Brian thanks for the quick reply. I looked at the script and based upon the comments within it I don't think it's going to work.
"I have tried this function to get DPI value of an image that
I generated using Photoshop and worked as expected but failed
to get DPI value from an image from any digital camera."
The images that are being uploaded are coming from digital cameras. Perhaps the way DPI is written when the image is created with a digital camera is different than with Photoshop.
I'm not a digital image or photoshop expert so any help / ideas is appreciated.