For matching accuracy the correspondence should be the following:Highest = 0High = 1Medium = 2Low = 4Lowest = 8For depth maps quality:Ultra = 1High = 2Medium = 4Low = 8Lowest = 16Basically, the value defines the downscaling factor by each side applied to original image. The only exception is Highest matching accuracy, where the images are upscaled by two times by each side.