Computerized image analysis software

[S. Bowman]

Hello,

	I am doing a study of the trophic morphology of fathead minnows and I was
wanting to use computerized image analysis software instead of calipers. 
Could anyone suggest an appropriate an relatively inexpensive (<$500)
software package?
Could you please include a list of any specialized hardware that might be
required.

	Thank-you for your time,

	Stephan Bowman