Photographers usually take pictures from a few meters distance. The reason is that in close up images, faces tend to look distorted and unnatural. Face Undistortion corrects this by simulating the effect of a photo taken from a distance, showing an image of you which is closer to reality.
The amount of undistortion may be controlled by the slider that appears when this feature is enabled. Just choose a value that you think looks good. The effect is best seen if your face is relatively close to the camera. Pay attention to the size of your nose!
To further improve the results click the 'Adapt face mask' button.
A window opens, which allows you to adjust the width and height of the face mask. Make sure it matches the size of your face. CatchEye will remember your settings.