Example of skew:

A skew effect is the rotation of an image such that a horizontal line of text is not perfectly horizontal.

Preventing Skew

Skew may occur if the camera is not level or if the book is not sitting properly in the cradle. Additionally, some materials, such as handwritten records, might be skewed on the page to start with. Generally a properly aligned camera will minimize skew.

Correcting Skew

The process of removing skew from an image is called "deskew." Fortunately, most image editors can correct skew by manually rotating the image. Other software such as ScanTailor and unpaper can automatically remove skew.