1. A method for testing a digital camera module, comprising: scaling a digital image captured by the digital camera module to a smaller size; horizontal direction filtering the scaled image by applying, row by row, a horizontally oriented one-dimensional spatial filter to each pixel of the scaled image; vertical direction filtering the scaled image by applying, column by column, a vertically oriented one-dimensional spatial filter to each pixel of the scaled image; combining the horizontal direction filtered image and the vertical direction filtered image, wherein edge regions and corner regions of the combined filtered image are created differently than its middle region; thresholding the combined filtered image; and marking a selected plurality of pixels of the thresholded image as a blemish region.