title: Image Modification (cropping and de-skewing) in C#
body: <p>With a mobile device I take a picture of a flat light object on a dark surface. (for instance a coupon clipped out of a newspaper).</p>
  
  <p>The image is then run through a brightness/contrast filter.  If it is too dark, vital components are left out.  If it is too bright, the writing on the coupon is lost.</p>
  
  <p>This image is then converted into a bitonal image.  Any pixel that is 50% or more dark is converted to black, everything else is white. (done)</p>
  
  <p>I am left with a skewed bitonal image (think of a white trapezoid inside a larger rectangle with a black background).</p>
  
  <p>I need to figure out how to crop the image - which when it's on a black background is easier than when it's on a white background.   Then, I have to de-skew the image so it is rectangular instead of trapezoidal, while attempting to preserve aspect.</p>
  
  <p>The end result should be a nicely cropped, bitonal, readable image of the coupon.</p>