Sample wrapped image

[Luca Ortolani]

Hello,

I'm working in developing a plugin for ImageJ, to digitally  
reconstruct transmission electron holograms. I've implemented in the  
plugin an unwrapping procedure to remove phase jumps from  
reconstructed phase images.

The plugin has not been released yet, but is working well with  
holograms and phase maps from TEM images and I'm interested in  
testing the unwrap algorithm on images from different sources: like  
magnetic resonance or satellite radar images affected by the same  
phase jumps problem.

I'm wondering if anyone could kindly send me some wrapped phase  
images for testing. The current release of the plugin is availabe at  
http://www.bo.imm.cnr.it/~ortolani/index.php?sec=holoj

Thank you in advance.


Luca Ortolani - Ph.D. Student

CNR-IMM Bologna
Via Gobetti, 101
40129 Bologna (Italy)

E-mail: [hidden email]
Phone: [phone]
Fax: [phone]

[Joachim Wesner]

Hi Luca,

I already tried to contact you via personal mail as I also will be several
times in Italy (Brescia and probably also Bologna) this year,
I´m very interested in this work and would like to discuss more about this
with you.

I already tried your latest plugin and could not yet get the results I
expected, resp. it does not work better or even worse as
my own quality-guided path-following plugin (and it´s also not faster!)
:-((((

When the paper of 1st paper of Shofield and Zhu came out we were very
baffled, because it really seemed not to work on our typical
interferogramms which
always have considerable overall tilt and the "Shofield and Zhu" seems to
imply some special boundary conditions that are incompatible with that.
What also
surprises is that the paper never ever cites THE "2D unwrapping bible" by
Ghiglia and Pritt, which goes at length at explaing that "unweighted" FFT
based methods
must fail if tilt and residues (poles) are in the image, just the thing
that always make phase unwrapping difficult. So why should it not apply to
the "Shofield and Zhu"
algorithm? We could not understand.

To make confusion even greater, shortly later Volkov and Zhu came out with
a related algorithm,

"Deterministic phase unwrapping in the presence of noise" by Vyacheslav V.
Volkov and Yimei Zhu

Optics Letters, Vol. 28, Issue 22, pp. 2156-2158

which is claimed to be EVEN better, robust, deterministic and automatic,
see for example a more popular presentation:

http://www.laserfocusworld.com/display_article/197346/12/none/none/News/Phase-unwrapping-algorithm-shrugs-off-noise

(IMHO it sounds like it would now be THE ULTIMATE phase unwrapping
algorithm for ever... No need to come up with another one...)

I would be again interested in learning why the above mentioned limitations
should not apply and what exactly the relation is to
the algorithm in the first paper.

I could send you lot´s of interferogramms of the kind we find "difficult"
to unwrap....

Any help greatly appreciated!

Tantissime grazie!

Cordiali saluti

Joachim Wesner
Projektleiter Optik Technologiesysteme


Leica Microsystems CMS GmbH | GmbH mit Sitz in Wetzlar | Amtsgericht
Wetzlar  HRB 2432
Geschäftsführer:  Dr. Stefan Traeger | Dr. Wolf-Otto Reuter | Dr. David Roy
Martyr | Colin Davis


                                                                           
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Hello,

I'm working in developing a plugin for ImageJ, to digitally
reconstruct transmission electron holograms. I've implemented in the
plugin an unwrapping procedure to remove phase jumps from
reconstructed phase images.

The plugin has not been released yet, but is working well with
holograms and phase maps from TEM images and I'm interested in
testing the unwrap algorithm on images from different sources: like
magnetic resonance or satellite radar images affected by the same
phase jumps problem.

I'm wondering if anyone could kindly send me some wrapped phase
images for testing. The current release of the plugin is availabe at
http://www.bo.imm.cnr.it/~ortolani/index.php?sec=holoj

Thank you in advance.


Luca Ortolani - Ph.D. Student

CNR-IMM Bologna
Via Gobetti, 101
40129 Bologna (Italy)

E-mail:            [hidden email]
Phone:             [phone]
Fax:                     [phone]



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