title: Library or approach to extract RGB channels values in RAW image
body: <p>I'm searching for a solution for image comparison for different purposes.
  To make it possible to analyze, I need access to every pixel channels values.
  For example: RAW format which supported by a lot of cameras.</p>
  
  <p>*
  Is there some open source library to get access to channels,
  or is it possible to extract it directly as byte values?<br>
  *
  Currently I'm using bitmap_image reader (<a href="https://github.com/ArashPartow/bitmap" rel="nofollow noreferrer">https://github.com/ArashPartow/bitmap</a>), but not a good idea to convert everytime raw image bo BMP to analyze, I've related <a href="https://github.com/MaksymT17/aquamarine" rel="nofollow noreferrer">repo added to github</a>, it kind of library written on C++14</p>
  
  <p>Please suggest fastest way to access to data of image, thanks.</p>