Re: Accurate edge detection?

On Jul 20, 2:24=A0pm, "Science.Medical.Imaging List"
<pixel.to.l...@[EMAIL PROTECTED]
> wrote:
> On Jul 19, 7:44=A0am, "aruzinsky" <aruzin...@[EMAIL PROTECTED]
>
>
>
>
>
> cathexis.com> wrote:
> > For some reason, my Google Usenet ****tal is not automatically
producing
> > quotes on my reply to your post therefore I have done it manually.
>
> > "About the last part: are you sure most of the influence of 'optics,
> > sensor size and shape,
> > demosaicing, and size reduction' can be represented by a linear
> > transformation on acquired values?
>
> > I would think you meant not 'represented' but 'estimated'.
>
> > I would be really interested in knowing about any existing (published)
> > proofs in sup****t of your response."
>
> > It is not a linear transformation on "acquired values," y, but on x
whi=
ch
> > represents
> > a higher resolution discrete image that =A0approximates the continuous
> > (infinite resolution) image falling on the sensors. =A0x' is an
estimat=
e of
> > x. =A0Depending on the estimation method, x' may or may not be a
linear
> > function of observations, y. =A0
>
> > The matrix A represents convolution and decimation and is not
invertibl=
e.
> > It is well known that most, if not all, optical effects are
convolution=
s, a
> > linear transformation. Possibly the convolution kernel is a function
of
> > spatial coordinate (as in the case of the bad Hubble telescope lens)
bu=
t
> > it still can be represented by a linear transformation, A. =A0The
effec=
t of
> > pixel sensor size and shape is represented by continuous convolution
> > followed by decimation which again can be incor****ated into A.
=A0Some,=
 but
> > not all cases of demosaicing are also linear transformations.
>
> > --
> > Message posted
usinghttp://www.talkaboutgraphics.com/group/sci.image.pr=
ocessing/
> > More information athttp://www.talkaboutgraphics.com/faq.html
>
> This makes more sense now. Your earlier post suggested (perhaps it was
> the words) that all optical effects can be represented by a
> combination of linear transformations. That was hard to understand. It
> is more reasonable to say that 'some' of the optical effects can be
> represented as linear transformations.- Hide quoted text -
>
> - Show quoted text -

I was suggesting that, but I am not knowledgeable of every possible
optical effect.  Name one optical effect that can't be represented by
a linear transformation.