(just discussion) Scanning Film with an Monochrome Cam and Laser? - Page 1
Forum section: electronics / projects

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 14, 2025, 10:58:39 pm
content: HiI know I know there are that modern Camera with an Bayer Filter... I play around with mine "cheap" industrial Camera and I bought them to explore the world of Monochromatic Light. When I was in an east European City I come across multiple Sodium Vaper Street Lamps and though why not use Laser Light who have normally an very narrow Peak at there Wavelength and since I know what the Wavelength is everything Light wo shine truth the Film would mean it is Light and Black so by using Multiple Laser after each other I should later in post processing easy be able to stack the multiple Images together and get the best result? The Image must be in some kind of "RAW" Format to tweak each Wavelength separately. If it work I could not be the first one who think about that?!Thanks

author: Someone
author_rank: Super Contributor
timestamp: May 14, 2025, 11:06:04 pm
content: There are many commercial devices that already do this.

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 15, 2025, 09:28:48 am
content: I think so. I would like play around with my stuff. Is there some Images how the company do this?Maybe someone here work on, with such systems?Thanks

author: kmm
author_rank: Regular Contributor
timestamp: May 23, 2025, 09:41:10 pm
content: The principle is very similar to the OG three-color photography method, as proposed by Maxwell (of Maxwell's equations fame), just using different colored illumination rather than different colored filters. Totally will work, and as mentioned has been done commercially (at least in the past), although I suspect getting good results in terms of color balance and registration is where it becomes nontrivial in terms of optics and math.LEDs may be a better light source than a laser though. From the response plots of film I've seen the absorption peaks are fairly broad to begin with so a narrow band source isn't necessarily better than a broader one, and the coherency of the laser light is probably going to produce a lot of unwanted interference effects. You could scan with more colors than RGB(ish) too, although post processing this into a decent image may be difficult in the usual programs.The inverse is also used in sequential-color projectors, multiple colors of light sequentially fired at an image generation device that's synchronized and displaying the correct color channel, and then onto a screen and back to the viewer, where the image persistence and relatively slow response time of human eyes combine it into a color image. These are the sort of projector that looks a bit flickery and leaves a psychedelic afterimage when you scan your eyes across it quickly [not everyone may be able to see this effect though, very much dependent on your eyeballs].Not an expert in any of this, just enjoy playing with light from time to time.

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 25, 2025, 11:20:19 pm
content: Do you mean a DLP Projector?https://en.wikipedia.org/wiki/File:DLP_rainbow_effect.JPGI tough about a Laser because the give an very narrow Wavelengh. Maybe there are some affordable LEDs on the Market who have an narrow Frequency to but I found only some who are intend for Medical Imaging aka sstttt expensive.I think about befocus a Laser beam and bounce them into a "Diffusion Chamber" where the Light Rays could come out in a way that there are no hotspots.OMG I found an Article in German who is mental:https://www.edmundoptics.de/knowledge-center/application-notes/lasers/beam-expanders/

author: Siwastaja
author_rank: Super Contributor
timestamp: May 26, 2025, 05:42:10 pm
content: Why very narrow wavelength? Narrower improves color separation to certain extent - but I bet no one would see any difference between e.g. 1nm vs. 10 nm bandwidth; dyes in film originally are far from perfect anyway. You can easily get narrow wavelengths with filters - gelatin dye filters or dichroic, just with the expense of efficiency, but that does not matter much for applications like film scanning / copying / etc.So while narrow wavelength is an advantage of laser, it isn't unique to lasers.

author: helius
author_rank: Super Contributor
timestamp: May 26, 2025, 06:15:50 pm
content: Film scanning begins with the telecine, invented in the early days of CRT (electronic) television. A telecine is a film projector aimed at a vidicon tube and speed controlled to a multiple of the television frame rate. The telecine is limited to the resolution of the vidicon tube, which isn't very high.In the early 1960s, Ed Friedkin invented the flying-spot scanner, focusing a high-resolution CRT onto the film and detecting light transmission with a sensitive photomultiplier tube. By using a large enough CRT with a very small spot size, the resolution can be extremely high. By the 1970s, 4K x 2K resolution for 35mm movie film was achieved. Lasers were not used because the mirror galvanometer was not sufficiently precise or reliable. Improvements in galvo technology have enabled laser scanners, which became commercially available in the 1990s.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 26, 2025, 06:41:02 pm
content: Quote from: kmm on May 23, 2025, 09:41:10 pmThere was also a tablet with a (fast) monochrome LCD and RGB backlight that cycled through the colors quickly. The main reason they did that, however, was to have a monochrome mode similar to eink when the backlight is off.

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 26, 2025, 07:33:24 pm
content: Year Iwould likedo the same with an "Mobile" Setup.Well it is possible to use 3 Cams where the Calibrate with each other by shine the same Light source into each of the 3 Camera Modules so the all have the same Perception of Light and Dark.Sure I would not use the cheap and crappy Camera Module I use now to play around at Home.The major difference to the most system I saw who are scan the Image is I would need each Image in an "Image Format" rather an (Interlaced) Video. A good example is the Video I post above where the alignment is not perfect and image artefacts could be seen. That could be reduced when the Camera was mounted Stationary by "AI" Image Stacking.The first process should be to center an Image to an fixe known Point in the Image. Thankfully such "AI" thinks like Frame generation, Image extension when the Film was not perfectly center inside the Camera at recording Time.With all the fancy stuff who exist nower days it should be "easy" to recreate and get a usable Video out of some old Film.