'**SUMMARY**
Get the ROI as a list of tuples of the ROI\'s top left
corner and bottom right corner. These coordinates are in unit
length values with respect to the source image.
**RETURNS**
A list of the form [(x,y),(x,y)]
**EXAMPLE**
>>> roi = ROI(10,10,100,100,img)
>>> roi.translate(30,30)
>>> print roi.toUnitTLAndBR()'

def toUnitTLAndBR(self):

    if (self.image is None):
        return None
    srcw = float(self.image.width)
    srch = float(self.image.height)
    (x, y, w, h) = self.toXYWH()
    nx = 0
    ny = 0
    nw = (w / srcw)
    nh = (h / srch)
    if (x != 0):
        nx = (x / srcw)
    if (y != 0):
        ny = (y / srch)
    return [(nx, ny), ((nx + nw), (ny + nh))]
