Abstract: A method for estimating the white Gaussian noise level that corrupts a digital image by discriminating homogeneous blocks from blocks containing a textured area and skipping these last blocks when evaluating the noise standard deviation.

Abstract: A method is for filtering data output from an array of pixels in an image sensor. The method may include filtering noise from variation in pixel response across the array. An electronic device may have a device for filtering data output from an array of pixels in an image sensor. The device may include a noise filter for removing variation in pixel response across the array.

Abstract: A method for estimating the white Gaussian noise level that corrupts a digital image by discriminating homogeneous blocks from blocks containing a textured area and skipping these last blocks when evaluating the noise standard deviation.

Abstract: A method is for filtering data output from an array of pixels in an image sensor. The method may include filtering noise from variation in pixel response across the array. An electronic device may have a device for filtering data output from an array of pixels in an image sensor. The device may include a noise filter for removing variation in pixel response across the array.

Abstract: A method for processing a video data stream including a series of pixel values corresponding to pixel sites in an electronic imaging device includes the step of filtering the video data stream in real time to correct or modify defective pixel values based on a plurality of neighboring pixel values. The filtering of each pixel value uses a current pixel value as part of a data set including the neighboring pixel values in determining whether and/or how to correct or modify the current pixel value. The pixel values which are most severely defective are identified and stored. A first filtering algorithm is applied to those pixels whose locations are not stored, and a second filtering algorithm is applied to the most severely defective pixels whose locations have been stored. The filtering algorithm includes sorting the current pixel value and the neighboring pixel values into a rank order and modifying the current pixel value on the basis of its place in the rank order.

Abstract: Lighting flicker in the output of a video imaging device is detected. The video imaging device has a main picture area divided into pixels for producing successive images at a frame rate. A series of signals are produced from at least one additional picture area adjacent the main picture area, with the additional picture area having a size substantially larger than a pixel. Each of the signals is a function of light incident on the additional picture area in a time period substantially shorter than that of the frame rate. A predetermined number of the signals are accumulated to form a series of compound samples, and the compound samples are filtered to detect components indicating the lighting flicker. The filtering is performed using a bandpass filter tuned to the nominal flicker frequency. The compound samples are formed at a sample rate which is a multiple of the nominal flicker frequency, and the filtering is performed by taking the fundamental output component of a radix-N butterfly.

Abstract: Solid state image sensors, and methods of operation thereof, includes an array of photosensitive pixels arranged in rows and columns and in which pixel data signals are read out from the pixels via column circuits, which introduces column fixed pattern noise to the signals. The signals are selectively inverted at the inputs to the column circuits and the inversion is reversed following output from the column circuits. Each column circuit may include an analog-to-digital converter and a digital inverter for inverting digital output therefrom. The selective inversion may be applied to alternate rows or groups of rows of the pixel data, and may be applied differently to different frames of the pixel data. These techniques result in column fixed pattern noise being modulated in a manner which makes the noise less apparent to the eye, and which facilitates subsequent cancellation of the noise.

Abstract: A video signal is produced from a color imaging array of the type having luminance elements of a first color (typically green) and chrominance elements of second and third colors (typically red and blue). The video signal processing includes, for each element of the second color, estimating a chrominance value of the third color as a function of the actual chrominance value of that element, the local neighborhood of actual chrominance values of the third color, and an anti-aliasing control value derived from the local neighborhood of actual luminance values and actual third color chrominance values. In preferred forms, a similar estimation of the second color at each third color element is performed.

Abstract: A signal processing method for estimating luminance is provided, for use with matrix patterned image sensors where elected sensor pixels (G), preferably green pixels, from which luminance-representative signals are taken, only occupy alternate horizontal and vertical positions in the matrix pattern. The method is designed for detecting luminance contour edges and/or stripes in an image so as to enable images obtained form the sensor to be enhanced. Each pixel site (Hc) which is at the centre of both a row and a column of five pixels, and which is not the site of an elected (green) pixel, is identified and, for each such identified site (Hc), the signals output from the immediately adjacent four pixels (Gn,Ge,Gs,Gw) in said row and column are processed to establish both signal amplitude and pixel position.

Abstract: An integrated circuit suitable for use as a multi-spectral image array sensor (1) comprises an array of pixels (2) for sensing radiation of different wavelengths e.g. different colours. The array has at least one row of cells containing a plurality of series (R,G) of pixels which series are interspersed with each other. Each series consists essentially of pixels (2) for sensing radiation of substantially the same wavelength e.g. the same colour. At least two horizontal shift registers (16,18) are provided, each register being coupled to pixels (2) of a respective one of the plurality of series (R,G) of pixels so as to enable the outputs from the pixels of each series to be read out consecutively at an array output (11). In a preferred embodiment the pixels (2) are preferably arranged in a Bayer matrix of Red, Green and Blue pixels and two interleaved shift registers (16,18) are provided for reading out the pixel outputs for each colour consecutively, in each row.

Abstract: Lighting flicker in the output of a video imaging device is detected. The video imaging device has a main picture area divided into pixels for producing successive images at a frame rate. A series of signals are produced from at least one additional picture area adjacent the main picture area, with the additional picture area having a size substantially larger than a pixel. Each of the signals is a function of light incident on the additional picture area in a time period substantially shorter than that of the frame rate. A predetermined number of the signals are accumulated to form a series of compound samples, and the compound samples are filtered to detect components indicating the lighting flicker. The filtering is performed using a bandpass filter tuned to the nominal flicker frequency. The compound samples are formed at a sample rate which is a multiple of the nominal flicker frequency, and the filtering is performed by taking the fundamental output component of a radix-N butterfly.

Abstract: Solid state image sensors, and methods of operation thereof, includes an array of photosensitive pixels arranged in rows and columns and in which pixel data signals are read out from the pixels via column circuits, which introduces column fixed pattern noise to the signals. The signals are selectively inverted at the inputs to the column circuits and the inversion is reversed following output from the column circuits. Each column circuit may include an analog-to-digital converter and a digital inverter for inverting digital output therefrom. The selective inversion may be applied to alternate rows or groups of rows of the pixel data, and may be applied differently to different frames of the pixel data. These techniques result in column fixed pattern noise being modulated in a manner which makes the noise less apparent to the eye, and which facilitates subsequent cancellation of the noise.