Greater Usability of GeneXus Applications with Themes (IV)

(04/11/2003-00:00)

When selecting transaction colors, the background color must always be considered. By Jorge Marmion

Ocular sensitivity depends on wavelength and reaches its peak at the 560-nm spectrum:

In order to be perceived at the extremes of the visible range, colors (blue and red) must be more intense than those at the central range (yellow and green). Text must have the maximum possible contrast with the selected background. Actually, black text on white background is the most effective option.

Do not use colors at the extremes of the visible spectrum simultaneously because the ocular lens has to constantly readapt and this causes visual tiredness.

A good contrast may be obtained by combining dark colors from the bottom half of the circle and light colors from the upper half of the circle.

Let us see, for example, a blue text on a yellow background:

We will now darken the blue (by diminishing saturation) and lighten up the yellow (by adding white):

Do not use adjacent colors within the circle simultaneously. Note the combination of red and orange:

- Avoid using light colors (saturated) from the bottom half of the circle with dark colors from the upper half of the circle simultaneously.

- Avoid adjacent colors whose only difference is a blue hue. Blue does not contribute to contrast and borders tend to be diffuse.

- There are no blue cones around the optical nerve, in the center of the retina. Therefore, avoid using pure blue (#0000FF) for text, very fine lines or very small figures, since they are difficult to see.

- If the cultural and thematic context is appropriate, blue is an excellent background color, especially on computer screens, because it helps turn the rasterization lines into more diffuse ones.

Jorge Marmion is author and director of the project that created the "DB-Examiner" software, chosen as one of the best 100 applications worldwide, by readers of the DM Review in 1998, 1999, and 2000. The software has been incorporated into the ERWin suite of products and has been distributed by Computer Associates under the name of "ALLFusion Data Model Validator." He is currently in charge of the Brazilian Institute of Friendliness and Usability (www.ibrau.com.br), and the Latin American Institute of Usability (www.ilau.org).

Greater Usability for GeneXus Applications Using Themes (I)

More Usability in GeneXus Applications with Themes (II)

Greater Usability of GeneXus Applications with Themes (III)

Greater Usability of GeneXus Applications with Themes (IV)

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