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Re: Magnification

Posted by fmonson on Mar 25, 2013; 6:43pm
URL: http://imagej.273.s1.nabble.com/Magnification-tp5002384p5002398.html

Now, the simple answer.
When you crop an image you do not change its magnification - if that is knowable - UNLESS you resize what is left.  Changing the resolution will not change the 'magnification' UNLESS the size of the image is altered in the process.  

The final magnification of 'John' may be different but all changes to the image of 'John' are relative.  John is not any bigger than he was when the image was captured, and unless you know the dimension of some object in the image that is left, the magnification will not be calculable.  

Processing of the type you have performed is usually applied to improve the image.  If you still have the original image, you can determine the 'new magnification' by comparing the dimensions of corresponding objects in the original and final images.

Cheers, again,

Fred

Frederick C. Monson, PhD
Technical Director
Center for Microanalysis and Imaging, Research and Training (CMIRT)
West Chester University of Pennsylvania
Schmucker Science South - Room SSS-024
MailDrop:  Geology-Astronomy
750 South Church Street
West Chester, PA, 19383
610-738-0437
[hidden email]

HomePage:  http://cmirt.wcupa.edu (with link to instrument Scheduler)


-----Original Message-----
From: ImageJ Interest Group [mailto:[hidden email]] On Behalf Of esther31
Sent: Monday, March 25, 2013 12:47 PM
To: [hidden email]
Subject: Magnification

How do I know what magnification do I have?
I scanned my picture, the whole image size is 2464x3432 pixels. I cropped it to remove excess background to 1260x1260 pixels. Then I selected a 296x296 pixels and duplicate that to open in a separate window.

I need to know the magnification of that window. Does anybody know how to measure it?

Thanks!



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