1. A processor-implemented method for enhancing image differences in an input difference image comprising the steps of: selecting at least one target pixel in the difference image, wherein a value associated with the selected target pixel exceeds a threshold value; setting a paintbrush operation as opaque or non-opaque; and generating an enhanced difference image by updating an existing value associated with at least one neighboring pixel in an area around the target pixel by: setting the value associated with the at least one neighboring pixel to the value associated with the selected target pixel, if the paintbrush operation is opaque, and obtaining the value of the at least one neighboring pixel by performing a blending operation using the value associated with the selected target pixel and the existing value associated with the neighboring pixel, if the paintbrush operation is non-opaque.