opencv3计算机视觉Python语言实现（原书第二版）第三章3.6节缺少BGRPortraCurveFilter()函数

3.6节中的对cameo.py的修改中，突然出现了filters.BGRPortraCurveFilter()让人措手不及。。。前面并没有写这个函数，后面也没有，查看原书英文版发现原书就是这样，坑啊，然后找来第一版，终于把坑补上了，废话不说，贴代码：

先把utils.py改为：

import cv2,numpy,scipy.interpolate

def createCurveFunc(points):
    """Return a function derived from control points."""
    if points is None:
        return None
    num_points = len(points)
    if num_points < 2:
        return None
    xs, ys = zip(*points)
    if num_points < 4:
        kind = 'linear'
        # 'quadratic' is not implemented.
    else:
        kind = 'cubic'
    return scipy.interpolate.interp1d(xs, ys, kind,bounds_error = False)


def createLookupArray(func, length = 256):
    """Return a lookup for whole-number inputs to a function. The lookup values are clamped to [0, length - 1]."""
    if func is None:
        return None
    lookup_array = numpy.empty(length)
    i = 0
    while i < length:
        func_i = func(i)
        lookup_array[i] = min(max(0, func_i), length - 1)
        i += 1
    return lookup_array

def applyLookupArray(lookup_array, src, dst):
    """Map a source to a destination using a lookup."""
    if lookup_array is None:
        return
    dst[:] = lookup_array[src]


def createCompositeFunc(func0, func1):
    """Return a composite of two functions."""
    if func0 is None:
        return func1
    if func1 is None:
        return func0
    return lambda x: func0(func1(x))


def createFlatView(array):
    """Return a 1D view of an array of any dimensionality."""
    flat_view = array.view()
    flat_view.shape = array.size
    return flat_view


然后，再在filters.py中加入三个类：
class BGRFuncFilter(object):

    def __init__(self, vFunc = None, bFunc = None, gFunc = None, rFunc = None,dtype = numpy.uint8) :

        length = numpy.iinfo(dtype).max + 1
        self._bLookupArray = utils.createLookupArray(utils.createCompositeFunc(bFunc, vFunc), length)
        self._gLookupArray = utils.createLookupArray(utils.createCompositeFunc(gFunc, vFunc), length)
        self._rLookupArray = utils.createLookupArray(utils.createCompositeFunc(rFunc, vFunc), length)

    def apply(self, src, dst) :

        """Apply the filter with a BGR source/destination."""
        b, g, r = cv2.split(src)
        utils.applyLookupArray(self._bLookupArray, b, b)
        utils.applyLookupArray(self._gLookupArray, g, g)
        utils.applyLookupArray(self._rLookupArray, r, r)
        cv2.merge([ b, g, r ], dst)



class BGRCurveFilter(BGRFuncFilter):

    def __init__(self, vPoints = None, bPoints = None,gPoints = None, rPoints = None, dtype = numpy.uint8):
        BGRFuncFilter.__init__(self, utils.createCurveFunc(vPoints), utils.createCurveFunc(bPoints), utils.createCurveFunc(gPoints), utils.createCurveFunc(rPoints), dtype)



class BGRPortraCurveFilter(BGRCurveFilter):
    def __init__(self, dtype = numpy.uint8):
        BGRCurveFilter.__init__(
            self,
            vPoints = [ (0, 0), (23, 20), (157, 173), (255, 255) ],
            bPoints = [ (0, 0), (41, 46), (231, 228), (255, 255) ],
            gPoints = [ (0, 0), (52, 47), (189, 196), (255, 255) ],
            rPoints = [ (0, 0), (69, 69), (213, 218), (255, 255) ],
            dtype = dtype)


这样，运行修改后的cameo.py就不会报错了