Photochromic or photoreactive autochrome

jsmoove said:

Is it possible to digitally print an autochrome filter/plate such as:
https://cs.nyu.edu/courses/spring16/CSCI-UA.0380-004/slides/09/image-processing.html#/16
using photochromic or photoreactive ink (example: Inkodye) in an inkjet printer,
then expose an image using a projector with a UV bulb/blacklight bulb?
See: http://www.inkodye.com/help/advanced/projector
Would this work? Would each "pixel" of RGB be activated separately or would the UV just expose the entire thing?
I probably have my order mixed up about how the autochrome process works, but im curious to know if this would work at all.

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jsmoove said:

@jim10219 Oh I didn't notice they weren't making it anymore. I guess Solarfast then. Or any water based light sensitive vat dye. But I guess without the magnetic particles it wouldn't be possible. Photochromic inks are available in inkjet form, but they are reversible not permanent. My goal is to expose a color image on fabric. I don't know if there is such a thing as a one-layer panchromatic liquid light.
@nmp Hey. What do you mean by a blanket exposure? Yes you have it right, but instead of glass or plastic I want it directly on fabric. Are you sure a projector wouldn't work? Maybe a camera obscura then with the image on the outside? Im just curious about doing it the non contact printing way. Im mostly curious to know if the individual pixels would expose or if the whole thing would.
My idea was to project a color image onto a shirt, and the image would be transferred to the shirt. One layer.

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jim10219 said:

According to their website, inkodye is no longer made.

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jsmoove said:

@nmp Right, but something like a photochromic ink is exposed in about 15 seconds of UV light, so with a projector + UV bulb it might be a lot longer..but not too much longer I would think?
What I was thinking is covering an entire piece of fabric with small tiny RGB colours using a dye (which would be invisible at first) then exposing the entirety of the fabric with a color image.
I probably have it completely wrong though. The autochrome goes in the direction: light-->image-->color grains-->panchromatic emulsion, I think? So is it possible to do UV light-->image-->multicolor photochromic grain?
Im probably confused lol.

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jsmoove said:

@nmp Yes, just a regular ol' tshirt, with color images...patterns..styles, etc. Or multiple shirts at once depending on how far the projector is.
Sorry by inkjet I mean just any printer that you can load ink into that can handle fabrics.
You'd have a pre-printed shirt that you "activate" with your own projector, becomes visible once exposed.
I think monochrome UV image would work? Because itd just be the intensity of light that would activate the ink "pixels".
Though now that im thinking about it, I think the light would just hit the pixels and youd just get the bunch of pixels instead of your image.
Im unclear if this is true though.
I think something that can go from non-visible to visible permanently would be best, so probs not photochromic, unless an irreversible photochromic. I guess that is a photoreactive or photosensitive then?
The other way I had looked at it is, use the regular autochrome filter, but cover the shirt in a one-layer panchromatic liquid emulsion. Which I am not sure exists.
Definitely curious !

