Cartography
GEO 225, Fall 2005
Geography & Meteorology Valapariso University

Fun with color models in Illustrator

When you start a new art board, Illustrator asks you which color mode you want to work with. If your map is going to be for the screen work with RGB, if for print CMYK. Since we're working with the screen let's choose RGB.

1. Draw a square and select it. Make sure that fill is selected so that when you make color changes the fill will change.

2. Open the Color Pallet. Note that the arrow on the upper right side gives you the opportunity to use different color models. For this exercise we will use the RGB, CMYK, and HSB models. (HSB is equivalent to HSV.)

To color something in Adobe illustrator select the object and then select a color for it on the color palette. The mixing space offers a quick and easy way to select colors, but often we want to be more exact and duplicate colors in different sections of our map. Different objects that are supposed to be the same color should be the same color. (Note, you should not use the paint bucket tool to apply color to your map. See the documentation for what the paint bucket should be used for. )

CMYK
CMYK is used for printing. If you have ever added ink to an ink jet printer you know that generally you use Cyan, Magenta, Yellow and Black ink.
3. Open up the CMYK pallet (using the menu revealed by the right pointing arrow)
4. Move all of the sliders to the left so that all values are 0%. What color do you get?
5. Now move all three sliders except for K to the right what color do you get?
6. Move the K slider to 100%. What color do you get?
7. How can you create a grey?

RGB
RGB is subtractive.
8. Move all the sliders to the left-0 What color do you get?
9. Move them to the right what color do you get?

HSB
Let's consider Hue, Saturation and Value independently.
Set the color pallet to use the HSB color model.

Hue
Notice that Hue is measured in degrees. This is like the circle on pg. 164 of Monmonier.
10. Set S and B to 100% and H to 0 degrees. What hue do you get?
11. Now set H to 360 degrees. What hue do you get?
12. What Hue do you get when the slider is set at 180 degrees?

Saturation (strength or purity of color)
13. If you have not already done so set the H slider to 180. Make sure that the B slider is set to 100%. To begin with the S slider should be set at 100%.
14. What happens when you move the S slider to 50%?
15. Reset the S slider at 100% and then set the Hue slider to 100 degrees for a nice lime green color.
16. What happens now when you move the S slider to 50%?
This illustrates one of the disadvantages of the HSV model as described on pg. 193 in your text. Different hues having the same saturations do not have the same perceived saturations.

17. What happens when you de-saturate the color by moving the S slider to 0%?

Value (or Brightness)
18. Now set the H slider to a nice purple at 275 degrees, not that you can see it now.
19. With S at 0% move the B slider to 50%. What color do you get?
20. What happens if you move the H slider?
21. Move the H slider back to 275. Now what happens if you now move the S slider to 100%?
22. What happens if you move the B slider all the way to the right at 100%?
23. What happens if you move the B slider to 15%?

24. Now let's illustrate the other drawback of HSV. Different hues having the same value will not all have the same perceived value.
Set your B slider to 50%. You should have a purple color. Now set the H slider to 175. Does this greenish color seem darker or lighter in value than the purple? Lighter

25. How can you produce pastel colors using the HSB sliders?

26. How can you produce grey tones tinted with a hint of color?

27. Go to the Color Brewer web site and play around with it to see how it can be used to choose color schemes for your maps. http://www.personal.psu.edu/faculty/c/a/cab38/ColorBrewerBeta.html

One other note: The exclamation point inside a yellow triangle symbol in the color pallet indicates that you have selected a color that cannot be printed using CMYK inks.