Step 4: Dealing With Perspective Distortion

The only way to truly eliminate this would be if your camera was on the same axis as the projector, however if this were the case it would be blocking the light so we'll have to try and work around this.

The simplest solution is to place your camera below the slide projector but up high enough so it is just out of the way of the image.

This will still result in slight amount of keystone distortion and you've got two choices to deal with it. The easiest way is to just crop the image and since the distortion is so slight you'd never notice (this is what I had to do), the other option is to correct it using the perspective or skew transform in Photoshop. I won't get into the specifics of how to do that but here is a link to an article that goes more in-depth about how to do it.

I ran into this problem for work when I had to digitize some x-ray films so I created an app for my iPad and iPhone and BlackBerry PlayBook to help me solve this problem. It's called ViewBox. Just wanted to share it with your readers.<br><br>You can read about it here:<br>http://www.forestcity.ca/viewbox/<br><br>or Download it from the app store:<br>http://itunes.apple.com/us/app/viewbox-dental/id504159417?mt=8&amp;ls=1
Excellent &quot;ible&quot;.&nbsp; I used the same idea myself a while back, but hadn't worked out a lot of the details.&nbsp; One thing I found that you didn't mention;&nbsp; with the camera below the projector, if you tilt the top of&nbsp; the projection screen forward it will reduce the keystoning (distortion) of the image in the camera.&nbsp; You want the screen to be perpendicular to a point halfway between the camera and the projector.&nbsp; You've made me want to dig out my old slides and do some more.&nbsp; Thanks<br />

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