jitter image splitted on 3 videoprojectors? how do you do that?


Sep 10, 2009 at 2:26pm

Salut Igor!

> with bluring the edge of the images on the 2 or 3 screens

Cherche “softedge” sur Google ou sur le forum.


Sep 12, 2009 at 6:31pm

Last spring I made a patch/app that I call “Edge Blender” to span one HD movie across 2 screens with optional edge blending:
(forum wouldn’t allow me to attach the 550k zip)

screenshots (with lousy LCD projectors):

It handles arbitrary scaling and positioning and has an adjustable opacity contour for the blend (to deal with de-gamma and projector nonlinearities). It’s designed to be released as a standalone app but I never bothered. You can hack it up and use whatever parts you need.

I attached it below and included a preference file, some alignment test images, and more photo documentation.

It works fine but you need to use high-contrast DLP projectors because your black levels need to be very dark. See this excellent web page for an explanation of the basic idea:
also see: http://local.wasp.uwa.edu.au/~pbourke/texture_colour/edgeblend/

The forum thread where I stole the basic idea:


Sep 13, 2009 at 10:16am

wonderful !!!
thx a lot to share it.


Sep 14, 2009 at 8:18pm

If you are a fan of GLSL shaders and Matrox D2G’s, I came up with a solution for splitting a source to 2 screens and doing overlap/edgefade. The “tr.overlap3″ shader will do the same for 3 screens (matrox t2g, etc.). The benefit of this solution is that it all works in a single window/context.

Andrew B.

Sep 15, 2009 at 2:00pm

Wow Andrew, this is really cool!

Sep 19, 2009 at 9:36pm


Is it 2 screen or 3 screens blending ? To put one on top of the others ?

Merci anyway Wink


Dec 2, 2009 at 10:30pm

Hello , This tr.overlap is very interesting. I need some help to modify it for cylindrer image with a fade to close the circle. Somebody can help me to reed the shader.

May 10, 2010 at 9:38pm

Is someone have Andrew’s patch “edge blender” ?

Cause, the new forum..

thanks a lot!

May 10, 2010 at 11:59pm

I think this is it. Enjoy…

– Pasted Max Patch, click to expand. –
May 30, 2011 at 4:57am

My URL for “edge blender” has changed and I can’t edit my previous post. It lives here now:


For archive purposes, the patch is below (but I recommend downloading the ZIP since it has a prefs file, test images and setup photos).

– Pasted Max Patch, click to expand. –

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