Did you know that transparency in GIF and 8-bit PNG images is supported as of Designer and Acrobat/Reader 8.0?

If you have an image that has a transparent area in it (perhaps you have an odd-shaped logo which you want to place on a colored background in your form), you can save it as a GIF or 8-bit PNG with a single color indexed as transparent.

There are various PNG formats: 8-bit, 24-bit and 32-bit. The 8-bit format is supported and uses an indexed color table in which colors may be marked as transparent (only one of which is supported in Designer/Acrobat/Reader). The 24-bit format is also supported and provides true colors (non-indexed) but no transparency. Finally, the 32-bit format allows for varying degrees of transparency (i.e. an alpha channel) within the image but is not supported at this time.

The GIF format is at most 8-bit and uses an indexed color table in which colors may be marked as transparent however Designer/Acrobat/Reader only supports one transparent color within the color index.

Updated: May 26, 2009

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Posted by Stefan Cameron on March 9th, 2009
Filed under Acrobat,Designer
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