It turns out that since an image can have any color at any point that I needed to check around the area of the crop box. I am now looking at the starting 4 corners and changing the color based on the majority color. Also I found that white is best overall for the box outline so I am testing for the brightness at the 4 corners. If it is very bright then I use black. As Dragan pointed out, using the contrasting color does not work if you have a mid range color. It would be wonderful if I could change the color at each point on the shape border but I fear that is beyond the capabilities of VFP, at least without drawing and re-drawing every point individually.

Thanks to everyone for the suggestions.