Re: Accurate edge detection?

On Jul 22, 5:19=A0am, Andrew_M <m...@[EMAIL PROTECTED]
> wrote:
> This is not a simple task, even if you have opaque flat object and a
> uniform back light behind it. Do not try solve really complicated prob
> using simple methods. Let's try to imagine opague circle instead of
> your knife. Lens and scanning system transforms this source object to
> some grayscale image. Where the true edge should be placed, depends on
> the source circle radius, savvy? It means, as a matter of fact, that
> you shouldn't think about it as about an "edge detection problem".
> This is the problem of restoration of a transformed image, and,
> unfortunately, this is an incorrect one. Lots of very different source
> images may produce similar results after transforming, so some
> regularization is a must. It is possible for example, if you have an
> opaque object with more or less smooth edges. What kind of objects do
> you actually have? If you really need some assistance, send me some
> sample image (not very big- my Net is very slow).

Andrew,

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

Thanks again,

Spencer