Abstract: A wavelength swept light source includes a sawtooth waveform as a main waveform and an exponential component of the sawtooth waveform to the controlled voltage of the electro-optic deflector. The controlled voltage is controlled so that, as an oscillation wavelength to be swept is swept towards a longer wavelength side, a change rate of the oscillation wavelength is increased.

Abstract: An image retrieval method comprising: a step of extracting at least one query feature vector from a query image on which a subject of the image retrieval is captured, the query feature vector representing a local feature of the query image; a step of accessing an image data base in which a plurality of reference images are stored previously, each reference image being stored in conjunction with learning images generated therefrom and reference feature vectors representing local features of the reference image and the learning images; a comparing step of comparing the query feature vector with the reference feature vectors stored in conjunction with each reference image using an approximate nearest neighbor search to find a reference feature vector approximately nearest to the query feature vector; and a selecting step of selecting a reference image with which the found reference feature vector is stored in conjunction from the reference images as a retrieval result wherein: the learning image is generated by

Abstract: In a wavelength swept light source using a polygon mirror in a well-known art, an oscillation wavelength roughly linearly varies in an upwardly slight convex shape with respect to time. On the other hand, in a wavelength swept light source of SS-OCT, the wavelength is required to vary so that a wavenumber (inverse of wavelength) linearly varies on a time axis. The wavelength swept light source of the well-known art has had a drawback that such wavelength variation cannot be implemented; non-linear distortion occurs in a resultant OCT image; and thereby, a point spread function cannot be kept sharp.

Abstract: Provided is a method for constructing an image database for object recognition, which includes a feature extraction step of extracting local descriptors from object images which are to be stored in an image database, a scalar quantization step of quantizing a numeric value indicating each dimension of each of the local descriptors into a predetermined number of bit digits, and a storing step of organizing each of the local descriptors after the quantization to be able to be searched for in the closest vicinity, giving to the local descriptor an identifier of the image from which the local descriptor has been extracted, and storing the local descriptor to which the identifiers are given in the image database.

Abstract: For object recognition based on nearest neighbor search of local descriptors such as SIFT, it is important to keep the nearest neighbor search efficient to deal with a huge number of descriptors. The present invention provides methods of efficient recognition. In one embodiment, the method is based on the observation that the level of accuracy of nearest neighbor search for correct recognition depends on images to be recognized. The method is characterized by the mechanism that multiple recognizers with approximate nearest neighbor search are cascaded in the order of the level of approximation so as to improve the efficiency by adaptively controlling the level to be applied depending on images. In another embodiment the method is characterized by excluding local descriptors with low discriminability when a plenty of local descriptors are present in the vicinity and a plenty of distance calculation are required.

Abstract: An image retrieval method comprising: a step of extracting at least one query feature vector from a query image on which a subject of the image retrieval is captured, the query feature vector representing a local feature of the query image; a step of accessing an image data base in which a plurality of reference images are stored previously, each reference image being stored in conjunction with learning images generated therefrom and reference feature vectors representing local features of the reference image and the learning images; a comparing step of comparing the query feature vector with the reference feature vectors stored in conjunction with each reference image using an approximate nearest neighbor search to find a reference feature vector approximately nearest to the query feature vector; and a selecting step of selecting a reference image with which the found reference feature vector is stored in conjunction from the reference images as a retrieval result wherein: the learning image is generated by

Abstract: Provided is a method for constructing an image database for object recognition, which includes a feature extraction step of extracting local descriptors from object images which are to be stored in an image database, a scalar quantization step of quantizing a numeric value indicating each dimension of each of the local descriptors into a predetermined number of bit digits, and a storing step of organizing each of the local descriptors after the quantization to be able to be searched for in the closest vicinity, giving to the local descriptor an identifier of the image from which the local descriptor has been extracted, and storing the local descriptor to which the identifiers are given in the image database.

