Some embodiments provide a program that provides a graphical user interface (GUI). The GUI includes a display area for displaying an image that includes several pixels. The GUI includes a selectable masking tool for displaying in the display area an adjustable closed curve to identify a region in the image to apply a color correction operation. The selectable masking tool includes a selectable control for modifying the adjustable closed curve through a range of elliptical shapes that ranges from a pure ellipse to an approximate rectangle. The GUI includes a selectable GUI item for applying the color correction operation based on the selectable masking tool.