1. A method for automatically selecting similar objects for modification within images stored in a computing device, comprising: receiving, by a processor of the 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 a remaining portion of the image excluding the first object 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; updating the user interface to include visual selection indicators applied to the first object and each similar edge object; 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, wherein said modifying based on the function is separate from updating the user interface to include visual selection indicators.