An in-vivo device, system, and method are described where an in-vivo device may transmit an image stream to an external receiving device. Reducing the size of the image data necessary for transmission may conserve energy consumed by the in-vivo device during transmission. An image data comparator unit incorporated within the in-vivo device may compare a captured image to a previously transmitted image and transmit, for example, only captured images that are substantially dissimilar to a previously captured image.