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Re: Line profile seems to filter data

Posted by Michael Schmid on Nov 12, 2018; 6:49pm
URL: http://imagej.273.s1.nabble.com/Line-profile-seems-to-filter-data-tp5021433p5021445.html

Hi Mark,

unfortunately that mircosoft site did not allow me to download the files
to disk [only to a OneDrive account, but I have none], but I could see a
preview of the image and line profiles. Maybe have a solution:

If your line is close to horizontal, but not exactly horizontal, it will
start at an integer pixel position. Further pixels are sampled at
distances of 1, 2, 3, 4, etc.; these distances are measured along the
line, i.e., under an angle. For a non-horizontal line these positions
will be at non-integer pixel positions, and ImageJ will use interpolated
values. If the data are rather noisy or you have large variations
between neighboring pixels, the interpolated values will look more
smooth than the actual data.

You can disable interpolation in Edit>Options>Plots
("Interpolate Line Profiles").

Alternatively, you can hold the shift key while drawing the line to make
sure it is exactly horizontal.


Michael
________________________________________________________________
On 12.11.18 19:15, msenko wrote:

> https://bgitech-my.sharepoint.com/:f:/g/personal/msenko_genomics_cn/EudbH2S4RAtEhayyDauqrloBuJ6UiUowB-bNU_h_2wv2Ig?e=V4iUwU
> <https://bgitech-my.sharepoint.com/:f:/g/personal/msenko_genomics_cn/EudbH2S4RAtEhayyDauqrloBuJ6UiUowB-bNU_h_2wv2Ig?e=V4iUwU>
>
> Here is a link to a directory that contains an image and a macro that
> analyzes it. A plot is produced which shows the profile generated from a
> line and a box.
>
> <http://imagej.1557.x6.nabble.com/file/t382159/Profiles.jpg>
>
> We tried to recreate this problem with a simple noise image generated in
> ImageJ, but the problem doesn't show up. There must be something specific
> about our data.....
>
>
>
> --
> Sent from: http://imagej.1557.x6.nabble.com/
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>

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