An input device with a power saving system is provided for reducing the power consumption of the input device when the input device is at rest. The input device may include a sensor, a rest mode switch, control logic and a current controller. The sensor may be configured to obtain an image data in response to a light incident on the sensor. The rest mode switch may be configured to set the input device to various levels of rest modes when it is inactive. The control logic may be coupled to the rest mode switch and the sensor. The control logic may be configured to set the input device to process a portion of the image data on the sensor array during a wake up detection operation when the input device is at rest. The current controller may be coupled to the control logic and the sensor and configured to control the current supply limited to a section of the sensor array containing the portion of image data that is being processed by the input device during the wake up detection operation.