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High pass filter?

Posted: Tue May 18, 2004 2:29 am
by Doug Semon
I found an interesting web site that describes a process that creates a digital representation of an effect I used to get in the darkroom called "lithographic derivation." The result looks like a line drawing, but with some detail.

The process requires a PhotoShop filter called "high pass." However, I use Jasc PSP, which doesn't include one. I've had no luck searching for a plug-in with parametric high pass.

Any suggestions? Free or pay, doesn't matter.

Thanks,
-doug-

Posted: Fri May 21, 2004 12:42 pm
by golloween
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!

Posted: Fri May 21, 2004 8:00 pm
by HaraldHeim
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?

Posted: Sat May 22, 2004 7:51 am
by Guest
There is also an excellent article about the High Pass on Gamasutra:
http://www.gamasutra.com/features/20010523/hajba_01.htm

Posted: Tue Jun 01, 2004 6:22 am
by Guest
Paint Shop Pro 8 has a 5x5 Highpass and a Highpass plugin listed under the User defined plugin listing.

Posted: Sun Jun 15, 2008 3:41 pm
by metalisrael
ok, this is an old thread, but it's awesome. thanks... nothing better than keeping it simple when it comes to effects