How to filter similar objects with same brightness value?

I have a binary image. Image contains bridge and ships both in bright while water is in black. I am trying to filter out bridge based on brightness threshold, but its not working. Anyone has any idea how to just filter out the bridge by keeping the other objects in the image?

Answer 1

[Image Analyst]

Perhaps by it's vertical location in the scene. Wouldn't the bridge be the highest thing? Or perhaps by the shape (aspect ratio) or size? Or perhaps by it's location if it's always in the same place because your camera is fixed on the shore. We can't really tell because you forgot to attach the binary image and grayscale or color image. Attach two sets of them so we can see what changes between the two smapshots.

[Hashir Tanveer]

It is actually a SAR(synthetic aperture radar), i have more than 100 images like this with bridge at the same position. I don't want to mask out the bridge as i want to make a universal solution. Yes, bridge and ships in the water have the same type of brightness. i want to filter out the bright point except the ones inside the river i.e ships. The image is attched below.

[Image Analyst]

My first image analysis project ever was working with inverse synthetic aperture radar back in 1980 (40 years ago) in San Diego. After reconstruction of the image, we had to identify different types of aircraft and watercraft from their shapes.

I'd start with hough or houghlines().

I can't give you a full solution because this is so difficult that it can't be done in just 5 or 10 minutes. Good luck though.