how to Specifying the position of a color in the black and white color spectrum?

Hi dears.

I'm trying to collect data from moving lines in photos. For this purpose, the photos must be analyzed by MATLAB after applying certain filters (such as blurr and fill). These lines have black and white halos after applying the blur filter. The middle of these halos should be identified by MATLAB and the coordinates of these lines (the lines that are identified in the middle of the halos) should be recorded. Photo 1 is an example of a raw image taken from these lines, which is converted to Photo 2 after uses blur filter. Then something like the third image should be converted by MATLAB ( after transformation) and the coordinates of the lines should be recorded.

please guide me

Thank you!