The Plugin Site

Doug,

Actually, you don't need a filter to do high pass. All you need is Gaussian Blur and Invert:

1. Copy the original layer into a separate layer
2. Place the copy layer over the original
3. Blur the copy layer using Gaussian Blur
4. Invert the copy layer
5. Set the transparency of the copy layer to 50%

Voila!

Interesting. But you get a more accurate Highpass effect if you additionally use the Linear Light blend mode in Photoshop. That blend mode isn't available in PSP, but the Normal blend mode will do, too.

Can you please share the URL about the lithographic derivation, Doug?

There is also an excellent article about the High Pass on Gamasutra:
http://www.gamasutra.com/features/20010523/hajba_01.htm

Paint Shop Pro 8 has a 5x5 Highpass and a Highpass plugin listed under the User defined plugin listing.