我們經常會使用contour或者自己圈出來的區(qū)域填上對應的值或者，所以經常會使用這樣兩個函數(shù)：fillPoly和fillConvexPoly，至于這兩個函數(shù)有什么區(qū)別呢？小伙伴從題目中就可以看出來了，一個是任意多邊形進行填充(有可能是非凸的)，一個是對凸多邊形進行填充。

兩個函數(shù)的使用方法和說明：

官方文檔：函數(shù)fillConvexPoly繪制一個填充的凸多邊形。 該函數(shù)比函數(shù)fillPoly快得多。 它不僅可以填充凸多邊形，而且可以填充任何不具有自相交的單調多邊形，即，其輪廓與每個水平線(掃描線)相交的多邊形最多兩次(盡管其最頂部和/或底部邊緣可能是 水平)。

def fillConvexPoly(img, points, color, lineType=None, shift=None): # real signature unknown; restored from __doc__

"""

fillConvexPoly(img, points, color[, lineType[, shift]]) -> img

. @brief Fills a convex polygon.

.

. The function cv::fillConvexPoly draws a filled convex polygon. This function is much faster than the

. function #fillPoly . It can fill not only convex polygons but any monotonic polygon without

. self-intersections, that is, a polygon whose contour intersects every horizontal line (scan line)

. twice at the most (though, its top-most and/or the bottom edge could be horizontal).

.

. @param img Image.

. @param points Polygon vertices.

. @param color Polygon color.

. @param lineType Type of the polygon boundaries. See #LineTypes

. @param shift Number of fractional bits in the vertex coordinates.

"""

pass

官方文檔：函數(shù)fillPoly填充由多個多邊形輪廓所界定的區(qū)域。 該功能可以填充復雜的區(qū)域，例如，帶有孔的區(qū)域，具有自相交的輪廓(部分輪廓)等等。

def fillPoly(img, pts, color, lineType=None, shift=None, offset=None): # real signature unknown; restored from __doc__

"""

fillPoly(img, pts, color[, lineType[, shift[, offset]]]) -> img

. @brief Fills the area bounded by one or more polygons.

.

. The function cv::fillPoly fills an area bounded by several polygonal contours. The function can fill

. complex areas, for example, areas with holes, contours with self-intersections (some of their

. parts), and so forth.

.

. @param img Image.

. @param pts Array of polygons where each polygon is represented as an array of points.

. @param color Polygon color.

. @param lineType Type of the polygon boundaries. See #LineTypes

. @param shift Number of fractional bits in the vertex coordinates.

. @param offset Optional offset of all points of the contours.

"""

pass

用起來也相當方便了，寫了個小例子

import cv2

img_star = cv2.imread("../test_imgs/star.jpeg")

img_star_gray = cv2.cvtColor(img_star, cv2.COLOR_BGR2GRAY)

kernel =cv2.getStructuringElement(cv2.MORPH_RECT,(5,5))

retval, dst = cv2.threshold(img_star_gray, 0, 255, cv2.THRESH_OTSU)

cv2.imshow("bin: ", dst)

cv2.waitKey(0)

contours, _ = cv2.findContours(dst, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

cv2.fillPoly(img_star, [contours[0]], (0,255,255))

#cv2.fillConvexPoly(img_star, contours[0], (0,255,255))

cv2.imshow("dst: ", img_star)

cv2.waitKey(0)

cv2.destroyAllWindows()

下載了一顆五角星，這個效果會比較明顯：

我們先進行二值化：

使用cv2.fillPoly進行填充：

使用cv2.fillConvexPoly進行填充：

這個例子應該相當明顯了(≧▽≦)/啦啦啦！

總結

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