Knifing

Knifing - method of removing marks and other blemishes from the surface of a print by gentle scraping with the tip of a sharp knife.

b) Cut out unwanted objects after the picture is taken by spotting with dye, knifing or bleaching.
Visual appeal and impact
a) Something that catches the eye or holds the attention can transcend the artistic merit of a picture.

See also: Composition, Depth of field, Bleaching, Shape, Bleach