Commanding a computer or electronic device via a touch screen or touchpad by using more than one finger. For example, Apple's Multi-Touch technology in the iPhone and iPod touch lets the user zoom in on a photo by placing thumb and forefinger over the image and sliding them apart. Sliding the fingers back together in a pinching motion makes the image smaller.|
A multitouch display may also be pressure sensitive, as well as sensitive to gestures, which are predefined motions that are commands to perform an action such as rotate the object on the z-axis.
Sensing Deflected Light
Microsoft's Surface computer uses multitouch in a table top display that can be used by more than one person at a time. Perceptive Pixel's technology (www.perceptivepixel.com) makes wall-mounted multitouch displays such as CNN's "Magic Wall" election map that enables journalists to track candidates state by state.
Both the Surface computer and Perceptive Pixel systems project images onto acrylic screens along with near-infrared or infrared light from one or more LED light sources. When fingers touch the screen, the light is deflected, and sensors pick up the changes. See touch scroll, touch screen, Magic Mouse and gesture recognition.
Microsoft's Surface computer uses multitouch to let people manipulate objects more like the real world. In this light table example, photos are moved around as if they were printed on paper, but can also be resized. (Image courtesy of Microsoft Corporation.)