An image sensor comprised of an array of photo elements (pixels) includes a device for randomly addressing individual pixels and a device for selectively varying the number of pixels which can be read out on any one reading cycle. The random addressing of pixels enables the readout of pixels located in selected regions of interest. Limiting the readout of the images to areas of interest allows an increase in the frame rate of the images. Relatively large groups of pixels can be read out simultaneously and the resulting signals can be merged into superpixel signals to provide high speed data capture, albeit at relatively lower resolution, since there will be a reduced number of data samples in each image. This feature is useful to rapidly scan and analyze a scene being viewed in order to locate an area of interest. Once an area of interest is located, the number of pixels read out on each cycle may be reduced to provide a higher resolution, lower speed, readout of the area of interest.