Abstract: An image processing apparatus capable of performing good luminance correction without performing a cumbersome process is provided. The image processing apparatus includes an illumination light component estimation unit which calculates an estimated illumination light component of an original image, an estimated illumination light component correction unit which outputs a corrected estimated illumination light component obtained by correcting the estimated illumination light component, and a Retinex processing unit which corrects a luminance component of the original image by dividing the luminance component by the corrected estimated illumination light component.

Abstract: An image processing apparatus capable of performing good luminance correction without performing a cumbersome process is provided. The image processing apparatus includes an illumination light component estimation unit which calculates an estimated illumination light component of an original image, an estimated illumination light component correction unit which outputs a corrected estimated illumination light component obtained by correcting the estimated illumination light component, and a Retinex processing unit which corrects a luminance component of the original image by dividing the luminance component by the corrected estimated illumination light component.

Abstract: An optical wireless communications system has a first optical wireless communications apparatus for transmitting a pilot beam and a second optical wireless communications apparatus for receiving the pilot beam to have a match for an optical axis of the first optical wireless communications apparatus and another optical axis of the second optical wireless communications apparatus. The first optical wireless communications apparatus has a modulator for modulating the pilot beam with a specific signal. The second optical wireless communications apparatus has a demodulator for demodulating the modulated and transmitted pilot beam to reproduce the specific signal and sending the reproduced specific signal to at least either the second optical wireless communications apparatus or an apparatus connected to the second optical wireless communications apparatus.

Abstract: An optical-axis directional indicating apparatus for optical communication includes a photoreceptor having a light-receiving surface and a plurality of optical receiving elements arranged on the surface in a first direction and a second direction orthogonal to the first direction, to receive a transmitted light beam, a detector to detect levels of the light beam received at the optical receiving elements, a plurality of display elements arranged in the first and second directions so as to correspond to the optical receiving elements of the photoreceptor, and a switch circuit to selectively turn on or off the display elements in accordance with the levels of the light beam detected by the detector, to indicate whether or not an optical axis of the light beam is deviated in the first and/or the second direction on the light-receiving surface of the photoreceptor.

Abstract: An optical wireless communications system has a first optical wireless communications apparatus for transmitting a pilot beam and a second optical wireless communications apparatus for receiving the pilot beam to have a match for an optical axis of the first optical wireless communications apparatus and another optical axis of the second optical wireless communications apparatus. The first optical wireless communications apparatus has a modulator for modulating the pilot beam with a specific signal. The second optical wireless communications apparatus has a demodulator for demodulating the modulated and transmitted pilot beam to reproduce the specific signal and sending the reproduced specific signal to at least either the second optical wireless communications apparatus or an apparatus connected to the second optical wireless communications apparatus.

Abstract: An optical-axis directional indicating apparatus for optical communication includes a photoreceptor having a light-receiving surface and a plurality of optical receiving elements arranged on the surface in a first direction and a second direction orthogonal to the first direction, to receive a transmitted light beam, a detector to detect levels of the light beam received at the optical receiving elements, a plurality of display elements arranged in the first and second directions so as to correspond to the optical receiving elements of the photoreceptor, and a switch circuit to selectively turn on or off the display elements in accordance with the levels of the light beam detected by the detector, to indicate whether or not an optical axis of the light beam is deviated in the first and/or the second direction on the light-receiving surface of the photoreceptor.

Abstract: A transmitter transmits an optical signal to a receiver for optical wireless communications. The receiver returns to the transmitter a pilot light representing light-receiving level information of the received optical signal. The transmitter has a set of 2×2 light-receiving elements for receiving the pilot light returned from the receiver, and executes a rough optical axis adjustment based on the difference among the light-receiving levels detected by respective light-receiving elements. Then, the transmitter executes a fine optical axis adjustment based on the light-receiving level information contained in the pilot light.