Re: Image Thresholding for Binary workflow

Posted by Michael Schmid on
URL: http://imagej.273.s1.nabble.com/Image-Thresholding-for-Binary-workflow-tp5007850p5007873.html

Hi Rainer,

> Process > Binary > Make Binary
> sometimes caused plausible black/white dominance switches.

If you have this problem, it is most likely caused by different settings of 'Black Background' in Process>Binary>Options.  You should also check whether the image has an inverted LUT.

> I tried ..
> setMinAndMax(173, 173);
> .. but this does no clamping like I thought it might..

The setMinAndMax changes only the display, not the image data. For 8-bit images, this is done via the LUT, so you can apply the LUT afterwards, and the image will be converted to 0 (values less or equal 173) and 255 (values higher than 173).  The mapping will be independent on LUT and Black background settings:

setMinAndMax(173, 173);
run("Apply LUT");


Michael
________________________________________________________________
On May 22, 2014, at 11:23, Rainer M. Engel wrote:

> Hello together,
>
> I'm looking for way to threshold an image and in the same process making
> it binary.
>
> Process > Binary > Make Binary
> sometimes caused plausible black/white dominance switches.
>
> Process > Math > Macro
> works better for my purposes (i.e.| if (v<=25) v=0; else v=255)
>
> The later Expression is very slow compared even to an Gaussian Blur or
> similar. Are there other, hopefully faster ways (for high resolution) to
> threshold and make binary (8bit)?
>
> I tried ..
> setMinAndMax(173, 173);
> .. but this does no clamping like I thought it might..
>
> Any help is much appreciated.
>
> Best regards,
> Rainer

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