GEOG 486
Cartography and Visualization

Part V: Creating Custom Colors

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A. Download Lesson Data

Color_practice.zip (147 KB)
This download includes several ArcMap documents that you will use for practice.

B. Perceptual Dimensions of Color and Color Spaces

In Lesson 1, Part IX, I introduced the topic of color spaces. I noted that a color space is a framework for describing color systematically. Before you return to work on your map, I want to provide more detail and some practice activities related to these topics.

Concept Gallery

Learn more about color spaces in the Concept Gallery.

Now that you have reviewed some literature on color spaces, I would like you to have some practical experience. This is a lead in to understanding how one might mix new custom colors.

  1. Launch ArcMap and open \\Color_practice\lightness.mxd. This map document is a simple grid of 100 cells (most of which have no symbol). The orange cells are independent objects that can be moved around in the space. Cartographers often use lightness to represent amounts of something - light is less, dark is more.
  2. Make sure that the map is displayed in the Data View and then click the Full Extent tool.
  3. Using the Select Elements tool, click and drag the orange cells to the lower row. Arrange them from light to dark.

    Click here to view result.

    RESULT:

    Lightness ramp, from light to dark.

  4. Open \\Color_practice\saturation.mxd. Save the changes to lightness.mxd if you like. Saturation can also be used to represent quantitative data. Map readers, however, are less able to see numerous saturation steps.
  5. Using the Select Elements tool, arrange the color cells on the lower row in order of saturation.

    Click here to view result.

    RESULT:

    Saturation ramp, from desaturated to saturated.

  6. Open \\Color_practice\two_dimensions.mxd. Save the changes to saturation.mxd if you wish. The view in this map is like that of a Munsell color slice, showing color space in two dimensions, lightness and saturation. In this next practice map you will arrange cells along both of these axes. I have positioned the corners for your reference. Arrange the color cells so that lightness varies vertically and saturation horizontally.

    Click here to view result.

    RESULT:

    Variation in lightness and saturation.

C. Mixing Colors in RGB and CMYK

For most projects, cartographers will mix colors in one of two common color spaces. RGB is used when the final product is intended for on-screen viewing. CMYK is used for printed documents. Remember from the concept gallery that these two color spaces can be represented as a cube. Further, the cube can be simplified to a circle that effectively shows the transitions between hues.

A graphic drawing of a color cube
Figure 2.5.1 A color cube.
Credit: Amy Griffin
A graphic image of a color circle
Figure 2.5.2 A color circle.
Credit: Cynthia Brewer

Notice that the primary hues from each color space end up being secondary hues in the other. For example, when mixing red and green in RGB space the result is yellow.


An illustration to show the result (yellow) of the mixing of red and green in RGB color space.
Figure 2.5.3 The often unexpected result of mixing Red and Green in RGB color space.
Illustration by Cynthia Brewer

Another important point to remember when mixing colors is how to control lightness. Recall from Lesson 1, Part IX, that RGB space is additive, meaning that 100% of these three primaries together create white. CMYK space is subtractive, creating black. In practice, this means that to create a darker version of the yellow in the previous figure, you would mix smaller amounts of Red and Green - 200R 200G, for example. The reverse is true when mixing CMYK - more of the constituent hues will create a darker result.

Now, some practice.

  1. Open \\Color_practice\mix_cymk.mxd. You have five tasks to complete. Each layer in the Table of Contents corresponds with a row on the map. Each row has at least two cells pre-colored for reference.
  2. Expand the layer called L1H (Lightness, 1 hue), and click on the symbol for data value 12. The object for this first row is to create a lightness sequence between the end cells.
  3. In the Symbol Selector window that opens, click on the Fill Color: drop-down menu. Choose More Colors...
  4. Click the drop down arrow found in the upper right corner of the Color Selector window and choose CMYK Sliders.
  5. Use the sliders to mix a new color for this data value. You may want to first look at the CMYK values for cells 11 and 15 to get a sense of the range. You also may want to consult http://colorbrewer2.org for clues on how to move through a color space effectively (for sequential, qualitative and diverging schemes).
  6. Repeat this process to mix colors for the other two gray cells in the row.
  7. When ready, move on to the other rows on the map. Notice that instructions for a color sequence appear above each row.

    Click here to view result.

    RESULT:

    mix_cymk.mxd results.

  8. Open \\Lesson3\practice\mix_rgb.mxd. Save the changes to mix_cymk.mxd if you wish.
  9. This is the same process as before but this time mix your colors using the RGB Sliders.

    Click here to view result.

    RESULT:

    mix_rgb.mxd results.

D. Apply These Topics to Your Map

Now for the challenging part. You have read about color spaces and practiced mixing custom colors. Given what you now know it is time to turn your attention back to your reference map. For our scenario, you can assume that the final map will be a printed document.

  1. Open your Lesson 2 map document. Save the changes to mix_rgb.mxd if you like.
  2. Mix new CMYK colors for the features on your map. Remember from the Visual Hierarchy concept gallery item, that colors are an effective way to create figure-ground relationships among features.

E. Save the Map Document

That's it for Part V... and Lesson 2.

You have just completed Part V which dealt with color spaces and creating custom colors, and week 1 of this project. Next week you will create a multi-frame layout and explore labeling and typographic customization.

If you have any questions, please post them to the Lesson 2 Discussion Forum.