A digital image captured by a digital camera module is scaled to a smaller size, and separately horizontal direction filtered and vertical direction filtered using one-dimensional spatial filters. The horizontal direction filtered image and the vertical direction filtered image are combined, wherein edge regions and corner regions of the combined filtered image are created differently than its middle region. The combined filtered image is then thresholded selected pixels of the thresholded image are marked as a blemish region. Other embodiments are also described and claimed.