An interface (402) to a video imaging device (490) that generates captured frames of a video image (100) is described. The interface includes control registers (430) that store at least two sets of stream parameters (401) corresponding to at least two regions of interest (ROIs) and a function (410) that generates at least two corresponding ROI video streams (460) that are derived from the captured frames as essentially simultaneous output signals using the at least two sets of stream parameters. In some embodiments a new selection value (436) is determined from a current selection value and a derivative parameter stored as a portion of a set of stream parameters. In these embodiments, the generating of the at least two corresponding ROI video streams as essentially simultaneous output signals includes using the new selection value.