Re: Spatial frequency

[Baggerly, ROY G]

Did you receive any information from the NIH group? This sounds like
some of the things I might be interested in and I would like to hear
what others say. Thanks.

Roy G. Baggerly
M&PT
TEL:  [phone]
FAX: [phone]

"It is clearly the perception of failure in existing technology
 that drives inventors, designers, and engineers to modify what
others may find perfectly adequate, or at least useable."
Evolution of Useful Things

-----Original Message-----
From: Simon Rigoulot [mailto:[hidden email]]
Sent: Friday, November 04, 2005 12:53 AM
To: [hidden email]
Subject: Spatial frequency

My name is Simon Rigoulot and I would want to compare groups of pictures

according to their spatial frequency.
More precisely, I would want, for different bands of spatial frequency,
and
after a FFT or a wavelet transformation, to measure the energy of these
bands of spatial frequency and after that, compare these energies (with
ANOVA by example).

I Would want to know if it was possible with imageJ and if yes, the way
to
obtain that.

Thanks for your attention

Simon Rigoulot

[dksamuel]

can a ImageJ read a RGB photo (taken by a cheap USB Camera) and filter it to
show only the colors between 2 wavelengths (say between 465 and 495 nm, this
is useful for filtering based on emission and excitation spectra of
Molecular Beacons) or do I need special cameras which are spectrally aware,
to capture and anlayse this information, thanks Samuel, Virologist India

On 11/17/05, Baggerly, ROY G <[hidden email]> wrote:

>
> Did you receive any information from the NIH group? This sounds like
> some of the things I might be interested in and I would like to hear
> what others say. Thanks.
>
> Roy G. Baggerly
> M&PT
> TEL: [phone]
> FAX: [phone]
>
> "It is clearly the perception of failure in existing technology
> that drives inventors, designers, and engineers to modify what
> others may find perfectly adequate, or at least useable."
> Evolution of Useful Things
>
> -----Original Message-----
> From: Simon Rigoulot [mailto:[hidden email]]
> Sent: Friday, November 04, 2005 12:53 AM
> To: [hidden email]
> Subject: Spatial frequency
>
> My name is Simon Rigoulot and I would want to compare groups of pictures
>
> according to their spatial frequency.
> More precisely, I would want, for different bands of spatial frequency,
> and
> after a FFT or a wavelet transformation, to measure the energy of these
> bands of spatial frequency and after that, compare these energies (with
> ANOVA by example).
>
> I Would want to know if it was possible with imageJ and if yes, the way
> to
> obtain that.
>
> Thanks for your attention
>
> Simon Rigoulot
>

[H. Gluender]

Dear Samuel,

you may answer your question by taking a closer look at what RGB
really means and how such signals come into existence in your camera.

>can a ImageJ read a RGB photo (taken by a cheap USB Camera) and filter it to
>show only the colors between 2 wavelengths (say between 465 and 495 nm, this
>is useful for filtering based on emission and excitation spectra of
>Molecular Beacons) or do I need special cameras which are spectrally aware,
>to capture and anlayse this information, thanks Samuel, Virologist India

In fact your color camera has tiny color filters on top of its light
sensitive elements (pixels). Most often, half of the elements are
covered by green filters and the remaining two quarters are covered
by red and blue filters respectively. These three filter types show
more or less overlapping spectral responses with peak transmissions
-- of course -- in the green, red and blue.

If you need high color spectral resolution you may use a spectrometer
type camera or a b&w-camera together with appropriate interference
filters.

Best
--


                   Herbie

          ------------------------

          <http://www.gluender.de>