Re: problems converting to 8-bit image

Posted by Name Suppressed - 000002948 on Apr 10, 2006; 4:06pm
URL: http://imagej.273.s1.nabble.com/problems-converting-to-8-bit-image-tp3703137p3703138.html

Converting to RGB first took care of it.

Thanks,
Kathryn Barto


Gabriel Landini wrote:

>On Friday 07 April 2006 20:29, Name Suppressed - 000002948 wrote:
>> I have quite a few images of plant roots traced in blue and black
>> marker. I'm trying to do some fractal analysis and want to convert
>> these images to 8-bit grayscale. The images are currently 8-bit color.
>> I've tried using 'image->type->8-bit' and that works for some of my
>> images, but for others the entire image becomes black. I tried
>> thresholding first and that will convert the entire root system to
>> black, but when I try converting to 8-bit grayscale the entire image
>> still becomes black.  Is there anything I can do about this?
>
>The 8 bit colour images have a palette, that is why one cannot

threshold
>properly (the palette is not likely to be in brightness order).
>You can try to convert them to RGB first, and then to 8 bit grey.
>The colours in the RGB image will remain quantised, but converting to 8
bit
>grey may still be enough to be able to threshold them.
>Once in RGB mode you can also try the colour_threshold plugin at my
site.
>Cheers,
>
>G.
>