'**SUMMARY**
Region select is similar to crop, but instead of taking a position and width
and height values it simply takes two points on the image and returns the selected
region. This is very helpful for creating interactive scripts that require
the user to select a region.
**PARAMETERS**
* *x1* - Int - Point one x coordinate.
* *y1* - Int  - Point one y coordinate.
* *x2* - Int  - Point two x coordinate.
* *y2* - Int  - Point two y coordinate.
**RETURNS**
A cropped SimpleCV Image.
**EXAMPLE**
>>> img = Image("lenna")
>>> subreg = img.regionSelect(10,10,100,100) # often this comes from a mouse click
>>> subreg.show()
**SEE ALSO**
:py:meth:`crop`'

def regionSelect(self, x1, y1, x2, y2):

    w = abs((x1 - x2))
    h = abs((y1 - y2))
    retVal = None
    if ((w <= 0) or (h <= 0) or (w > self.width) or (h > self.height)):
        logger.warning('regionSelect:    the    given    values    will    not    fit    in    the    image    or    are    too    small.')
    else:
        xf = x2
        if (x1 < x2):
            xf = x1
        yf = y2
        if (y1 < y2):
            yf = y1
        retVal = self.crop(xf, yf, w, h)
    return retVal
