Re: help in interpreting edge detection threshold criteria

From: Martin Leese (please_at_see.Web.for.e-mail.INVALID)
Date: 11/16/04 

Date: Mon, 15 Nov 2004 20:50:30 -0700
To: Pushker Pradhan <pushkar@erc.msstate.edu>

Pushker Pradhan wrote:
> I'm referring AK Jain "Fundamentals of Digital Image Processing" to
> implement edge detection. The author first asks to compute the image
> gradient (g) by filtering with the (Sobel) filters. I've done this.
> The threshold is selected as follows "Typically, t may be selected using the
> cumulative histogram of g(m,n) so that 5 to 10% of pixels with largest
> gradients are declared as edges."
> Can someone explain to me how the cum. histogram will help?

Ignore the words and look at the meaning. The author
defines edges as pixels with the largest gradient.
Whether you find these via a Cumulative Distribution
Function or some other way is irrelevant. 

-- 
Regards,
Martin Leese
E-mail: please@see.Web.for.e-mail.INVALID
Web: http://members.tripod.com/martin_leese/