How to binarize an image by keeping the NaNs and using a threshold?

Hello,

I am a novice with Matlab. I have a 3D array with NaNs, corresponding to the outside of an porous object. I would like binarize this image (units 8) with a treshold equal to 15. To do it, I used:

Bimg = imgd3 >15;

The binarization works but when I do it, the NaNs become 0 value. I want to keep the NaNs because they correspond to the outside of my object.

Any idea ?

Thank :)

Answer 1

[Matt J]

nanmap=isnan(imgd3);
Bimg = imgd3 >15;
Bimg(nanmap)=nan;

[Lequette Kevin]

Thank Matt J for your answer. However, when I used this code, there is a error message:

NaN's cannot be converted to logicals.

But if I do this:

nanmap=isnan(imgd3);
Bimg = double(imgd3 >15);
Bimg(nanmap)=nan;

It works ^^ Thank for your help!

[Walter Roberson]

By definition, binary only has 2 values, not three. Not 0, 1, or nan.

You should be storing your mask in a different array.