Solaris X Window System Developer's Guide

Partially Transparent Alpha

Alpha values that are not completely opaque (1) or completely transparent (0) should be used with caution. Compositing operations with partial transparency yield the highest image quality only when a large number of colors are available in the DPS color cube and gray ramp. That is, image quality is best with a 24-bit TrueColor or 8-bit StaticGray visual, and image quality will be poor with an 8-bit PseudoColor visual. In addition, the performance of compositing operations is greatly reduced for partially transparent pixels due to the extra computation required in these cases.