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Color sequence

As the analysis in Section III reveals, temporal changes in the screen cost energy. When the screen changes color, the CPU consumes additional energy to generate data for the framebuffer, the framebuffer has to be then updated, and corresponding liquid crystals have to change orientation. The second experiment was designed to measure the energy of iPAQ1 for changing the screen from black to different colors. To eliminate the additional energy due to the LCD presenting different colors, it is turned off. Therefore, the experiment mainly accounts for the additional energy due to the first two of the three processes mentioned above. The data are presented in Table IX. It demonstrates the more the color changes, in terms of (R,G,B) components, the larger the additional energy consumption. This implies that a GUI with a constant color theme will be more energy-efficient than one that often changes color.

Table IX: Additional energy for showing and hiding windows of different colors on a black background
New color White Orange (RG) Red (R) Grey Black
Add. energy (EU) 8,000 7,900 7,500 7,700 7,400


next up previous
Next: Color patterns Up: Window properties Previous: Color
Lin Zhong 2003-10-13