Techniques are described for performing aspect ratio transformation. Frames of image data from each of one or more input sources are received. A first set of one or more options, including an input aspect ratio, is associated with a first input source. A set of control parameters is determined for each frame from the first input source in accordance with said first input aspect ratio and an output aspect ratio. Each frame from the first input source is processed in accordance with the control parameters for that frame. The processing includes processing a first image from said first input source having said first input aspect ratio to generate a second image having the output aspect ratio. The processing includes converting the first image having the input aspect ratio to the second image having the output aspect ratio if the first input aspect ratio is different from the output aspect ratio.