How to use specific position in binary image

Hello, i have bw image with some objects on it, i have detected an object and give him a number,

Now I want to track it from frame to frame,so how can i check if my object at a new frame appears nearby his old location (to give him the same number)? I know a coordinates of my object at present frame and i want to check if i have some objects at next frame around this coordinates. I want to check my image only in this area:

-Top, Left corner: (cog_x - 100, cog_y - 100)

-Top, Right corner: (cog_x + 100, cog_y - 100)

-Bottom, Left corner: (cog_x - 100, cog_y + 100)

-Bottom, Right corner: (cog_x + 100, cog_y + 100)

How can i do it in matlab? Sorry for my English

Answer 1

[Image Analyst]

You ask "how can i check if my object at a new frame appears nearby his old location (to give him the same number)? " Answer - use the Pythagorean Theorem to calculate the distance.

[Felix]

No, I mean, how can I approach only to specific place on binary image because I want to check if I have some objects on this area. Thnx