useful purpose.
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Post by Alex Weidmann on Mar 7, 2012 14:52:33 GMT
So you might as well do what I suggested: replace the region of the frame in which the double-imaging occurs with the off-air video. Just one last thought occurs to me on this. If the background is static, you could use a neighbouring frame from the film recording to replace the double-imaged area. That way you avoid degrading the picture quality. As far as I know SVS already do this for some of the double-imaging, probably with the same software they use for painting out dropout, where they "paint through" to a neighbouring frame. I think it's all done manually at the moment though; whereas a mask may just allow a more automated process. Let's suspend disbelief for a moment and imagine that you could scale and warp the FR image so that it lines up perfectly with the off-air video image. N.B. I actually had in mind the opposite: warping the off-air VT to the film. Near-perfect alignment can actually be achieved either way round using my ImageJ macro. This is an experiment I did 2 years ago. But the process is painfully slow, and I agree it would be better to do an approximate alignment.
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