Region Extraction by Averaging and Thresholding

Regions in a picture that differ texturally from their surroundings can often be extracted by 1) applying a local operation to every point of the picture, 2) averaging the results, and 3) thresholding. This approach will usually not work if there are too many differently textured regions present, since the average for one type of region may then be indistinguishable from the average resulting from a mixture of two other types that adjoin. The amount of averaging that should be used depends on the coarseness of the texture. An approach to choosing this amount automatically was investigated, but the results were not as good as those obtained with a fixed high degree of averaging.