How does keystone correction work?

Adjust the projection size until the image fits the screen as best as possible. Projectors with a zoom function usually have a dial on the top. By turning this, you can make the projection larger or smaller. If the projector doesn't have a zoom function, you have to move the device forwards or backwards.

With most projectors, you'll find the keystone correction on top of the device. In some cases, these buttons can also be found on the remote. You can recognize the buttons by the trapezoidal icon. You'll see small arrows on the narrowest side of the icon. These arrows indicate which corners you adjust when you press the button.

Press the buttons to apply the horizontal and/or vertical keystone correction. Continue until the corners of the image fit exactly into the corners of the screen. Is this not possible in one go and do you want to start over? Usually, the projector shows a menu on which you can see all the adjustments made. This way, you can easily reset the corners to the basic settings.