Pixel intensities at equidistant sample points along selection

[Richard Mort]

Hi can anyone help me with this?
I'd like to do a profile plot that returns pixel intensities at
equidistant sample points along a selection and I'd like to be able to
specify the distance.
Cheers
R
--
Dr Richard Mort
MRC Human Genetics Unit
Western General Hospital
Crewe Road
Edinburgh
EH4 2XU, UK.

Phone: [phone] x 3205
Fax: [phone]

[Wayne Rasband]

On Nov 14, 2008, at 9:30 AM, Richard Mort wrote:

> Hi can anyone help me with this?
> I'd like to do a profile plot that returns pixel intensities at
> equidistant sample points along a selection and I'd like to be able to
> specify the distance.

The Edit>Selection>Fit Spline command, when called with a ""straighten"
option, converts a line selection to one with points spaced one pixel
apart. Here is an example:

   newImage("Test", "8-bit Black", 480, 480, 1);
   makeLine(77,81,186,97,246,165,248,236,180,310,88,292);
   getSelectionCoordinates(x,y);
   print("points: ", x.length);
   run("Measure");
   print("length: "+getResult("Length", nResults-1));
   run("Fit Spline", "straighten");
   getSelectionCoordinates(x,y);
   print("points: ", x.length);
   run("Measure");
   print("length: "+getResult("Length", nResults-1));

-wayne

[Richard Mort]

I'm sorry I can't follow this please can you explain? I'd like to be
able to specify 'sample every n pixels' for any selection.
Kind regards
Richard

Wayne Rasband wrote:

> On Nov 14, 2008, at 9:30 AM, Richard Mort wrote:
>
>> Hi can anyone help me with this?
>> I'd like to do a profile plot that returns pixel intensities at
>> equidistant sample points along a selection and I'd like to be able to
>> specify the distance.
>
> The Edit>Selection>Fit Spline command, when called with a ""straighten"
> option, converts a line selection to one with points spaced one pixel
> apart. Here is an example:
>
>   newImage("Test", "8-bit Black", 480, 480, 1);
>   makeLine(77,81,186,97,246,165,248,236,180,310,88,292);
>   getSelectionCoordinates(x,y);
>   print("points: ", x.length);
>   run("Measure");
>   print("length: "+getResult("Length", nResults-1));
>   run("Fit Spline", "straighten");
>   getSelectionCoordinates(x,y);
>   print("points: ", x.length);
>   run("Measure");
>   print("length: "+getResult("Length", nResults-1));
>
> -wayne

--
Dr Richard Mort
MRC Human Genetics Unit
Western General Hospital
Crewe Road
Edinburgh
EH4 2XU, UK.

Phone: [phone] x 3205
Fax: [phone]

[Harry Parker]

If all you want to do is sample the image every n pixels, you can just just subsample the image
 (menu Image->Scale... or Ctrl-E) and do a normal profile plot of a line on the resulting image.

 
--
Harry Parker
Senior Imaging Systems Engineer
Digital Imaging Systems, Inc.



----- Original Message ----
From: Richard Mort <[hidden email]>
To: [hidden email]
Sent: Monday, November 17, 2008 4:30:31 AM
Subject: Re: Pixel intensities at equidistant sample points along selection

I'm sorry I can't follow this please can you explain? I'd like to be able to specify 'sample every n pixels' for any selection.
Kind regards
Richard

Wayne Rasband wrote:

> On Nov 14, 2008, at 9:30 AM, Richard Mort wrote:
>
>> Hi can anyone help me with this?
>> I'd like to do a profile plot that returns pixel intensities at equidistant sample points along a selection and I'd like to be able to specify the distance.
>
> The Edit>Selection>Fit Spline command, when called with a ""straighten" option, converts a line selection to one with points spaced one pixel apart. Here is an example:
>
>   newImage("Test", "8-bit Black", 480, 480, 1);
>   makeLine(77,81,186,97,246,165,248,236,180,310,88,292);
>   getSelectionCoordinates(x,y);
>   print("points: ", x.length);
>   run("Measure");
>   print("length: "+getResult("Length", nResults-1));
>   run("Fit Spline", "straighten");
>   getSelectionCoordinates(x,y);
>   print("points: ", x.length);
>   run("Measure");
>   print("length: "+getResult("Length", nResults-1));
>
> -wayne

-- Dr Richard Mort
MRC Human Genetics Unit
Western General Hospital
Crewe Road
Edinburgh
EH4 2XU, UK.

Phone: [phone] x 3205
Fax: [phone]