Systems and methods for obtaining structural information from a digital image

A method for obtaining structural information from a digital image by an electronic device is described. The method includes obtaining a digital image. The method also includes determining a gradient vector for each pixel in a region of interest of the digital image. The method further includes transforming each pixel in the region of interest in accordance with a transform. Transforming each pixel includes determining, for each pixel, a first set of pixels. The first set of pixels includes any pixel along a line that is collinear with or perpendicular to the gradient vector and passes through a pixel location. Transforming each pixel includes incrementing with signed integer values, for each pixel, a first set of values in a transform space corresponding to any of the first set of pixels that are in a first direction of the line.