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• Inkjet inks do not need magnetic particles (a Laser printer by contrast does use a brush of magnetic particles to coat the electrostaticly charged paper to form the image).
• A lot of inks can work in inkjets but by no means anything, nor are all inks good. If there is a pigment for instance, it might clog a print head not designed for it.
• Inkjets work by having a tiny heating element vaporize a tiny bubble of ink in a channel which then pushes out a micro-drop of ink onto the page. It's a tiny amount but whatever you use cant be degraded by this kind of abuse.
• I think (?) there might have been some early confusion about something being panchromatic (it reacts to all visible light), and a dye being colored. Most black and white film is panchromatic (a red object will be as bright as a blue one), but produces a monochromatic image. By contrast Cyanotype media reacts only to UV light, but produces an image that is blue-green - You could expose it to blue-green light all day and not get very much of an exposure. For an Autochrome image you need a panchromatic B&W emulsion, and a non-photo sensitive color filter with small areas of each color. An inkjet in theory could print this filter if it could be done in such a way to stay sharp, and not get washed away with processing of the photo emulsion, etc. You'd in my opinion have more success trying to duplicate one of the other processes where the color filter was not bound to the emulsion (e.g. a Paget Plate - https://en.wikipedia.org/wiki/Paget_process ) because of these restrictions but that doesn't help with your fabric idea.
• There are not too many panchromatic technologies out there and they are hard to work with being sensitive to any light. Other than properly treated silver halide emulsions, there are some photo-polymers and not much else without huge exposures.
• For producing a color image from a color source by analog means, you'd need something panchromatic. Otherwise you'll be exposing each color through a negative/positive with light of a different color (usually blue/UV, like gum-bichromate or carbon transfer).
• An Autochrome (color filter on top of a black and white image) is very dark. Any color image made like this has to be either dark or very pastel by physics. Autochromes have to be back lit. Furthermore to get clean colors there has to be a tight correspondence between the B&W image, and the color filter. I don't think fabric (even say thin silk backlit) would hold hold this structure well enough to make a clean image. If not, to form a bright saturated image the image bearing substance has to be colored itself. To be as bright as possible, it has to be done in a subtractive color space (cyan, yellow, magenta) rather then and additive one (red, yellow, blue) as well. Finally to produce a final image from a camera if that is the goal it has to be a positive process (e.g. red light produces a product that reflects/transmits more red light) and much more light sensitive than a process that would work in an enlarger, or in a contact printer exposed to the sun.
• If you did try to use non-panchromatic emulsions for an Autochrome like end result you'd run up into the problem that dyes for your color filter (needed for viewing) would block the UV light you needed to form the image (Especially the yellow). You could expose through the back side, or try to use a different mask for creation and viewing but registration then becomes a huge problem.

• A sun bleached dye-destruction technology rather than an actual emulsion like the Utocolor process ( https://en.wikipedia.org/wiki/Utocolor ). The result would not be light fast though, and exposures would very long.
• Building up an image in layers using non panchromatic media somehow. Say sputter (small non-covering drops) some emulsion, expose a color separation with UV, dye the correct color and then repeat.

1. Processes where colors are produced by having multiple layers each of which produces an image in a component color to form the final image - This is how slide and negative color film work. The images are in some kind of negative color space, and the layers have to allow light needed to view upper layers (IE the layers need to resemble more a stained glass window or a watercolor, than a layer of house paint). These methods tend to be the most efficient with light producing the brightest images. The complexity is creating all these layers in such a way that they are robust and react correctly. Most film dyes are not exactly the right color for a perfect 3 color image for instance (its part of why slide film has the look it does).
2. Processes where the component colors are separated into distinct spots on the image in some kind of pattern larger than the wavelength of light but small enough to allow details to be seen in the image - The most famous of these was the Autochrome but there are many others - These are usually are done in a positive color space (Autochrome's was orange, violet and a greenish blue if I remember right as a compensation to insensitivity of the base emulsion to deep red light), though they can be done in a subtractive space by giving up on the maximum saturation of the image. So in general you could have a low intensity image with vibrant colors, or a bright image with weak colors, or some midway point. Autochrome chooses the former and relies on backlighting.
3. Processes that encode the color of light by recording interference patterns (light interactions on the order of the size of the wavelength of light) - The only one of these I know about is called a Lippman plate. These images are very restrictive on lighting an viewing angle, and the very fine structure producing the image is very delicate.
4. Processes where all the interactions happen within a single layer forming a mix of dyes of the appropriate color - Utocolor is a very rare example of this. The reason you've not heard of it is this method lost the color wars and didn't even have a brief moment of historical popularity. These methods would usually have to be t color space methods because all the dyes are mixed at once.

• Solook into modern methods for stabilizing dyes.
• Find better ways of making dyes temporarily more sensitive to light so that more stable dyes can be used or shorter exposure times may be achieved. This might involve temperature, UV exposure, etc in addition to the sensitizer itself.
• create a micro-engineered product that works by the action of light in a more complicated way (say grains of pigment coated in a photo-polymer of some sort).
• Engineer it some way so that some other property is manipulated by the action of the light (say solubility) so that you can remove the non image dye in some other way.
• Use some other photo sensitive component to increase sensitivity so that you're not relying on the destruction of the dye itself to make the exposure. This is how Cibachome worked but it was a layered product that required a lot of engineering to get the layers right.

Photo Engineer said:

Mark Osterman, of GEM, has told me that after examination of materials, and trips to France to look at details, no one has yet duplicated Autochrome as done by the brothers Lumiere. What is being done is not identical, but is a variant in each case, and does not approach the original in quality.
PE

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