1. A vision-based user interface comprising: an image input unit for capturing frame images; an image processor for recognizing a posture in at least one of the captured frame images, and generating a recognized gesture according to the posture; the image processor comprising: a hand area localization unit for limiting range for recognizing the posture to a limited range of the at least one captured frame images; a feature extraction unit for obtaining candidate color blocks within the limited range, fitting the candidate color blocks into rectangular windows, and extracting variant features from each rectangular window; and a model matching unit for transferring the variant features into parallel classifiers to generate a matching calculation result, and determining each rectangular window to be a posture-containing window or a none window, wherein each parallel classifier has a pre-built model corresponding to at least one predefined posture; and a control unit for generating a control command corresponding to the recognized gesture.