Re: Accurate edge detection?

On Jul 22, 8:04=A0am, slus...@[EMAIL PROTECTED]
 wrote:
>
> Thank you for your interest and offer to review some sample images.
> Unfortunately, our concern is not on the software or algorithmic side,
> but on the optical side. =A0As I mentioned in my original post:
>
> "Does anyone have references they can point to (or their own
> pesuasive
> arguments) that describe where the true edge location should be
> relative to the edge image function?"
>

I already did.  What is wrong with you?

>
> I also mentioned that I originally posted to sci.optics, then added
> sci.image.processing because I thought the folks here might be more
> aware of relavent references. =A0The (apparently) commonly held belief
> that the maximum slope of the edge image, or the midpoint between the
> maximum and minimum grey level values of the edge image corresponds to
> the true edge location seems unmotivated or unsup****ted to me, even
> though it "feels" like common sense. =A0

That is an algorithm, albeit a really stupid one that is not common
sense, so don't tell me that you are not interest in algorithms.
Furthermore, that is not a commonly held belief, e.g., it is common
knowledge that shock filters sharpen an edge around the inflection
point (the inflection point is preserved) and nobody, I know of,
pretends that shock filtering is deconvolution.

> We have also performed bench
> experiments that suggest that neither the max. slope nor the grey
> level midpoint corresponds to the true edge, with errors being in the
> range of 0.2 to 0.45 pixels in the experimental set up we used.

I hope my tax money didn't fund that busy work.

>=A0We
> are continuing our own investigation, but I have to believe that
> someone has already done this at some time and published their
> results. =A0I'd love to find out that our own efforts at inventing the
> wheel are unecessary. :-)
>

I already gave you a reference to a relatively simple algorithm that
might do better than 0.2 pixels.   It would be foolish not to try it.