Filling specific holes in an image without changing edges

I tried doing a pixel wise hole filling operation that is if its surrounded by pixels whose sum exceeds a certain number, fill it. However, this seems to thicken edges as expected. Is there any way I can fill these small holes in the image without changing edge dimensions?

Thanks

[Catalytic]

However, this seems to thicken edges as expected.

No idea what you're talking about. Where is the demonstration of this?

Answer 1

[Matt J]

k=[1 1 1; 1 0 1; 1 1 1];

mask=conv2(YourImage,k,'same')>threshold;

YourImage=regionfill(YourImage,mask);