ixel.

<p>Before Netpbm 10.25 (October 2004), <b>pamcomp</b> did not
recognize the transparency information in a PAM image -- it just
ignored it.  So people had to make appropriate alpha masks in order to
have a non-opaque overlay.  Some Netpbm programs that convert from
image formats such as PNG that contain transparency information are
not able to create RGB_ALPHA or GRAYSCALE_ALPHA PAM output, so you
have to use the old method -- extract the transparency information from
the original into a separate alph