From: mikko.syrjalahti@nospam.fi   
      
   sgpopticsguru@gmail.com writes:   
      
   > I repeat the test for various exposure durations under the same light   
   > and do a linear regression on pixel values. The linearity of the   
   > pixels are very good but they do not cross from zero, the regression   
   > line has a DC offset.   
      
   There's a bias voltage in the sensor output signal by both the   
   chip amplifiers and purposefully added so that AD converter   
   does not have to start from zero, where it may be non-linear.   
      
   This is removed in astronomy by taking 'bias images' in dark with   
   zero exposure time and substracting this from the image.   
      
   --   
   Mikko OH2HVJ   
      
   --- SoupGate-Win32 v1.05   
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