Thanks Kees,
you are right and it appears that the behaviour makes sense because the
"Straightener"-mechanism is used in such cases (see the Forum post from
June 2022)!
Great catch
Herbie
:::::::::::::::::::::::::::::::::::::::::::::::::::
Am 08.08.25 um 10:05 schrieb Straatman, Kees (Dr.):
Morning,
I don't think that solves the problem as you should use:
selectImage("Mock");
roiManager("Select", 0);
Roi.setStrokeWidth(2);
roiManager("Update");
roiManager("Multi Plot");
and this gives the same result/problem as the original code.
Some more information can be found at
https://forum.image.sc/t/plot-profile-fits-a-spline-for-no-reason-on-polylines/68768
Depending on what you try to do you could use:
newImage("Mock", "16-bit black", 850, 850, 1);
makeLine(156,486,392,255,683,459);
roiManager("Add");
selectImage("Mock");
roiManager("Select", 0);
Roi.setStrokeWidth(1);
roiManager("Update");
roiManager("multi-measure measure_all one append");
selectImage("Mock");
roiManager("Select", 0);
Roi.setStrokeWidth(2);
roiManager("Update");
roiManager("multi-measure measure_all one append");
Best wishes
Kees
Dr Ir K.R. Straatman FRMS
Advanced Imaging Facility (RRID: SCR_020967)
University of Leicester
http://www.le.ac.uk/advanced-imaging-facility
-----Original Message-----
Sent: 07 August 2025 21:01
To: [email protected]
Subject: Re: Odd behavior from plotprofile
***CAUTION:*** This email was sent from an EXTERNAL source. Think before
clicking links or opening attachments.
Greetings Lance,
did you try
selectImage("Mock");
roiManager("Select", 0);
Roi.setStrokeWidth(2);
roiManager("Multi Plot");
instead?
Best
Herbie
:::::::::::::::::::::::::::::::::::::::::::::
Am 07.08.25 um 20:13 schrieb Davidson, Lance:
Hi All,
Recent efforts to use plotprofile with different linewidths have given some
surpising results where the length changes with the linewidth.
We are using free line ROIs automatically generated by segmentation algorithms.
I've simplified the macro below to do the same thing with a simple two-segment
polyline.
If the line is 1 pixel wide the reported distance is 685 pixels, if the line is
2 pixels wide the distance is 705...
Not only is the plotprofile outcome odd, but the polyline gets "splined".
Any help or workaround would be appreciated.
Best,
Lance
Lance Davidson, MSc, PhD
William Kepler Whiteford Professor of Bioengineering University of
Pittsburgh
//---------------------- offending macro -----------------
newImage("Mock", "16-bit black", 850, 850, 1);
makeLine(156,486,392,255,683,459);
roiManager("Add");
selectImage("Mock");
roiManager("Select", 0);
Roi.setStrokeWidth(1);
run("Plot Profile");
selectImage("Mock");
roiManager("Select", 0);
Roi.setStrokeWidth(2);
run("Plot Profile");
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