OCT scanning for negatives

[Findlay]

I've just joined so please pardon if I have posted on the wrong forum. I was wondering if anyone has any idea whether the OCT scanning now routine for retinal inspection has ever been applied to film, in particular old negatives? Q

 

[MattKing]

For clarity - "OCT" is "Optical coherence tomography".
It is an interesting question.
I've mused before that lasers might have a role in a modernized approach to scanning, so the work with OCT equipment may be relevant to that.
Two problems I can forsee are the high cost of OCT machines, and the fact that, to the best of my knowledge, the technology isn't set up to deal with colour.

 

[Romanko]

I am not aware of any such applications. Tomographic capabilities could be useful in restoring old color negatives by obtaining the scans of individual color layers. I was considering using a transmitted light optical microscope but I no longer have access to one. It would be helpful if you could provide some background on why you are interested in it. Do you have an access to a OCT scanner? Are you working on a specific film digitizing project that requires an unusual approach to scanning? Or maybe you are just wondering if this could be done in principle.

 

[Findlay]

I am not aware of any such applications. Tomographic capabilities could be useful in restoring old color negatives by obtaining the scans of individual color layers. I was considering using a transmitted light optical microscope but I no longer have access to one. It would be helpful if you could provide some background on why you are interested in it. Do you have an access to a OCT scanner? Are you working on a specific film digitizing project that requires an unusual approach to scanning? Or maybe you are just wondering if this could be done in principle.

Thanks for the replies. I have an idea how to possibly extract colour encoding in old monochrome negatives by scanning layers. I only found out about OCT a few days back and think it might be worth an experiment. I haven't been able to get anyone interested. I had the idea about 20 years back but this might make it finally possible.

 

[koraks]

I have an idea how to possibly extract colour encoding in old monochrome negatives by scanning layers.

That would be magic. How would this work?

Welcome to Photrio!

 

[Findlay]

That would be magic. How would this work?

Welcome to Photrio!

Glad you think so! Please understand I have to be a little secretive about the process at the moment in case I can patent it.

 

[koraks]

Alright, I see. Well, good luck. I personally don't think there's a way that B&W materials preserve any color information the way e.g. Lippman plates do. I'd be interested to learn, some day once your patent has been filed, what the magic sauce is I'm missing out on currently!

 

[Findlay]

Alright, I see. Well, good luck. I personally don't think there's a way that B&W materials preserve any color information the way e.g. Lippman plates do. I'd be interested to learn, some day once your patent has been filed, what the magic sauce is I'm missing out on currently!

I'm in a bit of a dilemma because patents are expensive and difficult to apply internationally. I really need an entrepreneur to fund some experiments. I contacted Peter Jackson a few years back but was blocked by his PA. OCT might change the game but it is very difficult to get anyone interested

 

[Overrank]

I've just joined so please pardon if I have posted on the wrong forum. I was wondering if anyone has any idea whether the OCT scanning now routine for retinal inspection has ever been applied to film, in particular old negatives? Q

Not exactly what you want, but the following might be interesting - using X-ray tomography to scan a roll of movie film and extract the images ( without unwrapping, but instead cutting it into little cubes ) - https://www.bbc.co.uk/rd/blog/2017-12-morecambe-wise-video-film-archive-restoration

 

[Findlay]

Not exactly what you want, but the following might be interesting - using X-ray tomography to scan a roll of movie film and extract the images ( without unwrapping, but instead cutting it into little cubes ) - https://www.bbc.co.uk/rd/blog/2017-12-morecambe-wise-video-film-archive-restoration

Thanks for this, very interesting, I will have a good read. I think my process is a whole easier, shame I can't get anyone to have a go ...

 

[koraks]

I think my process is a whole easier, shame I can't get anyone to have a go ...

Draft up an NDA and see if you can get someone interested.

Peter Jackson - if you're talking about the director - that would be barking up the wrong tree. Try a small enterprise either in already involved OCT (e.g. an equipment maker) or a party involved in the technical part of photography or perhaps even the heritage sector.

PS: if you're thinking about 'decoding' colors by imaging different emulsion 'layers', you're in for a disappointment. I assume/hope you've got a different approach, otherwise it's dead in the water.

