http://imagej.273.s1.nabble.com/How-is-the-line-plot-profile-generated-tp5015838p5015869.html
'Sub-Pixel Resolution' in the (Profile) Plot options. You may also want to
//and anything else you want to happen at startup, e.g. Binary options, ...
> Dear All,
>
> I wished to add a piece of macro to illustrate the behaviour I observed
> and
> was describing (see below).
>
> Discussing offline with Avital made it clear what happens: pixel values
> are
> represented by the image-coordinate system and this introduces asymmetry -
> let's consider 3 pixels:
> - x=0,y=0 (black)
> - x=0,y=1 (white)
> -x=0,y=2 (black)
>
> If I draw two horizontal lines at y=0.5 and y=2.5. They are both
> equidistant from the white pixel on the image (i.e., it looks symmetric)
> but they are not equidistant in the coordinate system, the line at y=0.5
> is
> only 0.5 pixels far from the while pixel's origin (at x=0,y=1), while the
> line at y=2.5 is 1.5 pixels away. This introduces asymmetry when plot
> profile calculates values.
>
> Would anyone know of a way of producing a symmetric behaviour for plot
> profile?
>
> Thanks for your help,
> All the best,
>
> Emmanuel
>
>
> ===========
>
> The macro below creates a whitish region at the centre of a 17 by 17px
> image, and adds a white pixel at the top of the image as well. It then
> draws two pairs of lines. I would expect the profile for the two pairs to
> be identical because the pixel environment is identical. However, the two
> profiles within each pair are different. e.g., if the line is 0.5 pixel
> above or below a white pixel will yield a very different outcome.
>
> newImage("Untitled", "8-bit Black", 17, 17, 1);
> makeRectangle(8, 8, 1, 1);
> run("Clear", "slice");
> run("Select All");
> run("Gaussian Blur...", "sigma=2");
> makeRectangle(7, 1, 1, 1);
> run("Clear", "slice");
> run("Enhance Contrast", "saturated=0.35");
>
> ///// FIRST PAIR OF PROFILES (left and right to the whitish spot)
> selectWindow("Untitled");
> makeLine(4.5, 5.5, 4.5, 11.5);
> run("Plot Profile");
>
> selectWindow("Untitled");
> makeLine(12.5, 5.5, 12.5, 11.5);
> run("Plot Profile");
>
>
> ///// SECOND PAIR OF PROFILES (top and bottom to the white pixel)
> selectWindow("Untitled");
> makeLine(5.5, 0.5, 9.5, 0.5);
> run("Plot Profile");
>
> selectWindow("Untitled");
> makeLine(5.5, 2.5, 9.5, 2.5);
> run("Plot Profile");
>
> On 10 March 2016 at 10:06, Jan Eglinger <
[hidden email]> wrote:
>
>> Dear Avital and Emmanuel,
>>
>> > On 9 March 2016 at 21:28, Avital Steinberg <
[hidden email]>
>> > wrote:
>> >> Herbie helped me in the other ImageJ forum
>>
>> Let's be nice and link to this discussion, so others can follow:
>>
http://forum.imagej.net/t/how-is-the-plot-profile-calculated/1070>>
>>
>> On 10.03.2016 07:26, Emmanuel Levy wrote:
>>
>>> I would have expected that, by default, only the pixels onto which the
>>> line
>>> is drawn are used and interpolated when calculating the profile. Is
>>> this
>>> non-symmetric behaviour of the interpolation an intended behaviour?
>>>
>>
>> I agree that there are inconsistencies between how lines and segmented
>> line selection are displayed on the image and the measurements of those
>> lines. Please see also my following related post on the forum:
>>
>>
>>
http://forum.imagej.net/t/change-in-pixels-using-reslice-function/999/2?u=imagejan>>
>>
>> I remember previous discussions about rectangular selections and the
>> behavior of the Fill and Draw commands that by now have been fixed. It
>> would be great to have a consistent ROI behavior through all types of
>> selections in ImageJ.
>>
>> Cheers,
>> Jan
>>
>>
>>
>>
>>>
>>> On 9 March 2016 at 21:28, Avital Steinberg <
[hidden email]>
>>> wrote:
>>>
>>> Hi,
>>>> When I use ImageJ's graphical user interface and draw a line and then
>>>> select Analyze, plot profile (with the default settings), I get a plot
>>>> of
>>>> intensities vs. the distance from the beginning of the line. I was
>>>> wondering how the plot is generated, in terms of which pixels in the
>>>> neighborhood are taken into the weighted average, and how the weights
>>>> are
>>>> determined.
>>>>
>>>> Herbie helped me in the other ImageJ forum by suggesting that I plot a
>>>> ramp
>>>> image. Now I can sometimes predict the values that will appear in the
>>>> profile plot. (but only in some simple cases) After experimenting with
>>>> an
>>>> image, I noticed that the plot's x-axis scale changes abruptly from
>>>> 1.5
>>>> to
>>>> 2.0 (for example) and I was wondering if the distance between 2
>>>> adjacent
>>>> points changes when the scale suddenly changes.
>>>>
>>>> Thank you,
>>>> Avital
>>>>
>>>
>
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