OpenCV 3计算机视觉：Python语言实现（原书第2版）内容不全，代码错误纠正

• 关于第三章3.6节的错误

  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)
  
  

  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

• 3.10章节缺失代码

import cv2
import numpy as np

img = cv2.pyrDown(cv2.imread("hammer.jpg", cv2.IMREAD_UNCHANGED))

ret, thresh = cv2.threshold(cv2.cvtColor(img.copy(), cv2.COLOR_BGR2GRAY) , 127, 255, cv2.THRESH_BINARY)
black = cv2.cvtColor(np.zeros((img.shape[1], img.shape[0]), dtype=np.uint8), cv2.COLOR_GRAY2BGR)

image, contours, hier = cv2.findContours(thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

for cnt in contours:
  epsilon = 0.01 * cv2.arcLength(cnt,True)
  approx = cv2.approxPolyDP(cnt,epsilon,True)
  hull = cv2.convexHull(cnt)
  cv2.drawContours(black, [cnt], -1, (0, 255, 0), 2)
  cv2.drawContours(black, [approx], -1, (255, 255, 0), 2)
  cv2.drawContours(black, [hull], -1, (0, 0, 255), 2)

cv2.imshow("hull", black)
cv2.waitKey()
cv2.destroyAllWindows()