| I think the idea below is a really good one- in fact there were processes like this that used a pre-made color screen to expose the plate through- this was then taken off- the plate was developed and printed as a positive- then the color screen re-registered with the positive. The advantage here was that if the image was mediocre- the very expensive color screen could be re-used for another image. The color screen could be lined up with various good images made with that particular screen. ( I'm not sure the manufacturing process could duplicate the color screen so exactly that they could be mixed and matched later on ) These screen processes usually used a machine to rule lines onto a thin glass plate using red green and blue transparent medium (inks)? John Jolly of Scotland did this first.
The Lumiere Autochrome was different- it used transparent starch grains which were dyed cyan magenta and yellow.... These were randomly dusted onto a plate- then a SECOND layer of these grains was added... This means that cyan over magenta made a BLUE grain, yellow over magenta made a RED grain and cyan over yellow made GREEN grain. From the information I have garnered many years ago- this was how it was done- so everyone is correct- it used RED GREEN and BLUE filters - but what they could not see was that it was made up of the 2 layers of the CMY grains. Of course there were "errors"- some of the cyan , magenta and yellow grains layered over another grain of the SAME color.... this is partially what lead to the rather odd and desaturated look of Autochromes - I had always thought this was due to aging- but is inherent in the process itself. Another unique property of Autochromes was what I call worm paths.. these were short squiggly lines in the emulsion. My initial theory in seeing these was that bugs liked and ate certain colored grains-- it looked just like the path a worm travels when eating say a wooden desktop. Actually- I realized there is nothing wrong- no worms- it is simply that the plates dusted randomly are not random- a number of say cyan and yellow grains fall over each other- in a meandering line... the brain sees this pattern as a green meandering worm path as it is programmed to pick up patterns.
DIGITAL AUTOCHROMES- theory...
I spent a number of years thinking about how to do this... and over time it dawned on me that I had everything in PhotoShop that the Lumiere Brothers had to now make digital autochromes. I will provide a detailed method soon- but this much info is plenty for the more experienced of you to try this and see for yourselves if it yields a true "Autochrome Digital" effect...
My digital method of making AutoChromes breaks the image up in PhotoShop into CMYK, and I randomly add monochrome grain ( add noise, gaussian)to each of the CMYK layers. Go ahead- be fearless- really add a LOT of noise grain - more than you think would look pleasant- the grain will be in three layers and cancel itself out quite a bit. Then you blur the layers a little bit --- separately ---to mix the grains up a bit. BTW this method even reproduces the "worm paths" as I call them. To really make the final product an Autochrome- print the image with an inkjet printer on transparent media such as Pictorio OHP and display on a back-lit lightbox. Richard Vallon Jr. 504 905-1725
On Aug 29, 2007, at 9:32 AM, Gawain Weaver wrote: You can do it with red, green, and blue sharpie markers and any panchromatic emulsion. Your RGB lines won't be as fine as the grains of an autochrome (which range around 10 microns) but it's the same principle. Or as has been suggested, you could make a screen in photoshop with RGB dots (or lines, or squares, and hexagons- it doesn't really matter) as small as your printer can handle, and use that as your screen. Just shoot the image through your RGB color filter, then reversal develop (or develop and then print a positive on film-- which would mean you could make multiples), then re-register the RGB screen with your positive and voila, you have your own additive screen plate! Not an autochrome exactly, but close enough, and good for a classroom.
Gawain Weaver
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