An image of a negotiable instrument may be taken by an imaging device and provided from a user to a financial institution. The image may be processed using operations such as deskewing the image, dewarping the image, and detecting corners or edges of the check in the image. Brightness correction may then be performed on the image. The brightness correction may be performed on the image using a histogram of the image with an overlaid reference mark. The negotiable instrument may be deposited in a user's account using the brightness corrected image.