Light level adaptive filter and method

Abstract

An example method includes determining an estimated pixel noise parameter based on a signal level of a first pixel of the first frame of pixel data; determining a difference between the signal level of the first pixel and at least a signal level of a second pixel; obtaining a filtered pixel based at least in part on a comparison of the difference to the estimated pixel noise parameter; and outputting the filtered pixel to an output frame of filtered pixel data.

We claim: 
     
         1 . A method comprising:
 receiving a first frame of pixel data;   determining an estimated pixel noise parameter based on a signal level of a first pixel of the first frame of pixel data;   determining a difference between the signal level of the first pixel and at least a signal level of a second pixel;   obtaining a filtered pixel based at least in part on a comparison of the difference to the estimated pixel noise parameter; and   outputting the filtered pixel to an output frame of filtered pixel data.   
     
     
         2 . The method of  claim 1 , wherein the method is performed by a first adaptive noise filter of a plurality of adaptive noise filters. 
     
     
         3 . The method of  claim 2 , further comprising:
 providing the output frame of filtered pixel data to a second adaptive noise filter of the plurality of adaptive noise filters.   
     
     
         4 . The method of  claim 1 , further comprising:
 outputting pixel noise corresponding to the filtered pixel to a noise output frame.   
     
     
         5 . The method of  claim 4 , further comprising providing the noise output frame of pixel noise data from a first adaptive noise filter to a second adaptive noise filter. 
     
     
         6 . The method of  claim 1 , wherein obtaining the filtered pixel comprises:
 determining, based on the comparison, an amount of the signal level of the first pixel to allow to pass through a filter; and   obtaining the filtered pixel based on the amount of the signal level of the first pixel to allow to pass through the filter.   
     
     
         7 . The method of  claim 6 , wherein determining, based on the comparison, the amount of the signal level of the first pixel to allow to pass through the filter comprises:
 determining a noise standard deviation corresponding to the signal level of the first pixel; and   using the noise standard deviation to determine a percent of the difference between the signal level of the first pixel and at least the signal level of the second pixel that is allowed to pass through the filter.   
     
     
         8 . The method of  claim 7 , wherein obtaining the filtered pixel based on the amount of the signal level of the first pixel to allow to pass through the filter comprises:
 adding the percent of the difference and a value of the second pixel to obtain the filtered pixel.   
     
     
         9 . The method of  claim 1 , wherein:
 the second pixel is at a same location in a previous frame captured prior in time to a capture of the first frame as a location of the first pixel in the first frame.   
     
     
         10 . A system comprising:
 an image sensor configured to capture a first frame of pixel data; and   a processor coupled to the image sensor and configured to implement an imaging pipeline to receive the first frame of pixel data, the imaging pipeline including an adaptive noise filter configured to:
 filter a first pixel using an estimated pixel noise level of the first pixel and using a difference between a signal level of the first pixel and at least a signal level of a second pixel to obtain a filtered pixel; and 
 output a second frame of pixel data including the filtered pixel; 
   the imaging pipeline including a plurality of stages, each of the plurality of stages following a first stage of the plurality of stages being configured to process an input pixel noise frame and configured to output a stage dependent pixel noise frame.   
     
     
         11 . The system of  claim 10 , further comprising:
 a display device coupled to the imaging pipeline to receive an output frame of pixel data output by the imaging pipeline, the display device being configured to display the output frame of pixel data.   
     
     
         12 . A system comprising:
 at least one computer processor that implements an adaptive noise filter configured to:   receive a first frame of pixel data;   determine an estimated pixel noise parameter based on a signal level of a first pixel of the first frame of pixel data;   determine a difference between the signal level of the first pixel and at least a signal level of a second pixel;   obtain a filtered pixel based at least in part on a comparison of the difference to the estimated pixel noise parameter; and   output the filtered pixel to an output frame of filtered pixel data.   
     
     
         13 . The system of  claim 12 , wherein the adaptive noise filter in included in a plurality of adaptive noise filters. 
     
     
         14 . The system of  claim 13 , wherein the adaptive noise filter is further configured to:
 provide the output frame of filtered pixel data to a second adaptive noise filter included in the plurality of adaptive noise filters.   
     
     
         15 . The system of  claim 12 , wherein the adaptive noise filter is further configured to:
 output pixel noise corresponding to the filtered pixel to a noise output frame.   
     
     
         16 . The system of  claim 15 , wherein the adaptive noise filter is further configured to:
 provide the noise output frame of pixel noise data to a second adaptive noise filter.   
     
     
         17 . The system of  claim 12 , wherein the obtaining the filtered pixel comprises:
 determining, based on the comparison, an amount of the signal level of the first pixel to allow to pass through a filter; and   obtaining the filtered pixel based on the amount of the signal level of the first pixel to allow to pass through the filter.   
     
     
         18 . The system of  claim 17 , wherein the determining, based on the comparison, the amount of the signal level of the first pixel to allow to pass through the filter comprises:
 determining a noise standard deviation corresponding to the signal level of the first pixel; and   using the noise standard deviation to determine a percent of the difference between the signal level of the first pixel and at least the signal level of the second pixel that is allowed to pass through the filter.   
     
     
         19 . The system of  claim 18 , wherein the obtaining the filtered pixel based on the amount of the signal level of the first pixel to allow to pass through the filter comprises:
 adding the percent of the difference and a value of the second pixel to obtain the filtered pixel.   
     
     
         20 . The system of  claim 12 , wherein:
 the second pixel is at a same location in a previous frame captured prior in time to a capture of the first frame as a location of the first pixel in the first frame.