Apparatus and method for determining a confidence value of a disparity estimate

A method for determining a confidence value of a disparity estimate for a pixel or a group of pixels of a selected image of at least two stereo images, wherein the confidence value is a measure for an improved reliability value of the disparity estimate for the pixel or the group of pixels, the method comprising:

• determining an initial reliability value of the disparity estimate for the pixel or the group of pixels, wherein the initial reliability value is one of at least reliable and unreliable;
• determining a first distance of the pixel or the group of pixels to a nearest pixel or group of pixels with an unreliable disparity estimate;
• determining a second distance of the pixel or the group of pixels to a nearest pixel or group of pixels with a not-reliable disparity estimate, wherein the not-reliable disparity estimate is either undecided or unreliable;
• determining the confidence value of the disparity estimate for the pixel or the group of pixels from the determined first distance and the determined second distance;
• determining a special consistency value from the determined first distance, an upper bound for the first distance, the determined second distance, and a range factor;
• and
• classifying the disparity estimate of the pixel or the group of pixels as undecided if the disparity estimate of the pixel or the group of pixels is neither reliable nor unreliable.