The present disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for providing virtual keyboards. In one aspect, a system includes a camera, a display, a video feature extraction module and a gesture pattern matching module. The camera captures a sequence of images containing a finger of a user, and the display displays each image combined with a virtual keyboard having a plurality of virtual keys. The video feature extraction module detects motion of the finger in the sequence of images relative to virtual sensors of the virtual keys, and determines sensor actuation data based on the detected motion relative to the virtual sensors. The gesture pattern matching module uses the sensor actuation data to recognize a gesture.