1. A system to detect a valid hand pose in an image, the system comprising: a processor coupled to memory, the processor to: detect skin pixels in the image using a multi-layer skin filter; classify the skin pixels into a set of foreground skin pixels and a set of background skin pixels; store information about the set of background skin pixels in a persistent memory; determine a set of features from the set of foreground skin pixels; cluster features from the set of features to create a set of hand pose descriptors; determine a set of candidate hand pose region descriptors and a set of candidate hand pose contour descriptors that match the set of hand pose descriptors; and detect the valid hand pose using the set of candidate hand pose region descriptors and the set of candidate hand pose contour descriptors.