Re: RGB to binary problem

Posted by Albert Cardona on Jun 24, 2008; 6:02pm
URL: http://imagej.273.s1.nabble.com/RGB-to-binary-problem-tp3695771p3695772.html

> I have tried to change RGB images to binary by going to process -> binary ->
> make binary, but in this way I get a lot of background noise in many of the
> images.
>
> By chance I have done the process going through 32-bit gray scale (image ->
> type -> 32-bit) and than "make binary" and saw that it bypasses the
> background noise problem.
>
> Have anyone else encountered this phenomenon? Are there any comments?
>  

I suspect your RGB image goes to 8-bit color first (which is terrible
for any quantification, since pixel intensities no longer correlate to
color intensity), and then to binary.

RGB to 32 bit will do the right thing: create a luminance image and put
it into a float array.

You can see what RGB really is if you convert the RGB to HSB, and then
use the 'B' slice of the 3-slice stack (the Brightness channel) which is
essentially the grayscale version of your image (Hue and Saturation
containing the color information.)

Albert

--
Albert Cardona
http://www.mcdb.ucla.edu/Research/Hartenstein/acardona