PYTHON-OPENCV Boundingrect Use note

The rectangular border (bounding Rectangle) is said to wrap the found shape with a minimum rectangle. There is also a rectangle with a rotation, the area will be smaller, the effect see

On the Code

First introduce the next Cv2.boundingrect (IMG) function

This function is very simple, IMG is a binary graph, that is, its parameters;

Returns four values, respectively, x,y,w,h;

X, y is the coordinates of the top left of the matrix, W,h is the width and height of the matrix

Then usecv2.rectangle(img, (x,y), (x+w,y+h), (0,255,0), 2)画出矩行

参数解释

第一个参数：img是原图

第二个参数：（x，y）是矩阵的左上点坐标

第三个参数：（x+w，y+h）是矩阵的右下点坐标

第四个参数：（0,255,0）是画线对应的rgb颜色

第五个参数：2是所画的线的宽度


# with Green (0,255,0) to draw the smallest rectangle frame x, y, W, H=Cv2.boundingrect (CNT) Cv2.rectangle (IMG, (x, y), (x+w, Y+h), (0,255,0),2# in red indicates a rectangular frame with a rotation angle rect=cv2.minarearect (CNT) box=cv2.cv.BoxPoints (rect) box=np.int0 (Box) cv2.drawcontours (IMG, [box],0, (0,0,255),2) Cv2.imwrite ('Contours.png', IMG)

However, if used in Python, there is no vector or mat as input to the Boundingrect, the following error will appear:

    X, Y, W, h = cv2.boundingrect (landmarks) typeerror:points is not a numpy array, neither a scalar

The above landmark as input is a list,
Solution:
Therefore, we need to introduce numpy to his strong turn, the specific operation is as follows:

Import as  = cv2.boundingrect (np.array (landmarks))  + W, y + h), (0  25502)

This allows you to turn the list into an array.

PYTHON-OPENCV Boundingrect Use note