1. A low-power object detection hardware, comprising: a hardware scanning window array for storing pixel values or blocks of pixel values based on a two-dimensional sample window of an image, wherein the hardware scanning window array is configured to store pixel values or blocks of pixel values based on different two-dimensional sample windows of the image at different times; computer vision feature computation hardware configured to compute one or more computer vision features based on one or more comparisons of the pixel values or blocks of pixel values stored in the hardware scanning window array, wherein each of the one or more comparisons comprises a comparison between a value for a pixel or a block of pixels and a value for another pixel or block of pixels within the two-dimensional sample window of the image; and a classifier configured to receive the one or more computer vision features computed by the computer vision feature computation hardware and to determine whether a reference object is detected within the two-dimensional sample window of the image.