Re: ImageJ "mean" vs Photoshop "mean"?

Posted by Michael Schmid on Nov 30, 2020; 9:21am
URL: http://imagej.273.s1.nabble.com/ImageJ-mean-vs-Photoshop-mean-tp5024242p5024249.html

Hi David,

if your image file has tiff format, it could have some nonlinear
transfer function (e.g. a color calibration function) that is taken into
account by photoshop, not by ImageJ. ImageJ is usually used for images
from scientific cameras that have linear transfer functions, so it does
not take the tiff tags for nonlinear transfer functions into account
(tag decimal 301 = hex 012D "TransferFunction", 50940 = hex C6FC
"ProfileToneCurve")

If you switch on debug mode (under Edit>Options>Misc), you will see
whether such a tiff tag is present. As many others have said already, it
would have been easier with a sample file.

Michael
________________________________________________________________
On 28.11.20 19:26, David Palermo wrote:
> I am using my scanner as a densitometer and I am measuring gray patches from a step-wedge in both Photoshop and ImageJ. The mean values are different between each program. Why is that? ImageJ's mean is 41726 and Photoshop's mean of the same patch from the same file is 20861.
>
> Thank you!
>
> David

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