Disclosed are computers and methods of operating those computers. In the methods, a computer in a touch lock state displays a lock screen image showing a cover layer superimposed over, and obscuring, a background layer. A user enters a touch input to a touch screen of the computer, thereby specifying a portion of that touchscreen. The lock screen image is then modified so that the cover layer does not obscure the background layer in the specified portion of the touchscreen. The cover layer in the region of the touchscreen that is not specified in the touch input continues to obscure the background layer in those regions. If the portion of the touchscreen specified by the touch input exceeds a threshold amount the computer may be changed from being in a touch lock state to being in a touch unlock state.