1. A machine implemented method, the method comprising: identifying an approximate location of a feature in a preliminary image that was captured by an image sensor; computing, using processing circuitry coupled to the image sensor, a gradient phase map of image pixel intensities within the approximate location, wherein the gradient phase map assigns each pixel a gradient phase angle which is the direction of the gradient at the pixel, and wherein the direction of the gradient shows the direction of the largest pixel intensity change with respect to surrounding pixels; determining a projection result by applying a projection function to the gradient phase map, wherein the projection function includes an integral projection function, comprising: a vertical integral projection function (“IPF v ”) including a mean of each pixel's gradient phase angle in the approximate location, for each column of the approximate location in a vertical direction; and a horizontal integral projection function (“IPF h ”) including a mean of each pixel's gradient phase angle in the approximate location, for each row of the approximate location in a horizontal direction; and analyzing the projection result to determine a state of the feature.