1. A computer-implemented range image generation method comprising: receiving, by a computer processor, data representing an input image and a reference image; computing, by the computer processor, a raw disparity-space correlation disparity result representing a non-optimized disparity between a first pixel in a reference image and a second pixel in the input image; computing, by the computer processor, an optimized disparity-space correlation disparity result representing a disparity between a third pixel in the reference image and a fourth pixel in the input image, the first and third pixels being different pixels; computing, by the computer processor, a raw sub-pixel disparity estimate for the first pixel and an optimized sub-pixel disparity estimate for the third pixel using the raw disparity-space correlation disparity result and the optimized disparity-space correlation disparity result, respectively; and generating, by the computer processor, a range image, wherein, with respect to the first pixel, the range image is based on the raw sub-pixel disparity estimate and is not based on the optimized sub-pixel disparity estimate, wherein, with respect to the third pixel, the range image is based on the optimized sub-pixel disparity estimate and is not based on the raw sub-pixel disparity estimate, and wherein the raw disparity-space correlation disparity result and the optimized disparity-space correlation disparity result are each weighted in proportion to a ratio between the raw sub-pixel correlation disparity result and the optimized sub-pixel correlation disparity result.