A mechanism for enabling a user to vary the scale or zoom of image data for aspect ratio conversion using a graphical user interface is disclosed. A user may move a selector of the graphical user interface to one end for selecting a linear scaling, to the other end for selecting a parabolic scaling or in between for selecting a scaling associated with another function, thereby enabling a user to vary the magnitude of the scaling across the image data. A parametric function with a single parameter may be used to scale the image data, where the movement of the selector may change the parameter and consequently vary the scaling of the image data. In this manner, a user may efficiently vary or select the scaling of the image data using a graphical user interface to reduce objectionable distortion associated with changing the aspect ratio of the image data.