From: luweitest@address.invalid   
      
   On 2015-10-27 7:13, RichD wrote:   
   > At an image processing seminar last week, I saw a startling presentation.   
   > The speaker noted that we cannot measure phase at optical wavelengths,   
   > hence costs a major loss of information.  To illustrate, he displayed two   
   > face photos, then swapped the phase, with no modification of the   
   > magnitudes.  The faces switched places, with slight distortion!   He's   
   > researching algorithms to recover phase.   
   >   
   > Which made me wonder: what 's the highest frequency where we can   
   > measure phase, and with what accuracy?   
   >   
   > Also, a theoretical question manifests - why is it, that most of the   
   > information is in the phase?    You'd expect 50-50.   
   >   
   Image is spatial distribution of EM wave, so the information includes   
   amplitude & frequency (rendered as spectra), phase, and their spatial   
   distribution. Phase carries least information compared to others.   
   Holography uses that information to build 3D images.   
      
   --   
   Regards,   
   Lu Wei   
   PGP key ID: 0x92CCE1EA   
      
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