This takes an image (<a href="https://en.wikipedia.org/wiki/Image:Barns_grand_tetons.jpg" class="extiw" title="en:Image:Barns grand tetons.jpg">Image:Barns grand tetons.jpg</a>) and displays the red, green and blue elements extracted from it.  Note that the white snow is composed of strong red, green and blue; the brown barn is composed of strong red and green with little blue; the dark green grass is composed of strong green with little red or blue; and the light blue sky is composed of strong blue and moderately strong red and green.  Based on the (public domain) photo <a href="https://en.wikipedia.org/wiki/Image:Barns_grand_tetons.jpg" class="extiw" title="en:Image:Barns grand tetons.jpg">Image:Barns grand tetons.jpg</a>. Code above and resulting output by Mike1024.
<ul><li><a href="//commons.wikimedia.org/wiki/File:Barn_grand_tetons_rgb_separation.jpg" title="File:Barn grand tetons rgb separation.jpg">Barn_grand_tetons_rgb_separation.jpg</a>: Original uploader was <a href="https://en.wikipedia.org/wiki/User:Mike1024" class="extiw" title="en:User:Mike1024">Mike1024</a> at <a class="external text" href="https://en.wikipedia.org">en.wikipedia</a></li>
<li>derivative work: <a href="//commons.wikimedia.org/w/index.php?title=User:NuclearDuckie&amp;action=edit&amp;redlink=1" class="new" title="User:NuclearDuckie (page does not exist)">NuclearDuckie</a> (<a href="//commons.wikimedia.org/wiki/User_talk:NuclearDuckie" title="User talk:NuclearDuckie"><span class="signature-talk">talk</span></a>)</li></ul>
2011-01-27 12:28
<ul><li><a href="//commons.wikimedia.org/wiki/File:Barn_grand_tetons_rgb_separation.jpg" title="File:Barn grand tetons rgb separation.jpg">Barn_grand_tetons_rgb_separation.jpg</a></li></ul>