Re: How to convert pixels into squaremicrometer

Posted by Gabriel Landini on May 03, 2007; 4:01pm
URL: http://imagej.273.s1.nabble.com/How-to-convert-pixels-into-squaremicrometer-tp3699617p3699620.html

On Thursday 03 May 2007 14:49:30 Volker Bäcker wrote:
> if you know the size of one ccd-element (from the description of the
> camera) you can calculate the pixel size.
>
> pixel size = size of one ccd-element / magnification

Remember to take into account for the magnification, any intermediate optics
in the extension tube that connects the camera and microscope (mine, for
example has a x0.5 lens in it).

It may be easier to measure a known distance of -let's say- micrometer
markings under the microscope and calculate the number of pixels, then divide
the real distance (in micromtres, etc) by the number of pixels and you will
have the pixel size. Then you put that value in the "set scale" dialog as
mentioned earlier.
However, this does not give you the resolving power of your setup. Many
objectives have less resolution than the pixel size you claculated. You
should consult the microscope manual for these values.

Many cameras sold for microscopy have smaller pixels than the resolving power
of the microscope objectives themselves, so caveat emptor!

Cheers,

Gabriel