What do we call the areas with "1" in a binary image I am looking for possible professional terms. In a binary (1 or 0) image, normally, the areas with "1"s are where the information is. I wonder if there is any professional name for it in image processing. Thank you!
This problem born when you use pixel intensity as physical mass, for example to calculate mass center or inertia moments, in this case the background should be 0 and object should be 1.

Btw your question is not clear because in a binary image {0,1} have the same information content and generally there are not difference.

There is not a name for 1 pixel and 0 pixel, often in common convention 1 is white and 0 is black, but it's not a general rule. Maybe you can call 1 high value pixel and 0 low value pixel but I think that are not common names and they can make confusion in some contexts.