title: Image DPI Explained
body: <p>Attempting to write a definition of DPI has lead me to:</p>
  
  <p>DPI (dots), PPI (points), LPI (lines) all refer to the same concept hereafter referred to as DPI.</p>
  
  <p>DPI is a device dependent measurement.  It says, "This is the resolution of this device."</p>
  
  <p>Vector based files are not tied to any one DPI (they expand and contract to conform to a certain resolution).</p>
  
  <p>When that vector based file is rendered to a "bitmap" based format - (bmp, png, tiff, jpg) etc... that "bitmapped" file is created at a certain DPI for printing (or display) on "banding" or "scanline" based devices that output at that specific DPI.</p>
  
  <p>Now, some would argue that DPI does not exist in "bitmapped" based files.</p>
  
  <p>I'm looking for a definition of DPI and how or why it would be considered to not exist in a bitmapped image?</p>