Re: Threshold preview Display Inconsistencies

Posted by Gabriel Landini on Mar 04, 2015; 2:36pm
URL: http://imagej.273.s1.nabble.com/Threshold-preview-Display-Inconsistencies-tp5011866p5011871.html

On Wednesday 04 Mar 2015 12:40:11 Burri Olivier wrote:
> We are having a problem with the threshold display for 32 bit images.
>
> Example.
> An image with a wide range of values, we set the threshold to 1-Infinity,
> the whole image appears in red, but when we hit Apply and set "Background
> to NaN", the proper pixels are set to NaN on the image, making what the
> preview was showing inconsistent.

I think this might have to do with the way that 32bit images are handled when
applying the threshold methods (which expect a histogram).
The various thresholding methods of the Auto Threshold plugin which were later
ported into the built-in thresholder are for discrete values (i.e. 8 or 16 bit
images).

I seem to remember that Wayne implemented a way round to apply this to 32bit
images in IJ, so they get pre-binned into a range of values (not exactly sure)
I think it is 256 but cannot remember if it is fixed either.

Cheers

Gabriel

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