Edge detection: Difference between revisions

Revision as of 01:18, 26 October 2005

Revision as of 02:02, 26 October 2005

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=== Calculating the 2nd derivative ===

Some other edge-detection operators are based upon the 2nd derivative of the intensity. This is essentially the rate of change in intensity gradient and is best at detecting lines. :- asAs noted above, a line is a double edge, hence we will see an intensity gradient on one side of the line, followed immediately by the opposite gradient on the opposite site. Therefore we can expect to see a very high change in intensity gradient where a line is present in the image. To find lines, we can search the results for zero-crossings of the change in gradient.

If ''I''(''x'') represents the intensity at point ''x'', and ''I''′′(''x'') is the second derivative at point ''x'':