Patent ID: 7801384
Filing Date: 2010-09-21
Classification: H04N

Abstract:
1. A method for correcting column fixed pattern noise (FPN) in pixel image signals from an image sensor comprising an array of active pixel elements arranged in rows and columns, with at least one of the rows comprising optically masked pixels so that output image signals obtained therefrom represent a column FPN; and a respective output circuit connected to each column of the array of active pixels for reading the pixel image signals therefrom, each output circuit comprising a pair of sampling capacitors, and a sampling switch for applying pixel voltages to the pair of sampling capacitors, the method comprising: recording the column FPN for each column from the at least one row of optically masked pixels using an image processing circuit; recording the pixel image signals from the array of active pixels using the image processing circuit; calculating a mean column-wise FPN from the recorded column FPN for each column using the image processing circuit; and subtracting the mean column-wise FPN column-wise from the pixel image signals using the image processing circuit; recording the column FPN comprising operating the sampling switch for applying a value of the output image signal from the at least one row of optically masked pixels to each of the sampling capacitors, and utilizing a difference of the values of the output image signal on each sampling capacitor as the column FPN value for each column.