Abstract: The invention provides a method for actualizing a high-speed object recognition process in an object recognition which extracts feature vectors from an input image where an object is captured, the feature vectors representing the object with the large number of the feature vectors; and retrieves, among an image database, one or more images whose features are matched. The invention also provides a method for saving a memory capacity required for the image database. Suggested are methods each of the methods being capable of reducing a processing time required to perform a task which recognizes the object described by a plurality of the feature vectors with use of an approximate nearest neighbor search technique. One of the suggested methods is actualized by excluding such feature vectors that a large number of feature vectors are present in the vicinity and a large number of distance calculations, therefore, are required.

Abstract: An optical communication system is constructed which enables highly reliable and flexible connection to communication nodes connected to a path establishment circuit, by utilizing wavelength-routing characteristics of a path establishment circuit such as an arrayed waveguide grating. The optical communication system has multiple communication nodes having a signal output port and signal input port pair, and a path establishment circuit having multiple optical input ports and multiple optical output ports which are set so that optical signals input from the respective optical input ports are output to predetermined optical output ports corresponding to the wavelengths of the optical signals.

Abstract: An optical communication network system and a wavelength-routing device and a communication node therefor are provided which can easily increase the optical paths between communication nodes, which are capable of expanding transmission capacity, and which excel in flexibility and expandability. An optical signal within a wavelength band (?Bm±??m) which has been transmitted from a predetermined communication node (200-1 through 200-4) is subjected to wavelength-band demultiplexing of the wavelength bands by wavelength-band demultiplexers (220-1 through 220-4) of a wavelength-routing device (210), and is then subjected to wavelength-routing by arrayed-waveguide gratings (241 through 244) according to the wavelength bands, and furthermore is multiplexed with optical signals of other wavelength bands by wavelength-band multiplexers (230-1 through 230-4), and after having been outputted, is transmitted to a communication node.

Abstract: A fiber optic communication system includes a device of switching and setting wavelength of optical signals used in communication by network-node equipments, which sets the mapping of the wavelength of the optical signal used in communication by the network node equipments, and the input/output ports of an array waveguide grating (AWG), so as to construct a predetermined logical network topology by a plurality of network node equipments which are connected via optical fibers to the array waveguide grating that outputs optical signals inputted to optical input ports, to predetermined optical output ports in accordance with the wavelength thereof. As well as enabling a simple construction, it is easy to realize flexible network design, construction, and operation, and different network groups can also be easily connected to each other. Moreover, a fiber optic communication system having robust security and which can be stably operated even at the time of failure is realized at low cost.

Abstract: An optical communication equipment comprises shared optical sources 88a–88d to be shared by communication nodes 100a–100d, the wavelengths of optical signals 76a–76d are converted into desired wavelengths ?a–?d according to the addressed information of the corresponding optical label signals 77a–77d by using the shared optical sources 88a–88d, and routed to the addressed communication nodes without being converted into electrical signals by using the wavelength routing function of the cyclic-wavelength arrayed-waveguide grating (AWG) 120. The load of each communication node can be reduced by incorporating the multi-wavelength optical sources, which can be shared among individual communication nodes, into the router 80.

Abstract: An optical communication equipment comprises shared optical sources 88a–88d to be shared by communication nodes 100a–100d, the wavelengths of optical signals 76a–76d are converted into desired wavelengths ?a–?d according to the addressed information of the corresponding optical label signals 77a–77d by using the shared optical sources 88a–88d, and routed to the addressed communication nodes without being converted into electrical signals by using the wavelength routing function of the cyclic-wavelength arrayed-waveguide grating (AWG) 120. The load of each communication node can be reduced by incorporating the multi-wavelength optical sources, which can be shared among individual communication nodes, into the router 80.

Abstract: A fiber optic communication system includes a device of switching and setting wavelength of optical signals used in communication by network-node equipments, which sets the mapping of the wavelength of the optical signal used in communication by the network node equipments, and the input/output ports of an array waveguide grating (AWG), so as to construct a predetermined logical network topology by a plurality of network node equipments which are connected via optical fibers to the array waveguide grating that outputs optical signals inputted to optical input ports, to predetermined optical output ports in accordance with the wavelength thereof. As well as enabling a simple construction, it is easy to realize flexible network design, construction, and operation, and different network groups can also be easily connected to each other. Moreover, a fiber optic communication system having robust security and which can be stably operated even at the time of failure is realized at low cost.

