Why NaN area is involved in segmented image?

I am using water-shed segmentation to segment objects (porous). But areas with NaN value set by codes, is still shown in segmented image (highlighted in color with other objects). Can anyone give me a clue? Thank you.

[Image Analyst]

No. No image and no code mean no answer.

[Tian Tian]

Thanks for reminding. Below is the code to convert to NaN value. for coloum = 1:width for row =1:height if (I(row,coloum)==0 | I(row,coloum)< 25) I(row,coloum)= nan; end end end In segmentation, I didn't mention any NaN value (only imopen, imclose, then segment).

Answer 1

[Tian Tian]

I used below to convert to NaN: for coloum = 1:width for row =1:height if (I(row,coloum)==0 | I(row,coloum)< 25) I(row,coloum)= nan; end end end