Can someone explain autochrome....

[Photo Engineer]

JSMOOVE, I'm not sure about the latter, but the former reference is not correct. Steve uploaded examples.

PE

 

[Lachlan Young]

JSMOOVE, I'm not sure about the latter, but the former reference is not correct. Steve uploaded examples.

PE

https://www.photrio.com/forum/threa...ufaycolor-autochrome.63179/page-4#post-898861

Is this the post/ thread in question?

 

[jsmoove]

@Lachlan Young Thankyou for your detective work!! Am checking out now.

 

[Photo Engineer]

Thanks Lachlan.

 

[nmp]

@jnanian Thanks for the link! I think I was a bit misinformed in how the process works, I don't actually need to make any autochromes myself...was just more curious as to how they worked I found Ianvaag's explanation broke it down for me pretty good. I also found a good breakdown of color photography in my internet journeys last night:
http://dhlab.unibas.ch/documents/archive/color_photography_history.pdf
What I've been most curious about though is if it is possible to project an image onto a one-layer only color emulsion/material, that's sortof why I was curious to learn about the autochrome....was so that I might be able to digitally recreate the filter, and project onto a panchromatic emulsion.
I did find: http://proposal.ducr.u-tokyo.ac.jp/cgi-bin/ccr_usr/EN/detail.cgi?num=3678
A bit hard to understand for me, but would this type of emulsion work for such a thing?

I made this highly simplified schematic to help me understand the principle behind Autochromes....if it is useful.



It also occurred to me that ironically modern-day LCD displays work on a very similar principle as the century old autochromes. The difference is that in the case of autochromes, the light intensity regulation is done by a permanent layer of silver particles and the filter layer is a random distribution of colored starch particles. On the other hand, in an LCD screen, the light modulating is done by electrical stimulation of liquid crystal molecules between polarizers and the filter layer is made of photolithographically defined grid of pixels each consisting of sub-pixlels made of red, green, and blue pigments. I wonder if one can take one of those filter layers from an LCD display (perhaps an old iPhone) and use it as a filter substrate for an autochrome.

Regarding the U of Tokyo proposal, I can say that it does look like, if works as described, one should be able to make a color image from a single color exposure since it claims that "when exposed to light of a certain color, the exposed portion takes on a color similar to that of the light." However, the effect is still temporary so the image is lost gradually once the exposure is stopped. So the question is how do you capture the "fleeting" image permanently. Also this is research material, not something a hobbyist can dabble without considerable knowledge of material science and physics, not to mention substantial resources.

:Niranjan.

 

[Photo Engineer]

I should point out that the use of TiO2 as a light sensitive medium has been known since the '60s and was once used as the basis of making the first color electronic copies at Kodak (among others). We called it Electrocolor, as an electric charge was used to reveal the image. No silver was involved, and the image was not "digital".

PE

 

[jsmoove]

@nmp That's a great breakdown. Much easier for me to understand in layers or direction like that.
Yeah the same thread that Lachlan linked they are talking about using LCD's too.
UofT proposal : I read it the same way, if that's the case that's pretty amazing and im interested in knowing if its a single layer emulsion, the silver and the TiO2? I read that its temporary, but apparently can last up to a day or two? That is the question! Maybe in the near future you'll have something like this, but with a fixer for it?
Yeah im just a hobbyist. I find it all fascinating though.
@Photo Engineer Huh, that's interesting. I will check this out, sounds really cool.

 

[jsmoove]

@Photo Engineer Do you mind going into detail about this electrocolor paper/film and the electric charging process? I cant seem to dig up much...maybe im using the wrong terminology? Was it like an electrophotographic paper?

 

[Photo Engineer]

There are many patents on file to Kodak on this subject. It has been used as a method of producing analog color prints electronically. Basically, the TiO2 is coated on a support and sensitized with a variety of chemicals and then charged electrically and exposed. This is similar to current color copiers. It is sequentially exposed and treated with a special dye, and a color image appears. This is vague to me because it all took place nearly 50 years ago and was abandoned for a variety of other methods including Dye Sublimation which was used in Kodak color printers for years.

PE

 

[jsmoove]

@nmp @Photo Engineer
So I found: https://sci-hub.tw/10.1039/b416139d
So to me it sounds like you could project an image, but obviously once you take it out of the dark it wouldn't last too long before it disappears.
Not sure if I have that right. I think so though, when they say rewritable paper + paints.

 

[Photo Engineer]

The images generated by the Kodak method were made permanent by use of dye deposited imagewise wrt the exposure.

PE