Secrets of Digital Photography
V6 iNovaFX Actions!    
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All photos by the author.

Repeatable Color!

Undocumented Feature

One thing that the chemical darkroom had was precision. Temperature control, chemical control and color control were vital to getting repeatable results. But no matter how hard you worked at it, the term "repeatable" was to be taken with a grain of salt.

Now digital darkrooming achieves what better-living-though-chemistry did not--true repeatability. So it's time to have tools that address that goal.

In the V6 Nikon eBook you will find a set of actions that help. At right is an example of an image with and without a 10CC Red color correction added. The original, neutral scene is on the right.

Simply running the iCF-CCFilters Action sets you up with three layers of filtration in Yellow, Cyan and Magenta plus a Curves Compensation layer. Yet the image looks no different from when you started!

Check the Layers window of Photoshop. There they are, behaving like gels do when placed underneath a slide, tinting its light source. Since they are colors with density, Curves Compensation is needed to recover full tonal range.

The default strength is 10 % which gives the result seen on this test image.

It isn't calibrated to the CC standard of Kodak Wratten Filters, but it is close. In the nomenclature of this iPAF* the "CC10" stands for a 10% Color Correction in the direction of the default mixture.

When the stack first appears, all colors are switched ON, but here you see the Cyan layer switched OFF (the eye icon along the left) to allow Magenta and Yellow to add up to Red. With all layers ON, there is zero effect, since the three colors add up to complete neutrality. With all of them ON, the filtration is a simple 10% reduction of every pixel value on display.

To get a distinct color effect, at least one of the three color filter layers will have to be off, but the densities of the remaining layer(s) are your controlling variables. Default is 10% each, but you can make them any density you wish with the Opacity control in the top row of the palette. As you make changes here, the image will update showing you the effect. You must select and highlight each layer in turn to produce the correction.

Just so there is no confusion, you could make the Yellow layer stronger and the Magenta layer weaker, causing a more gold CC effect, etc, but adding ANY amount of the third color layer merely introduces a neutral density effect as strong as the percentage value of the weakest layer. If you had adjusted things and saw Yellow 10%, Cyan 5% and Magenta 15%, you could simply remove 5% from each making Yellow 5%, Cyan 0% (or OFF) and Magenta 10%, producing the exact and precise same color effect after appropriate Curves Compensation layer adjustment.

That upper Curves Compensation layer lets you adjust the exposure fine tuning once you have the colorimetry to your liking. Here's the curve used in this example. Not very curvy, being a straight line from black in the lower left to an adjusted white point pulled somewhat off the upper right white position. (Yes, we could have used the Levels control, but our preference is to use the more graphically demonstrative Curves control.)

You adjust this from its default setting by dragging the white point around from left to right while observing the density change to the image. Of course, if you wish, you can make more elaborate Curves control settings.

The default density of each filter layer being 10% adds up to a total overall dimming of the image by 10%. Meaning that dimming the white point of the image by 10% would bring it back to unity with the original. In Curves control numerology, that equals 10% of 255 or -51 units. Also known as an input/output number of 204 which is shown here. But the Cyan channel is switched off, so it really should be about 2/3 of the differential number making an adjustment of the white point of only -34 or 221. So this test image is slightly OVER compensated. Don't worry, I'll get the hang of it...

As with many iNovaFX Photoshop Action Filters, experience will be helpful. Try both large and small color tweaks to your images with this Action and by the time you've spent a half-hour with it, your arsenal of color image manipulations will have grown. You'll get the hang of it, too.

Two versions are provided, one for use with 8-bit/channel images and another for use with 16-bit/channel images. I prefer the latter especially with the new Photoshop CS which is more 16-bit savvy than PS6 and 7.

Once you have tinted the image with the amount of color compensation you wish, flatten the image and save it under a new name, leaving your original untouched.

* iNovaFX Photoshop Action Filters.

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