My take on additive and subtractive color theories, a Photoshop color correction method, (3-click color) and a few odds and ends related to correctly printing from a digital photographic file.

1. Mr. Pixel’s Color Theory & Color Correction Tutorial
© Michael E. Stern
Build A Better Photograph dot com
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2. Mr. Pixel’s Color Theory Primer & Color Correction
Tutorial
Color Models
Color Modes
Color Numbers
Color Correction
© Michael E. Stern
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818-422-0696

3. Color Theory
Additive Color - Transmissive
Subtractive Color - Reflective
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4. Additive Color Theory
RGB
Red, green and blue wavelengths of light are added to black
and creates the colors our brains perceive.
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5. Additive Color Theory
RGB
An equal RGB mixture of additive light produces neutral
gray values. An unequal RGB mixture produces color.
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6. Additive Color Theory
RGB
Monitors
Projections
Sensors
Film
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7. Subtractive Color Theory
CMYK
Varying percentages of cyan, magenta and yellow inks are applied to
white paper. This subtracts from the white paper.
If the percentage is balanced, gray is the result. If the percentage is
unbalanced, color is the result.
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8. Subtractive Color Theory
CMYK
Theoretically equal amounts of cyan, magenta and yellow ink produce
neutral gray.
Inks contain impurities. These impurities produce browns instead of
grays.
Black ink is added to mitigate this issue. “K” identifies this ink. CMYK.
© Michael E. Stern
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9. Subtractive Color Theory
CMYK
Lithography is the prime example. Lithography is great technology but
there are two key issues to take into account as files are prepped for
printing:
1) Gamut. The range of reproducible colors.
2) Dot Gain. The amount of ink absorption.
© Michael E. Stern
Build A Better Photograph dot com
818-422-0696

10. Subtractive Color Theory
CMYK
1) Gamut is adjusted by the 3-click color correction method.
2) Dot gain is controlled by sharpening.
We correct files for the limitations of the chosen output technology.
© Michael E. Stern
Build A Better Photograph dot com
818-422-0696

11. Subtractive Color Theory
Gamut
Lithography and other forms of printing have limited reproduction
capabilities relative to the color range available in a digital image.
16.7 million theoretical color choices are available in an 8-bit image and
over 2 billion colors in a 16-bit image.
Depending on the method used to define and measure ink gamuts, there
are between 500,000 and 1.5 million color choices using CMYK.
© Michael E. Stern
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818-422-0696

12. Subtractive Color Theory
Dot Gain
The ink dots spread and flatten upon impact causing a loss of sharpness
and color fidelity.
There are many ways to sharpen a file. The Smart Sharpen Filter is a
good beginning method for sharpening images.
© Michael E. Stern
Build A Better Photograph dot com
818-422-0696

13. Subtractive Color Theory
CMYK
Newsprint
Magazines
Posters
Ink-Jet
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14. Color Relationships

15. Color Models
Describes Color Numerically
RGB - Red - Green - Blue - Light
CMYK - Cyan - Magenta - Yellow - Black - Inks
HSB - Hue/Color - Saturation/Richness - Brightness/Dark or Light
LAB - Lightness - A (Red/Green) - B (Blue/Yellow)
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16. Color Modes
Assign Values
an intensity value - RGB
an ink percentage - CMYK
how colors look to the human eye - L*A*B
256 shades of gray - Grayscale
black or white- Bitmap
256 colors - Indexed
3 channel grayscale for specialized printing - Multichannel
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17. Printing
Reproducible Shadows
Reproducible Highlights
Rendering Intents
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18. Printing
The best results are achieved by running ink density tests
and creating custom paper profiles. But if you don’t want to
go to the trouble...
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19. Printing
...then the 3-click color method is an excellent alternative.
This method sets the shadow and highlight endpoints to
match the shadow and highlight gamuts of a printer and
paper combination.
Also known as “setting the endpoints for output.”
© Michael E. Stern
Build A Better Photograph dot com
818-422-0696

20. Printing
Tutorial
3-Click Color
Adding Noise
Rendering Intent
© Michael E. Stern
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21. Printing
The following method works on any digital image. Some digital images work well with
the 3-click method while some images work better with a 2-click method. Experience
will dictate which method is best for a particular image.

22. Printing
Select Threshold from the bottom of the Layers Panel
by clicking on the half black, half clear icon.
This is the infinitely editable Threshold Adjustment
Layer.
This is good.

23. Printing
Make sure you can see the Info Palette. Drag the Threshold’s slider all the way
left and slowly drag back towards the center. When the black areas begin to
appear, stop. With the Color Sampler Tool selected, click on this area.
What are the values in the Info Panel?

