In one example, an apparatus comprises: an image sensor comprising an array of pixel cells, each pixel cell including a photodiode and circuits to generate image data, the photodiodes formed in a first semiconductor substrate; and a controller formed in one or more second semiconductor substrates that include the circuits of the array of pixel cells, the first and second semiconductor substrates forming a stack and housed within a semiconductor package. The controller is configured to: determine whether first image data generated by the image sensor contain features of an object; based on whether the first image data contain the features of the object, generate programming signals for the image sensor; and control, based on the programming signals, the image sensor to generate second image data.