Posted by
Cammer, Michael on
Oct 27, 2016; 3:11pm
URL: http://imagej.273.s1.nabble.com/pixel-size-is-slightly-different-when-dcm-is-saved-as-tif-tp5017492p5017494.html
1. Does changing the units to um or nm fix the problem?
2. Are any of these decimal places significant anyhow? This is out in the angstrom range.
=========================================================================
Michael Cammer, Microscopy Core & Skirball Institute, NYU Langone Medical Center
Cell: 914-309-3270 Office: Skirball 2nd Floor main office, back right
http://ocs.med.nyu.edu/microscopy &
http://microscopynotes.com/-----Original Message-----
From: ImageJ Interest Group [mailto:
[hidden email]] On Behalf Of Herbie
Sent: Thursday, October 27, 2016 8:26 AM
To:
[hidden email]
Subject: Re: pixel size is slightly different when .dcm is saved as .tif
Good day Schebique,
I fear you are reaching the limit of the number representation...
Of course this limit isn't absolute but without changing the Java code, you have to accept it.
Best
Herbie
:::::::::::::::::::::::::::::::::::::::::::
Am 27.10.16 um 13:09 schrieb Ondřej Šebesta:
> Dear ImageJ developers.
>
> I found slightly different results when measuring dicom images and
> their respective .tif form. Let say .dcom is calibrated as 0.139999000 mm/pixel.
> I save it as .tif and it is still this value. But after reopen this
> .tif file pixel size is interpreted as 0.139999003, which leads to a
> slightly different results in e.g. Area measurements.
>
> In fact, it is not very important for my results, but I would like to
> know where this inconsistency is coming from? If it is the bug or it
> is some kind of number conversion error?
>
> Here is the table you get by running macro on sample images
> <
https://urldefense.proofpoint.com/v2/url?u=https-3A__drive.google.com_open-3Fid-3D0BxY9MV1ofnZCdDljMGJheFE3ZWc&d=DQIDaQ&c=j5oPpO0eBH1iio48DtsedbOBGmuw5jHLjgvtN2r4ehE&r=oU_05LztNstAydlbm5L5GDu_vAdjXk3frDLx_CqKkuo&m=1956Dpgo0yCBsxu01cWYmVT7QnMxicxOqg9lu1WAIiM&s=9ikBU0SOzve1eOwtPgpYIHBZMgBjn52ojn7vzt_prek&e= >:
>
> Label pixelSize Area
> Mik437_Fe_dx0735.dcm 0.139999000 2620.913757974 Mik437_Fe_dx0735.tif
> 0.139999000 2620.913757974 Mik437_Fe_dx0735-reopen.tif 0.139999003
> 2620.913878054 Mik441_Fe_dx0751.dcm 0.100002000 1483.049660400
> Mik441_Fe_dx0751.tif 0.100002000 1483.049660400
> Mik441_Fe_dx0751-reopen.tif 0.100002000 1483.049660993
> Macro:
> image="Mik437_Fe_dx0735.dcm"; //"bad" image
> //image="Mik441_Fe_dx0751.dcm"; //"good" image run("Set
> Measurements...", "display redirect=None decimal=9");
> path=getDirectory("choose folder with example images");
> open(path+image); title=replace(getTitle(), ".dcm", ""); measure();
> saveAs("Tiff", path+title+".tif"); measure(); run("Revert"); //reopen
> last saved tif newTitle=title+"-reopen.tif"; rename(newTitle);
> measure(); close();
>
> function measure() {
> title=getTitle();
> getVoxelSize(gVwidth, height, depth, unit); getStatistics(Area);
> n=nResults; setResult("Label", n, title); setResult("pixelSize", n,
> gVwidth); setResult("Area", n, Area);
>
> ----------------------------------------
> I would appreciate any hints.
>
> Have a nice day.
> Schebique
>
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