Pictures of Keystone Artifacts

I have an old Panny 300 that I am using a pretty good amount of digital keystoning about (+10 on vert) and I really can't tell the difference between the keystoned and non-keystoned image. I believe the main downfall is that the image will not be as sharp. But just to clarify I am now using it in an a different arrangement than most. It is now being used in a poorly light controlled room so I tried to go as small as possible with the image to get the most light output on the image. I am only at 56" diagonal. The only issue I have is the image doesn't use up the complete LCD panel so the bottom half of the image is black / grey and it spills past the masking around my screen. It is pretty noticeable on my wall. My black levels in general are much greyer now than previously on my 92" screen

So in my case I am not sure if the small size is hiding the reduction in clarity or possibly the smoothscreen of the panny.

http://www.audioholics.com/reviews/p...d-installation

http://www.mcsquared.com/images4.htm

Using the digtal keystone control does not alter the distortion, it only crops the picture to make a rectangle. Here is a quote from Optoma's site.

Now for a word of caution: Digital keystone correction is not necessary if the projector is properly set up, and therefore, Optoma does not recommend using digital keystone correction unless the limitations of the room prevent proper set up. Keystoning is a mathematical calculation and therefore keystone corrected images will not be as clear and artifact free as images that are not keystoned. Distortion and other artifacts can occur around the edges of your image. Optoma's Pixelworks scaler is one of the best in the industry but no scaler is effective 100%. The best solution is proper setup.

Avoid keystonig if possible.

Bob

With all due respect, I'm going to have to disagree with this statement.
Turn on your projector, get a picture with some large text displayed and paused (text only because it is easier, but feel free to use someone's head or a building if you'd like) ... measure the width of that object.

Now, start keystoning.

Take some measurements along the way.

This object, be it a head - word - letter - building - whatever, is going to adjust in size depending on how much keystoning you perform. That, by it's very nature is altering and distorting the image.

On a side note, gwlaw99, a few years back I wrote an article about keystone correction. I had some nice examples of the image distortions. I even had some nice digital pictures of face close-ups that showed pupils of eyes completely disappear with keystoning.
I'll see if I can dig them up when I get to the office on Monday.

DISCLAIMER - I am not by any means stating that keystone is going to completely mess up a projected movie. I am just stating that it does, in fact, effect picture quality. I realize that some folks would never notice or be bothered by it.

There's no question that keystoning effects the picture. I own an Optoma DV10 all-in-one projector that I've taken to many places to show a movie. Because of less than ideal locations to place the projector, I've often had to use keystoning to 'straighten' up a picture. The problem is that to a newbie eye, a picture that needs keystoning looks ridiculous to many people. It's obviously not square and something is wrong. The problems apparent with keystoning, primarily moire patterns, are far less obvious to an untrained eye.

Now I personally can live with RBE, SDE and other projector problems, but I hate moire patterns. I usually keystone until the picture is relatively square but there are no moires obviously visible. This always makes the picture look better for most people. Nope, it's certainly not perfect, but when you have to use keystoning, there are few other options available.

Jim