Historically, acutance was enhanced chemically during development of a negative (High Acutance Developers), or by optical means in printing (Unsharp Masking). In digital photography, onboard camera software and image postprocessing tools such as Photoshop or the GIMP offer various sharpening facilities, the most widely used of which is known as "unsharp mask" because the algorithm is derived from the eponymous analog processing method.