Abstract: A phase sensitive optical time domain reflectometry based distributed acoustic sensing system eliminating a degradation in a sensing performance encountered due to a finite extinction ratio of optical elements used to generate optical pulses is provided. A classical Optical Time Domain Reflectometer (OTDR) concept and a phase-OTDR concept are merged to generate an optic pulse for an interrogation with commercially available optic modulators. Characteristics of a light inside a fiber optic cable carry properties of both classical OTDR and phase-OTDR systems. The proposed solution does not require any modifications in a receiver part of the phase-OTDR systems and the proposed solution is used for any type of phase-OTDR system structure.

Abstract: A phase sensitive optical time domain reflectometry based distributed acoustic sensing system eliminating a degradation in a sensing performance encountered due to a finite extinction ratio of optical elements used to generate optical pulses is provided. A classical Optical Time Domain Reflectometer (OTDR) concept and a phase-OTDR concept are merged to generate an optic pulse for an interrogation with commercially available optic modulators. Characteristics of a light inside a fiber optic cable carry properties of both classical OTDR and phase-OTDR systems. The proposed solution does not require any modifications in a receiver part of the phase-OTDR systems and the proposed solution is used for any type of phase-OTDR system structure.

Abstract: Edge information of an input digital image is obtained. Digital image data corresponding to the input digital image is transmitted to a receiver. The edge information is also transmitted to the receiver. An output digital image is obtained at the receiver by processing the digital image data received at the receiver using the edge information received at the receiver. In this way, because the edge information is transmitted separately, as side information, and does not have to be obtained at the receiver, the computational complexity requires of the receiver is low. This enables for example real-time edge-adaptive interpolation to be carried out at the receiver.

Abstract: A method and apparatus for adjusting the contrast of an image, in which each pixel in the image has an initial brightness level that is within a range of brightness levels between a minimum brightness level and a maximum brightness level. For each brightness level within the range, the number of pixels that have the same initial brightness level is counted. The pixels are divided into at least two types by identifying the or each set of pixels having initial brightness levels in which each of a plurality of adjacent ones of said brightness levels has more pixels than a threshold number. The pixels of the plurality of adjacent ones of said brightness levels are treated as a first type. The remaining pixels are treated as a second type. For the or each set of pixels of the first type, contrast enhancement is carried out separately on those pixels.

Abstract: A method and apparatus is disclosed for obtaining interpolation filters for use in a method or apparatus for enhancing the spatial resolution of a digital image. In the method or apparatus for enhancing the spatial resolution, input pixels from a low resolution image are classified and interpolated using the interpolation filters to form a high resolution image. The method for obtaining the interpolation filters includes obtaining a low resolution image from a high resolution source image. A plurality of pixels in the low resolution image are classified with respect to interpolation filters so that each of the plurality of pixels in the low resolution image is allocated to a respective interpolation filter. The interpolation filters are updated. The classifying and updating steps are repeated until a convergence criterion is met.

Abstract: A method and apparatus for adjusting the contrast of an input image is disclosed. Brightness level data of the input image is filtered to obtain at least a low frequency component and a high frequency component. The high frequency component is amplified. The input image and the amplified high frequency component are summed to produce brightness level data of the output image. The filtering is carried out by at least one recursive infinite impulse response filter having a single delay coefficient that is adaptive to areas of high contrast in the input image.

Abstract: Edge information of an input digital image is obtained. Digital image data corresponding to the input digital image is transmitted to a receiver. The edge information is also transmitted to the receiver. An output digital image is obtained at the receiver by processing the digital image data received at the receiver using the edge information received at the receiver. In this way, because the edge information is transmitted separately, as side information, and does not have to be obtained at the receiver, the computational complexity requires of the receiver is low. This enables for example real-time edge-adaptive interpolation to be carried out at the receiver.

Abstract: A method and apparatus for adjusting the contrast of an image, in which each pixel in the image has an initial brightness level that is within a range of brightness levels between a minimum brightness level and a maximum brightness level. For each brightness level within the range, the number of pixels that have the same initial brightness level is counted. The pixels are divided into at least two types by identifying the or each set of pixels having initial brightness levels in which each of a plurality of adjacent ones of said brightness levels has more pixels than a threshold number. The pixels of the plurality of adjacent ones of said brightness levels are treated as a first type. The remaining pixels are treated as a second type. For the or each set of pixels of the first type, contrast enhancement is carried out separately on those pixels.

Abstract: A method and apparatus is disclosed for obtaining interpolation filters for use in a method or apparatus for enhancing the spatial resolution of a digital image. In the method or apparatus for enhancing the spatial resolution, input pixels from a low resolution image are classified and interpolated using the interpolation filters to form a high resolution image. The method for obtaining the interpolation filters includes obtaining a low resolution image from a high resolution source image. A plurality of pixels in the low resolution image are classified with respect to interpolation filters so that each of the plurality of pixels in the low resolution image is allocated to a respective interpolation filter. The interpolation filters are updated. The classifying and updating steps are repeated until a convergence criterion is met.

Abstract: A method and apparatus for adjusting the contrast of an input image is disclosed. Brightness level data of the input image is filtered to obtain at least a low frequency component and a high frequency component. The high frequency component is amplified. The low frequency component and the amplified high frequency component are summed to produce brightness level data of the output image. The filtering is carried out by at least one recursive infinite impulse response filter having a single delay coefficient that is adaptive to areas of high contrast in the input image.