Posted by
Gluender-2 on
Mar 12, 2009; 11:19am
URL: http://imagej.273.s1.nabble.com/Zooming-and-smoothing-tp3693324p3693336.html
Bob,
thanks for providing more details of the problem.
>Herbie,
>>
>>In any case you have to justify the "simulation" of a finer grid...
>>HTH
>>Herbie
>
>Interesting point. The acoustical images are generated on a range
>of scales depending on frequency and the processing algorithm, but
>they always have to end up a certain size to match the optical
>reference image and to look right in PowerPoint, Word, or YouTube.
>I could compute them in that size (I'm giving YouTube 640 x 360 now)
>but it would take longer than it needs to in some cases (low
>frequency). I could scale up the acoustic image without
>interpolation, but then it would look seriously wrong, and would not
>be what I would have gotten by computing every pixel. I convinced
>myself that the band-limited nature of the imaging is consistent
>with the interpolation process, and validated this with some test
>cases. In the tests, the interpolated results matched the detailed
>computation. Application of a deconvolution algorithm makes the
>situation more interesting. It that case, it is possible to
>generate high resolution nonsense.
>
>Bob
>
>
>Robert Dougherty, Ph.D.
>President, OptiNav, Inc.
>4176 148th Ave. NE
>Redmond, WA 98052
>(425)891-4883
>FAX (425)467-1119
>www.optinav.com
>
[hidden email]
1.
Of course I've assumed that your data essentially conforms with the
sampling theorem.
2.
As far as I understand the rest of the story, you want to match
images of different _true_ resolutions (defined by the acquisition
process; wavelength, type of radiation etc.) and display them
together.
3.
This apears to be a situation in which interpolation can make sense.
If these images are of scientific importance you should point out the
numerical values of the various true resolutions.
4.
In this context I still have problems with expressions such as "look
right" or "look seriously wrong". But...
5.
...there is an important aspect:
The usual visual representation of pixel values as blocks introduces
structures that have nothing to do with underlying image information.
That said, it is obvious that interpolation helps avoiding these
alien structures when inspecting and perhaps displaying spatially
discrete images at high magnifications.
6.
Originally this thread dealt with another intention, namely that to
make high resolution selections from interpolated images and this
appears to be scientifically highly problematic, not to say dishonest.
I cite:
"I draw a free hand selection and it creates a zigzag in pixels which makes it
impossible to follow the round. Likewise for the thresholding - the
pixelation is very obvious."
Best
Herbie