Posted by
Gabriel Landini on
Mar 25, 2013; 7:31pm
URL: http://imagej.273.s1.nabble.com/Magnification-tp5002384p5002400.html
Here is my take on this:
Magnification means how much bigger or smaller the image is compared to the
original object. That is OK if you only use a microscope, but gets confusing
when you use images (i.e. how bigger/smaller will they be shown/printed?).
As Stoyan suggested, scan a ruler and measure how big a pixel is (you can do a
spatial calibration within IJ with the scan of the ruler). Because you rarely
know at which size the image will eventually be shown or printed, the best
approach (others might differ) is to either:
a) add a calibration bar (there is a command for this) or
b) just give the size in calibrated units of the width of the photo and report
this in the legend (i.e. field width 54cm)
The advantage of a) is that you do not have to remember this size and still
have the bar if you choose to crop it or resize. The advantage of b) is that
you do not change the pixels of the image by drawing the bar. I think that you
can add the bar as an overlay, but not sure all programs might be able to show
it.
I always quote pixel size as well, because in images given in calibrated
units, you can't easily tell the resolution (amount of detail) of the image.
But that is a different story.
Hope it helps
Gabriel
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