Max and Min Grey values

[Christopher McFarlane]

Hi

I am an undergrad student doing some image analysis on some thin sections of some rocks.  I would like for someone to clarify what Max and Min gray values are.  If you need to threshold an image before you analyze the particles, which takes it to black and white, what Grey values are ImageJ measuring?  Does it preserve grey values?

I guess I am trying to get ImageJ to measure individual grains and get actual maximum and minimum area of the different particles.  How do I do this?

Thanks alot
Christopher

[Wayne Rasband]

> I am an undergrad student doing some image analysis on some thin
> sections of some rocks.  I would like for someone to clarify what Max
> and Min gray values are.  If you need to threshold an image before you
> analyze the particles, which takes it to black and white, what Grey
> values are ImageJ measuring?  Does it preserve grey values?

You do not need to convert an image to black and white to use the
particle analyzer. All you have to do is set the threshold levels using
the Image>Adjust>Threshold tool. Gray values are preserved.

-wayne