US 11,816,858 B2
Noise reduction circuit for dual-mode image fusion architecture
Maxim Smirnov, Portland, OR (US); and Sheng Lin, San Jose, CA (US)
Assigned to APPLE INC., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Feb. 10, 2021, as Appl. No. 17/173,094.
Prior Publication US 2022/0254050 A1, Aug. 11, 2022
Int. Cl. G06T 7/90 (2017.01); G06T 3/40 (2006.01); G06T 5/00 (2006.01); G06T 7/70 (2017.01)
CPC G06T 7/70 (2017.01) [G06T 3/4007 (2013.01); G06T 5/002 (2013.01); G06T 7/90 (2017.01); G06T 2207/20028 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A noise reduction circuit, comprising:
a photometric distance calculator circuit configured to determine distances between a center pixel of a pixel block to a set of neighbor pixels of the pixel block, the pixel block comprising raw image data associated with a raw image, wherein the center pixel is of a first color channel, and wherein the set of neighbor pixels is selected from the pixel block based upon the first color channel, and comprises one or more pixels of a color channel other than the first color channel; and
a bilateral filter circuit coupled to the photometric distance calculator circuit and configured to:
analyze color values of the set of neighbor pixels to determine an edge direction of a set of edge directions associated with the pixel block, wherein a color value of each pixel of the one or more pixels of the set of neighbor pixels of the color channel other than the first channel is determined by interpolating color values of at least two adjacent pixels of the pixel block that are of the first color channel;
determine a set of filter taps for the set of neighbor pixels by processing the edge direction and one or more of the distances determined by the photometric distance calculator circuit; and
apply the determined set of filter taps to corresponding color values of the set of neighbor pixels to obtain a filtered pixel value of the center pixel.