Another method of measuring the radial sweep I(r) for single fluorescent spots, more complicated but more precise, is to use many circles, centered on the target spot, with different diameters (i.e., the distance from the spot center, r) spaced in an increment of 1pixel. The average intensity in each circle can be independently measured, among which I(0) just reflects the intensity of the center of the target spot. All measurements could be used to construct the radial intensity distribution against different r values. This method was used in Zenisek's paper (2002, neuron), and you could find some details in his paper which has been attached to this mail.
the profiles along each radius "by hand". For example:
>Dear Liu:
> I don't know if this could be of help, but
> there is a plug-in called "radial profile" which maybe could help you.
>
> fjam
>
>"Liu, Dongfang (NIH/NIAID) [E]" <
[hidden email]> escribió:
> Dear friends,
>I am new user of Image J.
>I am sorry to bother you.
>I am looking for your help about the analysis of
>"radial intensity distribution" . The radial
>intensity distribution I(r) of the flourescence
>dot was fit for each frame with a nonlinear
>Levenberg-Marquardt routine to the
>Gaussian:I(r)=Io exp(-R^2/w^2) +BG, where R is
>the distance of each pixel to the center of
>mass. The fitting parameters are Io, w, and BG,
>where Io is the peak intensity, BG is the
>background intensity, and w is the measure of
>the width (the Gauss width). It is very
>important for us to get the peak intensity and
>width. some people suggest me to use Plot Profile(Analyze -> Plot.
>But I think the "plot profile" is not good.
>Because the concept of "plot profile"---Displays
>a two-dimensional graph of the intensities of
>pixels along a line within the image. The x-axis
>represents distance along the line and the
>y-axis is the pixel intensity. For rectangular
>selections, displays a "column average plot",
>where the x-axis represents the horizontal
>distance through the selection and the y-axis
>the vertically averaged pixel intensity
>I was confused that how to calculate the "radial
>intensity distribution" in Image Pro Plus or
>Image J or other software. Could you help me?
>Advice would be greatly appreciated.
>I am looking forward to your reply.
>
>Thank you very much.
>Best regards
>df
>
>
> > ----------
> > From: Gabriel Landini
> > Reply To: List IMAGEJ
> > Sent: Friday, March 3, 2006 12:10 PM
> > To: List IMAGEJ
> > Subject: Re: Image transform
> >
> > On Friday 03 March 2006 16:25, Liu, Dongfang (NIH/NIAID) [E] wrote:
> > > Thank you for your help.
> > > Yes, the system is a miroscope. Could you tell what other optics I should
> > > consider to calibrate a image?
> >
> > No, I couldn't because I do not know what
> kind of optics your microscope has.
> >
> > You have to do this:
> >
> > > > You need to put a known
> > > > sized object under your imaging system
> and see how many pixels it spans.
> > > > Then you estimate the size of your pixels
> dividing the known size of your
> > > > object by the number of pixels it occupies.
> >
> > Cheers,
> >
> > Gabriel
> >
> >
>
>
>
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>
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