1. A system comprising: an image upload assistance module configured to: receive an image from a device of a user; and cause the device of the user to display a sharpness score of the image as a response to the receiving of the image; and a processor configured by an image sharpness detection module to: divide the image into rectangular regions that are equal in quantity along horizontal and vertical axes of the image; calculate blur scores of the rectangular regions that are equal in quantity along the horizontal and vertical axes of the image, the calculating of the blur scores of the rectangular regions being based on a non-reference blur metric; compute a weighting matrix for the image based on two results of filtering the image in perpendicular directions; generate the sharpness score of the image based on application of the weighting matrix to the blur scores of the rectangular regions.