Correcting Distorted Images

Written by
  • Shelagh M.
  • 11 years ago

Learn how to counter the keystone effect.

You’ve set up your projector but your image is distorted into a trapezoid shape rather than a square. Known as the keystone effect, this problem happens when the projector is not properly aligned with the screen.

The keystone effect can be frustrating and distracting. Whether you are watching a film or giving a presentation, looking at an off-angle image on screen is no fun.

How to correct


The old school approach was to prop up the projector with books or furniture to correct the angle for a proper projector image. Today’s current projectors are a bit more sophisticated but the principal remains the same: Correct the angle.

You can correct keystone problems either manually or using the keystone correction, a feature most projectors now have.

Manual correction

keystone_effect_Correct_projector_placement Physically adjusting the lens so the projectors is at either a higher or lower angle often solves the keystone problem. Try tilting the projector up so the projector image is higher on the screen or moving it further away from the screen. If the projector is mounted on the ceiling you may have to add an extension to the mount that allows you to lower the projector. Manual adjustment is sometimes the easiest way to correct keystone problems.

Digital keystone correction


At times you will not be able to control your presentation space, particularly if you are on the road with your projector. This is when digital keystone correction comes in hjandy because resizes the projector image so it appears square.

Horizontal vs Vertical Correction

A fixed keystone correction allows the projector to shoot upwards so tilting the projector is not necessary. Your angle for correcting the keystone will be listed on your specification sheet or in your use manual. Projectors will also vary at how much correction they can provide. Vertical keystone (up and down) corrections vary between 12 to 35 degrees of correction. Some projectors have a default setting of 50, which means no adjustment has been made. Horizontal keystone adjustment is more difficult to do so not aa popular; although some of the higher end home theater projectors are offering this feature.

Use digital keystone correction as a last resort since it involves scaling the projector image and this can create visual distortions. It doesn’t create the ideal picture quality especially with graphics and charts, which can be an important feature in business presentations.

Setting up your projector correctly is the best way to solve the keystone effect.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.