Re: Threshold

Posted by Wayne Rasband on Aug 26, 2005; 5:12pm
URL: http://imagej.273.s1.nabble.com/Threshold-tp3704976p3704977.html

> I am having difficulty creating binary images using the
> Threshold  that is called from Image-Adjust.   I want to
> generate a binary where  the feature of interest is gray 255
> and the remainder is 0. I used  the picker to set the gray
> value to 255 and use the scroll bars to  set upper and lower
> bounds.  Interestingly, I still see low count  noise even
> after the lower bound is set well above the noise gray 
> levels.  Next, when attempting to create the binary, a
> window  detailing options "Apply LUT' appears where I
> de-select the option  for black foreground, white
> background.  The resulting window is a  uniform level (62 in
> todays attempt) using the red option; using the  black and
> white option in another attempt results in a uniformly gray 
> image, again at level 62.  Another attempt using the
> Black-White  option and picker set to 255 resulted in the
> entire image being set  to 255.  I am using ImageJ 1.34S on
> a G5.

The easiest way to do this is to check "Black foreground, white
background" in the "Apply LUT" dialog and then press shift-i
(Edit>Invert).

-wayne