Patent ID: 7525584
Filing Date: 2009-04-28
Classification: H04N

Abstract:
1. A computer-implemented method for determining from an input color filter array (CFA) sampled image, an edge direction, the method comprising: calculating for a current missing green pixel, interpolation errors in an East-West (EW) direction at known neighboring green pixels, and averaging the EW interpolation errors to obtain an EW error; calculating for the current missing green pixel, interpolation errors in a North-South (NS) direction at known neighboring green pixels, and averaging the NS interpolation errors to obtain a NS error; and selecting a direction indicated by a minimum of the EW error and the NS error as the edge direction; wherein the selected edge direction and the sampled image, which includes a green channel (G) of green pixels, a red channel (R) of red pixels, and a blue channel (B) of blue pixels, are used to interpolate missing green pixels at red and blue locations in the green channel by: for the missing green pixel, interpolating a difference image comprising the G-B if the missing green pixel is in a blue location, or G-R if the missing green pixel is in a red location, in the selected edge direction; in the blue channel, estimating missing blue pixels in green pixel locations using linear interpolation of the blue pixels in the blue channel in the selected edge direction; and in the red channel, estimating the missing red pixels in green pixel locations using linear interpolation of the red pixels in the red channel in the selected direction, thereby providing an interpolated full green channel in which all missing green pixels have an interpolated value; wherein the sampled image and the full green channel are used to correct the green channel by: calculating the EW and NS interpolation errors for each pixel in the full green channel; averaging neighboring EW and NS errors at each green pixel; selecting the green local edge direction EW or NS based on the EW and NS average errors having a smallest value; estimating the green pixels at blue pixel locations using linear interpolation of G-B in the selected direction, and wherein the missing blue pixels are interpolated in the selected direction; and estimating the green pixels at red pixel locations using linear interpolation of G-R in the selected direction, and wherein the missing red pixels are interpolated in the selected direction.