What do I do in this summer~

Due to my group of Lab joins a Machine Vision Contest about calculation hardness of indentation~ So we have to find four vertex of the indentation automatically by image processing technology ! It's a difficult problem because +-1 pixel is only accepted by sponsor, we face a lot of diamonds on monitor every day for finding four vertex of the indentation likes as a diamond ~ Segmentation background and foreground is key processing in our problem, missing correct points from segmentation will effect the accurate . We try a lot of methods to detect the vertex in image ~ I use least-square method to get the line form a set of data points that are edges of diamond and calculate the intersection of two line ,so I can determine the vertex coordinates of the indentation~