1. A system comprising: a processor and executable instructions accessible on a non-transitory computer-readable medium that, when executed, cause the processor to perform operations comprising: receiving an image from a device of a user; causing the device of the user to display a sharpness score of the image as a response to the receiving of the image; dividing the image into rectangular regions that are equal in quantity along horizontal and vertical axes of the image; calculating 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; computing a weighting matrix for the image based on two results of filtering the image in perpendicular directions; generating the sharpness score of the image based on application of the weighting matrix to the blur scores of the rectangular regions; when the sharpness score of the image is below a certain pre-established threshold, identifying one or more stock images corresponding to an item represented in the image; and displaying the identified one or more stock images on the device of the user as a selectable substitute for the image.