keystone correction

It allows the edges of the projection are completely vertical when the picture was distorted by projecting upward or sideways. Most projectors handle the current correction and vertical models with more features will also handle the horizontal correction.

The "keystone distortion" is a form of video image distortion that occurs with front projectors if the center line of the lens of the projector is not perpendicular to the screen. The trapezoidal distortion results in an image that is shaped like a trapezoid instead of rectangles - the top of the picture is wider than the bottom, or left side is higher than the right, or vice versa. Most front projectors include "keystone correction for distortion" to correct this distortion. Some models have digital vertical keystone correction, while others include digital vertical keystone correction and horizontal. Despite the fact that the correction of the trapezoidal distortion allows greater flexibility of assembly, is a way of processing which usually has a softening effect and a little dimmer in the picture.

Although keystone correction allows greater mounting flexibility, it almost always reduces apparent resolution and makes the image dimmer. Most projector manufacturers today build in an automatic keystone correction to create a uniform image top to bottom. Some projectors have the ability to manually adjust this characteristic while others provide more of a fixed correction solution.

Keystone Correction for Screen Projectors