Re: Replace NaN in 32-bit images with 0

Posted by Jeffrey B. Woodward on Mar 23, 2011; 7:01pm
URL: http://imagej.273.s1.nabble.com/Replace-NaN-in-32-bit-images-with-0-tp3685307p3685309.html

The best (most readable) option is to use Double.isNaN(v); however, if
you are looking for a "clever" inequality that is "more correct" and
simpler than the one suggested by Michael Schmid, you can simply test
whether or not v == v...which is only false for NaN. In summary:

Best option:
     if (Double.isNaN(v)) v = 0;

"Clever"/obscure option:
     if (v != v) v = 0;

-Woody


On 3/23/2011 1:40 PM, Michael Schmid wrote:

> Hi anonymous,
>
> this may look stupid, but it works at least with the NaN created by
> division by zero:
> Enter in the Process>Math>Macro
>     if (!(v<1) && !(v>0)) v=0;
>
> A NaN value fulfills no inequality; all 'true' numbers are either <1
> or >0 or both.
> Of course, a macro function 'isNaN(value)' would be nice to have...
>
> Michael
> ________________________________________________________________
>
> On 23 Mar 2011, at 18:03, mjlm wrote:
>
>> Hi there,
>>
>> Is there a simple way to "reset" all pixels with the value "NaN" to a
>> specified numeric value, e.g. 0?
>>
>> I couldn't find a way to do this properly in ImageJ...one ugly
>> workaround I
>> came up with is to save the image as text and then simply find &
>> replace all
>> occurences of NaN, but that's not a feasible option for large
>> stacks...there
>> MUST be a better way.
>>
>> Thanks!

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