Re: Segmented line shifting when splining in subpixel mode
Posted by Michael Schmid on Dec 02, 2013; 5:44pm URL: http://imagej.273.s1.nabble.com/Segmented-line-shifting-when-splining-in-subpixel-mode-tp5005762p5005772.html
Hi Pierre,
did you try to update ImageJ to 1.48g or the latest daily build?
The accuracy of line displays has improved a lot in the recent versions.
If there are still problems, please post to the list again.
Michael
________________________________________________________________
On Dec 2, 2013, at 15:58, Pierre1981 wrote:
> Hello,
>
> I observed something which is a little bit puzzling when using sub-pixel
> resolution:
>
> 1/ I check "true" for Sub-pixel resolution in Edit>Options>Profile Plot
> Options
> 2/ I make a segmented line selection:
>
> <http://imagej.1557.x6.nabble.com/file/n5005762/new_selection.jpg>
>
> 3/ I apply "Spline Fit" by checking the Spline Fit check box:
>
> <http://imagej.1557.x6.nabble.com/file/n5005762/spline_copy.jpg>
>
> The result is that segment is overall shifted in one direction by about one
> pixel (on the example "anchor points" are translated toward the left, which
> does not happen out of sub-pixel mode).
> However, if I then uncheck Spline Fit, the resulting segmented line is
> different from the first selection I made:
>
> <http://imagej.1557.x6.nabble.com/file/n5005762/after_spline.jpg>
>
> 4/ If now I interpolate the spline fit with one pixel interval, I again see
> quite some difference from the original spline, with what seems to be a
> global selection translation (sometimes one or two pixel distant from the
> original selection; this appears also without sub-pixel resolution).
>
> <http://imagej.1557.x6.nabble.com/file/n5005762/interpolate.jpg>
>
> In my application this is a little bit annoying, because I look at intensity
> along curved lines and I need to adjust the selection after splining and
> after interpolating.
>
> Is all this normal, or shouldn't there be a need to be fixed?
>
> Kind regards,
> Pierre
>
>
>
>
> --
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>
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