Feature extractors may/may not be misinterpreting light/datk background images differently

What steps will reproduce the problem?
1. analyze a light background image with Object Statistics
2. analyze a dark background image with Object Statistics
3. Compare results, in one case, the background pixels are considered
   to be the only object in the image.

What is the expected output? What do you see instead?
  Expected: Logic knows what background and foreground is, by manual  
            selection or analysis. Should not interpret background as  
            objects.

  Observed: By default, only dark background images are correctly 
            analyzed. Light background images are considered to be made   
            up of one object, the background, due to comparison of pixel 
            value to threshold value ie: "if(value > threshold)" .

Please use labels and text to provide additional information.

 Issue discovered while developing ObjectStatistics3D, testing on simple white field images.  Not yet known how many other feature extractors have logic affected by this issue. It is necessary to study their operation and determine what threshold criteria are being used for object extraction.  

Short term fix: All feature extractors should by default prefer to treat 
   images as black field.

Long term fix: A parameter should be built into affected feature    
   extractors allowing for bright/dark field selection accessible from 
   the GUI.

Original issue reported on code.google.com by Jon.Sand...@gmail.com on 14 May 2013 at 4:40

jzhousz / iano

Feature extractors may/may not be misinterpreting light/datk background images differently #57