1. A method for automatically selecting similar objects for modification within images stored in a computing device, comprising: receiving, by a processor of a computing device, input via an input device of the computing device specifying a first selection of a first object in an image displayed on a user interface of the computing device; generating, by the processor, a first set of feature descriptors that describe a shape formed by edges of the first object; identifying, by the processor, a plurality of other edges in the remaining portion of the image and generating a second set of feature descriptors describing shapes formed by the other edges; determining, by the processor, one or more edge objects in the image that are similar in shape to the first object by identifying each grouping of the other edges that has feature descriptors of the second set of feature descriptors that describe a shape that is within a similarity threshold to the shape described by the first set of feature descriptors; and modifying, by the processor, pixels in the image of the first object and each similar edge object based on a function specified by a user.