'**SUMMARY**
Returns the darkest/minimum pixel value in the
grayscale image. This method can also return the
locations of pixels with this value.
**PARAMETERS**
* *locations* - If true return the location of pixels
that have this value.
**RETURNS**
The minimum value and optionally the list of points as
a list of (x,y) tuples.
**EXAMPLE**
>>> img = Image("lenna")
>>> max = img.maxValue()
>>> min, pts = img.minValue(locations=True)
>>> img2 = img.stretch(min,max)'

def minValue(self, locations=False):

    if locations:
        val = np.min(self.getGrayNumpy())
        (x, y) = np.where((self.getGrayNumpy() == val))
        locs = zip(x.tolist(), y.tolist())
        return (int(val), locs)
    else:
        val = np.min(self.getGrayNumpy())
        return int(val)
