CALPHA.IXP Copyright 1996
Written by Peter Watje
Internet   peterw@blarg.net
Compuserve 74453,225

CALPHA.IXP is an image processing routine that crops
the alpha channel based on a threshold and replaces 
it with a solid color.  If you are working with sprites 
this is a time saver.  It allows you to use antialiasing 
and them remove the outer antialiased edges all in one 
step instead of having to go through a two step process 
using a mask.


Basic Usage

1.  Add CALPHA.IXP to your video post queu after your KF scene.

2. Set the alpha threshold.  I usually use a setting of 60% to 70%.

3. Now choose your replacement color by clicking on the Replace Color 
button. Any pixels with a alpha channel value less than the threshold 
set above will be replaced with this color.

4.  Determine if you want the alpha channel altered.  If you set the
Strip Alpha button to on any alpha data that is less than the threshold 
is set to opace otherwise the alpha data is left alone.  Normally I leave 
Strip Alpha on.

5. Render scene.  Be sure to turn on Render Alpha from the render options 
menu otherwise the routine will not output anything.



Reference

Alpha Threshold determines the perecentage of the alpha channel to strip.

Strip Alpha Channel determines if the alpha data is also affected.

Replace Color brings up a color dialog.  Any pixels in the image with an 
alpha data less than the threshold will be replaced with this color.



About me

This IPAS routine was written fairly quickly (less than 2 hours) so I decided 
to release it as shareware.  I take no responsiblity for any damage that may 
occur from using this routine.  This IPAS can be distributed freely, however 
if you want to post this routine to a webpage, ftp site, buletin board, or 
anything similiar please email for permission first before you do so.


I also write commercial IPAS routines so if you find this routine useful you can 
support me by purchasing my other routines such as MAGNET.PXP from Digimation.


I have plans for several more routine both shareware and commercial listed below.

Displacement mapping AXP
Hair generator 
Keyframe database manager
Lip sync/facial expression tool

If you have any questions or suggestions feel free to contact me through my compuserve 
or internet account.


Known Bugs


None


