Autochrome Conversion



The Autochrome was the first commercially viable colour reproduction process. The Lumi√®re Brothers in France patented the process in 1906.  Grains of starch were stained red/orange, green and violet although the US patent does indicate other possible combinations of colours.

The grains act as colour filters so that the silver-based emulsion behind reacts accordingly.  After monochrome film reversal development, the glass plate is viewed through these filters and colour is obtained additively.

The manufacturing process continued from 1907 through to the early 1930s until subtractive film processes replaced it.

The viewed effect is that of a grainy image, not dissimilar to that obtained from very high ISO rated conventional subtractive film or a noisy digital image.

autochrome kodak
1915 color plate, screen (Autochrome) process

Aesthetically, the image resembles pointillist art which produces its colour effect in a similar way by dots of applied colour.  At the time, scientific theory proclaimed that all was made of atoms, tiny objects, thus art science and photography were unified.

This tutorial from Terry (who lives in a small village on the outskirts of Stoke-On-Trent in Staffordshire, England) will lead you through the steps to create an Autochrome image with Paint Shop Pro..

The Process


Choose an image to convert - the process seems to work quite nicely with landscapes but does an amazing job with portraits as well (as you can see from the image from 1915 above).

On the left is the original image and on the right is the image after the autochrome conversion.

autochrome original autochrome last
Original Image Final Image

It may be difficult to see what makes the images so different so here is a close up detail view of the sky and the top of a tree ...


autochrome detail


Step One - Split Channels and Add Noise



The first step is to split the image into it's red, green a blue channels by selecting Image > Split Channel > Split to RGB ...  To make working with the three channels a bit easier select Window > Tile Horizontally - now you have a good arrangement to work with.


autochrome split channel


Now we are going to add some noise to each of the split channels - Adjust > Add/Remove Noise > Add Noise ...

For a large image like this one  (3264 pixels X 2448 pixels) use the following noise settings.


autochrome blue noise
Blue Channel Settings

Random
70%

autochrome green noise
Green Channel Settings

Random
60%
autochrome red noise
Red Channel Settings

Random
50%


If the image is smaller then proportionally smaller noise settings will be necessary to maintain the good looks of the final image.  There is no formula for the noise settings - these are the ones that Terry suggested and they work well with this large file.

Step Two - Recombine The Channels



autochrome combine channelsThe next step is to combine the three channels with their new noise settings.

Makes sure that the Red Channel is in the red channel source, the Green Channel is in the Green channel source and the Blue Channel is in the Blue channel source.

The new layer will be called Raster 1.

One time I didn't and ended up with a really odd and very, very noisy black and white image.  It was puzzling for awhile.


Step Three - Levels Adjustments



The third step is to apply Levels on the combined image on Raster 1 using Red, Green and Blue rather than the composite RGB.  

Select Adjust > Brightness and Contrast > Levels ... this will require 2 different adjustments, one for Red, one for blue and nothing for green.


Red Channel Levels

Lowered to 109

Reduces red and adds a slight Magenta cast.  

This adjustment is a suggestion only - adjust your image to taste. 
autochrome leves red
Green Channel Levels

No change
autochrome levels green
Blue Channel Levels

Lowered to 100

Reduces blue and adds a slight Magenta cast.

This adjustment is a suggestion only - adjust your image to taste. 
autochrome levels blue


This is how the image looks before the final adjustments ...


autochrome post levels



Step Four - Average Blur



autochrome layers
Duplicate Raster 1 by right clicking on it and select Duplicate or go to Layers > Duplicate - whatever your preference.

Make the Copy of Raster 1 active and add some Blur using the Average Filter ...

Adjust > Blur > Average ... and set the Filter Aperture to 29 which is Blur High in the drop down menu in the palette.

Set the Blend Mode of Copy of Raster 1 to Color (Legacy) and the blur disappears.


The image is starting to look good - so - let's do some additional adjustments.

Go to Image > Negative Image and this is what you will get ...

autochrome negative image


It looks rather strange at this point, doesn't it but if the Opacity of Raster 1 is lowered to around 20% this is what happens ...


autochrome lower opacity


Now that looks better doesn't it?


Step Five - Adjust Brightness and Contrast



To give the final image that true Autochrome look the Brightness and Contrast needs to be lowered.  Each image is different and this is the best for this one ...


autochrome brightness and contrast


To produce the final image ...

autochrome final image


There you go - a really great autochrome tutorial from Terry - check out some of his other images here.  

The images grow on you after you do a few of them so give it a go!

I wrote a PSP Autochrome script and if you want a copy send me a message through the Contact page ...



Autochrome Comments, Questions and Examples!

This is a really interesting technique and we would love to see your questions or comments.

If you want to share your Autochrome results you can upload an image as well

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Autochrome

Autochrome is an additive color 'screen-plate' process: the medium contains a glass plate, overlaying random mosaic of microscopic grains of potato starch, with lampblack filling the space between grains, and an impermeable black-and-white, panchromatic silver halide emulsion.

thumb colors

The grains are a mixture of those dyed orange, green and violet, which act as color filters.[3] The plate is processed as a slide — that is, the plate is first developed to a negative image and then reversed to a positive image — and the starch grains remain in alignment with the emulsion after processing in order to allow the colors to be seen properly.

thumb tajmahal
Autochrome of the Taj Mahal.Source: The National Geographic Magazine, March 1921

To create the Autochrome plates, a slightly concave glass plate was coated with a mixture of pitch (crude pine sap), and beeswax. The starch grains, graded to between 5 and 10 micrometres in size, were coated on top of the plate.

The exact methods by which they were coated still remain unclear, although it is known that approximately four million grains per square inch coated the filter in a single layer. It was later discovered that applying extreme pressure to the plate would improve the quality of the image, as the starch grains would be flattened slightly, reducing graininess and transmitting more light to the emulsion.

Lampblack was then applied by a machine in order to fill the clear spaces between the grains. After this, the plate was coated with shellac. This served to protect the color mosaic and provided a flat surface for the emulsion, which was spread on the plate once the shellac dried.

The 1906 U.S. patent describes the process more generally: the grains can be orange, violet, and green, or red, yellow, and blue (or "any number of colors"), optionally with black powder filling the gaps.

(Source - Wikipedia)








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