Experiments with RGB-colored screens... a la Dufaycolor & Autochrome

[Photo Engineer]

Well, since C/M/Y can effectively produce all colors through any subtractive system and since R/G/B can effectively produce all colors through any additive system, then a set of filters and dyes (or phosphors) that match, are not too narrow or too broad and which do not have a lot of unwanted absorptions would be suitable. I know that this is vague, but each combination is unique and must be judged by itself. I often combined dyes in films or papers and then made pictures and had them judged.

Since each person has slightly different proportions of the color sensors in their eyes, each person sees things just a tad differently. So, judging is important. After a while you get a feel for what might be right and what might be wrong. This is not an exact science!

Sorry, but that is the best I can do. After the fact, you can often prove the reason behind a choice better than you can before the choice!

PE

 

[Ray Rogers]

I just mean to say that we have 3 rods in our eyes, one for red, green and blue, so why shouldn't 3 narrowband segments be able to reproduce all colors?

Again, I have been slowly typing stuff you guys have already touched upon.
Sorry

Well that was one of my points all along...
we can experience color in the absence of light...

but ordinarily there is a clear stimulus...
and ordinarily we are not asked to see color based on the stimulation produced by
3 single wavelengths no matter how many of those 3 are availaible.

We usually see by being stimulated by a multitude of different wavelengths,
even though they might all be of the same group, color or hue.

There are processes that might make color vision difficult under some circumstances... for example fatigue. that is one reason why we shift our gaze... even by very tiny amounts...

I don't know.
I suspect someone somewhere has tried to run these experiments (colored vision with only 3 wavelengths vs narrowly-mixed wavelengths), I just don't know where.

This all relates to processed material anyway.

From light source to vision there can be quite a lot of layers and transistions and I thought it worthwhile to give it a few minutes thought.

For anyone who cares, the conclusion I came to was perhaps a series of tricolor filters that all had the same filter factor would not be the ideal for me afterall.

(Of course, it really depends on the total overall system.)

Ray

 

[Ray Rogers]

James Clerk Maxwell... and no I don't have any specific reading material, other than the Bolas book (which by the way I will PM those page numbers shortly). But he was a big researcher in color sensation and of course demonstrated his "full"-color tartan.
---
PE, perhaps you could clarify the meaning of coherent light; I think I've misunderstood its meaning.

Ah Bolas, I see. Ok.

As for coherency,
I wonder if experiencing the concept as applied to sound would help?

Somehow I envision it as something akin to, or an extension of the concept of polarization....
or a marching army

Humm, is there such a thing as "polarized" sound? :confused:

 

[Photo Engineer]

Ray;

You cannot experience color in the absence of light. Sorry.

PE

 

[Ray Rogers]

Actually, you can.

 

[Ray Rogers]

(Your statement can only be correct if you qualify it! )

There are several methods COLOR can be seen in the total absence of light.
A knock to the head.
Pressure on the eye ball
Dreams
Hallucination (schizophrenia, DTs (?), sensory deprivation etc.)
Direct stimulation of the brain by a neurosurgon (i think)
Some perscription medicines are even reported to cause visual side effects IIRC

I often see masses of color while awake, before falling asleep.

After image effects can be seen w/o light being present as well.

Ray

 

[Photo Engineer]

I disregarded them for obvious reasons Ray.

PE

 

[Athiril]

Well I'd love to be able accurately reproduce imagery from my head instead of a camera!

 

[Hologram]

Three color holograms have been known for a few years, but doing it by the method cited here earlier is different in that he seems to have only 2 color lasers. See his offerings on the web page referenced earlier.

No, no. You can't do it with two wavelengths only. Be assured the Gentet/Ultimate full color holograms used to involve three lasers.
By the way, putting aside the recording material, the choice of recording wavelengths has a huge impact on color rendition.

The Denisyuk holograms are done with 3 lasers.

In any event, my experience with them which was limited to one or two views of some holograms, fell short of offering a full color spectrum from 3 lasers. The limitation that I saw is justified by looking at Figures 4 and 5 in the referenced article and Table 3 which shows the deviation (x/y) from the true colors. Just as a fluorescent light can appear "white" does not mean that there are uneven areas in the emission and that is particularly true in these examples shown in the figures and table.

The paper I referred to is a bit outdated (1998). Much progress has been done meanwhile.
More recent work can be found here: http://river-valley.tv/conferences/himm-2008/ - particularly Gentet's and Bjelkhagen's presentations.
http://river-valley.tv/color-holography-progress-and-new-recording-materials/

I do agree that the results of some of these researchers are quite striking, but fall short of what film or even digital can do. However, we are wowed by the 3D image and manage to downplay any color discrepancies.PE

Not sure about that...

 

[michaelbsc]

(Your statement can only be correct if you qualify it! )

There are several methods COLOR can be seen in the total absence of light.
A knock to the head.
Pressure on the eye ball
Dreams
Hallucination (schizophrenia, DTs (?), sensory deprivation etc.)
Direct stimulation of the brain by a neurosurgon (i think)
Some perscription medicines are even reported to cause visual side effects IIRC

I often see masses of color while awake, before falling asleep.

After image effects can be seen w/o light being present as well.

Ray

You left out migraine auras. Mine are purple, but their color seems to be individualized rather than generalized.

 

[Photo Engineer]

No, no. You can't do it with two wavelengths only. Be assured the Gentet/Ultimate full color holograms used to involve three lasers.
By the way, putting aside the recording material, the choice of recording wavelengths has a huge impact on color rendition.

I know that! However, Gentet only offers four lasers in two colors. That is all I was saying. Therefore, I cannot judge! He appears to be keeping the other laser to himself.

