Posted by
Glen MacDonald-2 on
Feb 11, 2014; 1:17am
URL: http://imagej.273.s1.nabble.com/calculate-magnification-tp5006474p5006481.html
Open the image in Fiji and disable any spatial calibration (Analyze>Set Scale). draw a line across the 3 mm object with the straight line tool. You have 2 options- Measure the length (Analyze>Set Measurements>Perimeter [gives length on straight lines]) and divide # pixels/3 mm for pixels/mm; or go back to Set Scale and enter the known distance. This can be set for future images through Image> Properies…
Note that saving files as jpeg or tiff will often throw away the spatial calibration. Another option for measuring the diameter is to download the FWHM macro.
For more info, Help>ImageJ Documentation
Glen
Glen MacDonald
Core for Communication Research
Virginia Merrill Bloedel Hearing Research Center
Cellular Morphology Core
Center on Human Development and Disability
Box 357923
University of Washington
Seattle, WA 98195-7923 USA
(206) 616-4156
[hidden email]
On Feb 10, 2014, at 8:39 AM, xlancelot <
[hidden email]> wrote:
> Hi everybody,
>
> i would like to calculate the magnification of my image
>
> i took an image of a mark with actual size 3 mm using my webcam
>
> image resolution is 1600x1200 and the webcam is using 2 MP cmos sensor
>
> now how can i calculate the magnification between the mark real size and the
> mark shown form the image ?
>
> sorry for my bad english
>
> thank you
>
>
>
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