 

[Findlay]

Draft up an NDA and see if you can get someone interested.

Peter Jackson - if you're talking about the director - that would be barking up the wrong tree. Try a small enterprise either in already involved OCT (e.g. an equipment maker) or a party involved in the technical part of photography or perhaps even the heritage sector.

PS: if you're thinking about 'decoding' colors by imaging different emulsion 'layers', you're in for a disappointment. I assume/hope you've got a different approach, otherwise it's dead in the water.

I tried Peter because he colourised the WW1 film. I tried the British film museum/institute too. I think there is depth related colour information.

 

[koraks]

I think there is depth related colour information.

I see what you mean. I don't think so as the penetration depth within the visible part of the spectrum is unlikely to differentiate well enough, but see how far you can take it with an experimental route. Who knows!

 

[Findlay]

I see what you mean. I don't think so as the penetration depth within the visible part of the spectrum is unlikely to differentiate well enough, but see how far you can take it with an experimental route. Who knows!

It depends on the yellow filtration/absorption of the gelatin matrix

 

[koraks]

You'll have to look into that, but I'm not overly optimistic. Gelatin tends to be pretty transparent across the visible spectrum and even down into UV-A. It's one of the reasons it works so well with e.g. thick carbon transfer tissue, which is much thicker than any photographic film, but still transmits pretty much everything down to 365nm or so.

 

[Findlay]

You'll have to look into that, but I'm not overly optimistic. Gelatin tends to be pretty transparent across the visible spectrum and even down into UV-A. It's one of the reasons it works so well with e.g. thick carbon transfer tissue, which is much thicker than any photographic film, but still transmits pretty much everything down to 365nm or so.

It is pretty yellow when you look at it in the kettle ready to make the emulsion. Worth an experiment.......

 

[koraks]

It is pretty yellow when you look at it in the kettle ready to make the emulsion.

I don't think that's quite the same thing. But see if you can set up an experiment.

 

[Findlay]

I don't think that's quite the same thing. But see if you can set up an experiment.

Not sure when I will be able to but thanks for your interest!

 

[koraks]

Well, my interest is certainly piqued; please do keep us updated on your progress! The proposition itself is interesting, and despite my skepticism, I'd love to hear about what you find out when exploring this direction.

 

[MattKing]

What is perhaps even more interesting is whether any of the related technology and associated knowledge might be re-purposed for film scanning.

 

[Findlay]

What is perhaps even more interesting is whether any of the related technology and associated knowledge might be re-purposed for film scanning.

Might be a S/N boost as the Fourier transform allow for thousands of scans in a flash. Not sure about the resolution, currently 7 microns I think so fine for transparencies and old monochrome, maybe colour neg?

 

[Romanko]

I am also a bit skeptical of the method but please don't be discouraged by our comments. There is a research group in Zurich working on film restoration:

Results

Case Studies and Reports: Scanner Study Der Märchenwald (1919), a Tinted Silhouette Film Technicolor No. V: Switzerland Sportland (1952) Dufaycolor: Parures (1939) Strategy for the Restoration of t…

diastor.ch

There is also a conference that might be of interest to you:

Programme

Seventh International Conference Colour in Film, 2023 Colour and Underwater Film Dates: Monday, December 11 – Wednesday, December 13, 2023; pre-screening: Sunday evening, December 10, 2023 Ve…

colour-in-film.net

 

[Findlay]

Thanks for these. I am reasonably positive about the method. I published in the BJP about 20 years back about what I called the Single Colour Method, where a colour image could be obtained by shooting a normal image on monochrome stock and another image shot with a yellow filter. The process even worked using two unfiltered images shot on different makes of monochrome film, as a result of differences in spectral sensitivity.

 

[Romanko]

Thanks for these. I am reasonably positive about the method. I published in the BJP about 20 years back about what I called the Single Colour Method, where a colour image could be obtained by shooting a normal image on monochrome stock and another image shot with a yellow filter. The process even worked using two unfiltered images shot on different makes of monochrome film, as a result of differences in spectral sensitivity.

This is very interesting. Do you have a reference to the BJP paper?

 

[Findlay]

Single Colour Process, Stevens, A, Vol 149, No. 7389, 31. 7. 02