mainly the phrase "where you want to find the object" -- are we searching for an actual object?  I thought it's just an objective image, i.e. a target image?  But if there is an actual object involved it should be made clear what you're doing.

Below, the sentence should not start with "Backprojected" but "The backprojected".  "Higher" -> "A higher value".  "So thresholding" -> "So, thresholding".  "So for best" -> "For best".