24. Printing
Drag the slider all the way to the right and slowly drag back towards the center.
When white areas begin to appear, stop. Click on this area. Note the numbers in
the Info palette. These pixel values are 254-255.
After you click OK, turn off the Threshold Adjustment Layer in the Layers Panel.

25. Printing
Setting target shadow and highlight values
Shadows Highlights
Open the Curves Adjustment Layer the same way you opened the Threshold Adjustment Layer.
One at a time double-click each of the 3 eyedropper tools. The Target Shadow and Target Highlight
Color dialog boxes open. In the RGB boxes and with the Shadow Eyedropper active, input 13 for
the shadows. Click OK. Do the same for the highlight numbers. Input 247. These numbers will vary
for different printer, paper and ink combinations. In this example the percentages are 5% and 97%.
Middle gray is pre-set to 128. Do not change this number.
Notice how the circle changes its’ position on the scale at the far left of the large red box.

26. Printing
When you have completed this step, click OK. Click Yes if you also get this dialog box.
Look and you will see the Curves Adjustment Layer floating above your Threshold
Adjustment Layer and Background in the Layers Panel.

27. Printing
Shift + Command (PC - Control) + N will bring up this dialogue box.
Make note of the settings and click OK.
Turn off the Curves Adjustment Layer.
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28. Printing
Set the layer’s Blend Mode to Difference.

29. Printing
Both adjustment layers off. Difference and Background layers on. Wax on. Wax off.
Black is in reality middle gray because of how the Difference Blend Mode functions. The
gray pixels in the Difference layer cancel out the gray pixels in the Background layer
that are in registration with each other. Black is the result. Or close to it.
This is a way to identify where the middle grays are in an image. With the Eyedropper
Tool selected, (3x3 or 5x5) click on one or two target areas to set the point. Use the Info
Panel to monitor the targets. Try to get as close to equal as possible in all three
channels. This is important.

30. Printing
Turn off the Difference layer and turn Curves on.
Threshold can be deleted.
Re-open Curves by double-clicking its’ thumbnail icon.

31. Printing
Highlight
Mid-Tone
Shadow
Select the shadow eyedropper and click on point one. Select the highlight eyedropper
and click point two. Repeat for the middle eyedropper.
That’s it. 3-click color at its’ finest. Experienced users can set the shadow and highlight
endpoints by eye. If an image contains gray, skip the Difference Blend Mode layer steps
and click on the gray area with the middle eyedropper tool.

32. Printing
An optional step with the Curves Adjustment Layer: select the mid point at the center
of the diagonal line. In the Input box type 128 if it’s not already set. Reducing the
Output number will darken the image. Increasing the Output number will lighten the
image. This is determined by taste and experience.
I move in increments of ten. I’m usually ten up or ten down. Highlight the small black
square by clicking on it. Hold down the shift key (while pressing the up or down arrow
key) to move the point in increments of ten.

33. Printing
Before
After

34. Adding Noise
The Histogram may look like this after 3-
click color. This is called penciling or
combing. Click the refresh button to update
the Histogram. This button will disappear
after refreshing.
Gaps represent missing information. While
the file may appear OK on screen, banding
or posterization will most likely show up in
print. To prevent this, add noise (random
pixels) to the file on a separate layer.
Michael E. Stern
PHOTOGRAPHY EDUCATION CONSULTING
CyberStern.com

35. Adding Noise
Make a new layer and input the settings
shown here.
Go to the Filter menu, select Noise and then select Add Noise.
© Michael E. Stern
Build A Better Photograph dot com
818-422-0696

36. Adding Noise
2-3% for the amount. Make
sure Distribution and
Monochromatic are set
accordingly.
Click OK.

37. Adding Noise
Before
© Michael E. Stern
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38. Adding Noise
After 3-click color
correction, noise
added and a
histogram refresh.

39. Rendering Intent
Rendering intent aims to preserve numerical values,
saturation levels or perceived color relationships.
Perceptual is the preferred choice for photography in
that by preserving color relationships one perceives a
properly printed image.
Colormetric aims to print colors per the assigned
values in an image. When a color is out-of-gamut, the
next nearest color is substituted. Usually a reject print.
Saturation aims to preserve the richness of colors at
the expense of accuracy and numbers.
These are VERY simple explanations.
© Michael E. Stern
Build A Better Photograph dot com
818-422-0696

40. © Michael E. Stern
Build A Better Photograph dot com
818-422-0696