Developers
AvantGo Channel Developer Guide

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Guidelines for color images on grayscale devices

Not all mobile devices support color images, of course. Many of the older Palm devices support only 4-color grayscale. While you cannot expect amazing image quality with four grays, images still come out looking fairly decent. Some people prefer to cater their images to this "lowest common denominator". If so, here are some tips for creating images for grayscale devices:

  • Just like with color devices, you only need to resize photo-realistic images and save them as JPEGs. Let the AvantGo sync server dither the image down to the appropriate color depth.
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  • With some photos, however, it helps to use Photoshop's "Unsharp Mask", which sharpens the image and emphasizes boundaries between two different color areas.
  • For line-art images, such as maps and logos, use Photoshop's "Posterize" command to reduce the image down to 4 non-dithering grays.
  • Before using the Posterize command with line-art images, it is usually a good idea to also use "Auto Levels" to make sure your image's levels are distributed evenly.

For examples of various images displayed on various devices, see Designing graphics for channel pages.



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