PE

 

[Ray Rogers]

You left out migraine auras. Mine are purple, but their color seems to be individualized rather than generalized.

Sorry! And to think, I have a yellow expanding blob thingy that obstructs my line of sight sometimes!
I am so bored of yellow. Purple sounds really good. Wanna trade?

 

[michaelbsc]

You left out migraine auras. Mine are purple, but their color seems to be individualized rather than generalized.

Sorry! And to think, I have a yellow expanding blob thingy that obstructs my line of sight sometimes!
I am so bored of yellow. Purple sounds really good. Wanna trade?

Only if you'll take the headaches with it.

I have a couple of friends who have recommended Topamax, but I still haven't tried it.



The purple is quite interesting, however. If it just didn't forebode such a miserable next few hours it would be almost as good as rose colored glasses!

 

[Ray Rogers]

Only if you'll take the headaches with it.
QUOTE]

No thanks, I'm good!



But,
Humm, do enjoy the Rose Garden

 

[holmburgers]

So I routed out a film holder to accomodate two sheets sandwiched together. I slid high grit sandpaper under the channels until I removed enough material to do the trick. A good time...

Anyways, putting two sheets in the holder, it is painfully clear that just taping the edges together is by no means an effective way to keep the screen & film in optical contact. They need to be flush or registration will be impossible.

I'm curious how you achieved this Mssr. Frizza??

Reading through Friedman's chapter on Tripacks & Bipacks gives a few suggestions of how to keep film in optical contact and yet easily separable. Various adhesives, soap, collodion, glycerine, etc... in the end he concludes that a spring loaded glass sheet is the best method.

You know, if you could just coat a panchro emulsion (Ron) on the back of the slide film or whatever your screen plate consists of, you'd be in business.

An early suggestion by a member was to just wet the two and that they'd stick quite well. I'm concerned that this would damage the emulsion and not to mention, when you do a pre-bath on film, a ton of sensitizing dye comes out. So I don't think getting them wet would be a great idea, but perhaps there is a better liquid. Alcohol perhaps? I read that alcohol will not penetrate gelatin.

Any advice would be appreciated. Once I figure out this optical contact part, I feel like the process will be complete.

 

[Photo Engineer]

The ISO 40 emulsion I gave here will work if properly sensitized and can be coated on glass plates.

Go ahead! Do it!

I'm giving that workshop in Jan at GEH. If you come, I will give you some side tips on doing this work and even run you through a make if you can stay longer than the course length.

PE

 

[holmburgers]

PE, that would be awesome! However, I think that making my way to Rochester would be difficult.

I'm a poor young man and I'll be busy in January skiing the Rockies! However, I'd be more than happy to send a screen to anyone who is set up to do it. And if they'd coat it for me, I'd even pay for such a service!

But hmmm, finally a justification to try emulsions... something to think about.

Do you have any recommendations for a water soluble and non-emulsion-detrimental adhesive?

 

[Photo Engineer]

Well, you see, you have set your time and financial priorities. This is the case generally when it comes down to the wire! Have fun skiing!

As for an adhesive? Gelatin is excellent. It can be permanent with a hardener or temporary without one and that latter one will release in the process.

PE

 

[holmburgers]

PE, of course. GELATIN! What could be simpler?!

Ok, what would you recommend for a formula? Maybe just make a carbon glop w/o sugar and w/o pigment. Like 1 part gelatin to 9 parts water?

I wonder how long it would take to dry? Heck... actually, it wouldn't even really need to dry completely.

And thank you, I will have fun skiing Though, making my way to Rochester is definitely on my list of things to do.

 

[Photo Engineer]

Gelatin coats best at 5% - 10% but you can go as low as 2.5% for some methods of application. Only you can determine this by experimentation. At 10%, if you wish to harden it, take commercial Glyoxal (40%) and dilute 1:9 to get 4%. Then use about 5 ml of that 4% solution in 100 ml of 10% gelatin. This will harden overnight.

Remember that depending on application method, you will probably need a surfactant.

PE

 

[holmburgers]

Well it should be as thin as possible... Photo-flo as the surfacant?

Perhaps for final mounting the addition of Glyoxal will be a good bet. It will probably allow me the time to register it visually, assuming its viscosity is low enough.

I think I'll try this when I get home!

 

[Photo Engineer]

Photo Flo is a fine non-ionic surfactant. In 100 ml of 10% gelatin about 0.5 ml or less should be enough.

PE

 

[holmburgers]

Whoa, thanks for the tip. I probably would've started out with wayyy to much.

 

[holmburgers]

Ok, last night I did a down and dirty test with gelatin. I used two junk sheets of slide film and long story short, they adhered together tightly/nicely and removed just as easily, with no residue. And it fit into my modified film holder. So... it'll work!

I used a 3% solution of gelatin, which seemed a little two runny perhaps, and set too quickly. Next time, I'm going to warm the glass plate that I did this on and try a thicker solution. I forgot to add photo-flo, so a few bubbles to boot, but all in all it was a proof of concept. Now I've got to figure out the particulars and oh yeah, then practice in the dark....

But man oh man, I'm excited

 

[happyjam64]

Just an idea here, what if one printed (via inkjet) an RGB or a similar array on the back of x-ray dupe film?

The potential problems I see with this is, 1. there might be an anti-halation layer, 2. the ink may not adhere to the base, 3. the film would have to be loaded emulsion side down (scratches), and 4. it would have an INCREDIBLY slow speed.

AFAIK x-ray dupe film is a direct positive film, so there wouldn't be a need to reverse process the film, and the film is also relatively cheap.