A method for quantifying a feature represented by image data, comprising: receiving image data; determining an operator for quantifying a feature of an image described by image data, wherein the operator includes a plurality of blocks, wherein the blocks include a primary block, encompassing a primary location, and outer blocks, wherein the outer blocks surround the primary block, wherein each of the outer blocks is sized to cover three, five, or more than five pixels of the image, and wherein the blocks are arranged such that an external pixel lies between the primary block and at least one of the outer blocks, or a common internal pixel lies within two of the blocks; determining a gradient direction, about the primary location, of intensity of the image data near the primary location, wherein the primary location corresponds to the center of the primary block; rotating the operator about the primary location based on the gradient direction, wherein the rotated operator includes a rotated primary block and repositioned outer blocks, wherein rotating the operator includes determining locations of the repositioned outer blocks surrounding the primary block, wherein the rotated primary block is rotated about the primary location and the repositioned outer blocks are rotated about the primary location; determining a value indicative of an average intensity of the rotated primary block and each of the repositioned outer blocks of the rotated operator; comparing the value indicative of the average intensity of the rotated primary block to each of the values indicative of the average intensities of the repositioned outer blocks and representing each comparison with a binary value; and quantifying a feature represented by the image data by generating a characteristic number based on the binary values resulting from comparing the value indicative of the average intensity of the rotated primary block to the values indicative of the average intensities of the repositioned outer blocks. receiving image data; determining an operator for quantifying a feature of an image described by image data, wherein the operator includes a plurality of blocks, wherein the blocks include a primary block, encompassing a primary location, and outer blocks, wherein the outer blocks surround the primary block, wherein each of the outer blocks is sized to cover three, five, or more than five pixels of the image, and wherein the blocks are arranged such that an external pixel lies between the primary block and at least one of the outer blocks, or a common internal pixel lies within two of the blocks; wherein the blocks include a primary block, encompassing a primary location, and outer blocks, wherein the outer blocks surround the primary block, wherein each of the outer blocks is sized to cover three, five, or more than five pixels of the image, and wherein the blocks are arranged such that an external pixel lies between the primary block and at least one of the outer blocks, or a common internal pixel lies within two of the blocks; determining a gradient direction, about the primary location, of intensity of the image data near the primary location, wherein the primary location corresponds to the center of the primary block; rotating the operator about the primary location based on the gradient direction, wherein the rotated operator includes a rotated primary block and repositioned outer blocks, wherein rotating the operator includes determining locations of the repositioned outer blocks surrounding the primary block, wherein the rotated primary block is rotated about the primary location and the repositioned outer blocks are rotated about the primary location; determining a value indicative of an average intensity of the rotated primary block and each of the repositioned outer blocks of the rotated operator; comparing the value indicative of the average intensity of the rotated primary block to each of the values indicative of the average intensities of the repositioned outer blocks and representing each comparison with a binary value; and quantifying a feature represented by the image data by generating a characteristic number based on the binary values resulting from comparing the value indicative of the average intensity of the rotated primary block to the values indicative of the average intensities of the repositioned outer blocks.