Abstract: An optical communication network system and a wavelength-routing device and a communication node therefor are provided which can easily increase the optical paths between communication nodes, which are capable of expanding transmission capacity, and which excel in flexibility and expandability. An optical signal within a wavelength band (?Bm±??m) which has been transmitted from a predetermined communication node (200-1 through 200-4) is subjected to wavelength-band demultiplexing of the wavelength bands by wavelength-band demultiplexers (220-1 through 220-4) of a wavelength-routing device (210), and is then subjected to wavelength-routing by arrayed-waveguide gratings (241 through 244) according to the wavelength bands, and furthermore is multiplexed with optical signals of other wavelength bands by wavelength-band multiplexers (230-1 through 230-4), and after having been outputted, is transmitted to a communication node.

Abstract: A light-controlled light modulator can achieve high-speed, low-loss wavelength conversion. Continuous light with a wavelength ?j is launched into an MMI coupler via a port, and is split into two parts by the MMI coupler, which are led to a loop-type interferometer. In the loop-type interferometer, the two parts travel separately around the loop as clockwise traveling light and counterclockwise traveling light, are combined by the MMI coupler again via a filter-equipped phase modulator, thereby being emitted to the port. In this state, signal light ?i(s) with a wavelength ?i is launched into the filter-equipped phase modulator via a port. Even when the wavelength ?i of the signal light ?i(s) is equal to the wavelength ?j of the wavelength converted output light, the wavelength conversion can be achieved with preventing noise from being mixed into the output light emitted from a port.

Abstract: A light-controlled light modulator can achieve high-speed, low-loss wavelength conversion. Continuous light with a wavelength &lgr;j is launched into an MMI coupler via a port, and is split into two parts by the MMI coupler, which are led to a loop-type interferometer. In the loop-type interferometer, the two parts travel separately around the loop as clockwise traveling light and counterclockwise traveling light, are combined by the MMI coupler again via a filter-equipped phase modulator, thereby being emitted to the port. In this state, signal light &lgr;i(s) with a wavelength &lgr;i is launched into the filter-equipped phase modulator via a port. Even when the wavelength &lgr;i of the signal light &lgr;i(s) is equal to the wavelength &lgr;j of the wavelength converted output light, the wavelength conversion can be achieved with preventing noise from being mixed into the output light emitted from a port.

Abstract: An optical communication equipment comprises shared optical sources 88a-88d to be shared by communication nodes 100a-100d, the wavelengths of optical signals 76a-76d are converted into desired wavelengths &lgr;a-&lgr;d according to the addressed information of the corresponding optical label signals 77a-77d by using the shared optical sources 88a-88d and routed to the addressed communication nodes without being converted into electrical signals by using the wavelength routing function of the cyclic-wavelength arrayed-waveguide grating (AWG) 120. The load of each communication node can be reduced by incorporating the multi-wavelength optical sources, which can be shared among individual communication nodes, into the router 80.

Abstract: An optical communication system is constructed which enables highly reliable and flexible connection to communication nodes connected to a path establishment circuit, by utilizing wavelength-routing characteristics of a path establishment circuit such as an arrayed waveguide grating. The optical communication system has multiple communication nodes having a signal output port and signal input port pair, and a path establishment circuit having multiple optical input ports and multiple optical output ports which are set so that optical signals input from the respective optical input ports are output to predetermined optical output ports corresponding to the wavelengths of the optical signals.

Abstract: An optical communication equipment comprises shared optical sources 88a-88d to be shared by communication nodes 100a-100d, the wavelengths of optical signals 76a-76d are converted into desired wavelengths &lgr;a-&lgr;d according to the addressed information of the corresponding optical label signals 77a-77d by using the shared optical sources 88a-88d, and routed to the addressed communication nodes without being converted into electrical signals by using the wavelength routing function of the cyclic-wavelength arrayed-waveguide grating (AWG) 120. The load of each communication node can be reduced by incorporating the multi-wavelength optical sources, which can be shared among individual communication nodes, into the router 80.