1. A non-transitory machine readable medium storing a program which when executed by at least one processing unit of a computing device provides a graphical user interface (GUI) for editing an image, the GUI comprising: a display area for displaying an image; and an image processing tool for (i) receiving a selection of a location of the image, (ii) overlaying on the image a user interface item comprising a first line located to a first side of the selected location that divides the image into a first area that includes the location and a second area that does not include the location and a second line located to the other side of the location that divides the image into a third area that includes the location and a fourth area that does not include the location, (iii) defining an area of the image to which to apply an effect, the defined area comprising the second and fourth areas that do not include the location, and (iv) applying the effect to the defined area.