Python-OpenCV/Chapter 8.py at master · codemike513/Python-OpenCV · GitHub

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# CONTOURS/SHAPE DETECTION

import cv2
import numpy as np


def stackImages(scale, imgArray):
    rows = len(imgArray)
    cols = len(imgArray[0])
    rowsAvailable = isinstance(imgArray[0], list)
    width = imgArray[0][0].shape[1]
    height = imgArray[0][0].shape[0]
    if rowsAvailable:
        for x in range(0, rows):
            for y in range(0, cols):
                if imgArray[x][y].shape[:2] == imgArray[0][0].shape[:2]:
                    imgArray[x][y] = cv2.resize(
                        imgArray[x][y], (0, 0), None, scale, scale)
                else:
                    imgArray[x][y] = cv2.resize(
                        imgArray[x][y], (imgArray[0][0].shape[1], imgArray[0][0].shape[0]), None, scale, scale)
                if len(imgArray[x][y].shape) == 2:
                    imgArray[x][y] = cv2.cvtColor(
                        imgArray[x][y], cv2.COLOR_GRAY2BGR)
        imageBlank = np.zeros((height, width, 3), np.uint8)
        hor = [imageBlank]*rows
        hor_con = [imageBlank]*rows
        for x in range(0, rows):
            hor[x] = np.hstack(imgArray[x])
        ver = np.vstack(hor)
    else:
        for x in range(0, rows):
            if imgArray[x].shape[:2] == imgArray[0].shape[:2]:
                imgArray[x] = cv2.resize(
                    imgArray[x], (0, 0), None, scale, scale)
            else:
                imgArray[x] = cv2.resize(
                    imgArray[x], (imgArray[0].shape[1], imgArray[0].shape[0]), None, scale, scale)
            if len(imgArray[x].shape) == 2:
                imgArray[x] = cv2.cvtColor(imgArray[x], cv2.COLOR_GRAY2BGR)
        hor = np.hstack(imgArray)
        ver = hor
    return ver


def getContours(img):
    contours, hierarchy = cv2.findContours(
        img, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)
    for cnt in contours:
        area = cv2.contourArea(cnt)
        print("\nArea = " + str(area))
        if area > 500:
            cv2.drawContours(imgContour, cnt, -1, (255, 0, 0), 3)
            peri = cv2.arcLength(cnt, True)
            print("Perimeter = " + str(peri))
            approx = cv2.approxPolyDP(cnt, 0.02*peri, True)
            print("Number of Side = " + str(len(approx)))
            objCor = len(approx)
            x, y, w, h = cv2.boundingRect(approx)
            if objCor == 3:
                ObjectType = "Triangle"
            elif objCor == 4:
                aspRatio = w/float(h)
                if aspRatio > 0.95 and aspRatio < 1.05:
                    ObjectType = "Square"
                else:
                    ObjectType = "Rectangle"
            elif objCor > 4:
                ObjectType = "Circle"
            else:
                ObjectType = None

            cv2.rectangle(imgContour, (x, y), (x+w, y + h), (0, 255, 0), 2)
            cv2.putText(imgContour, ObjectType, (x+(w//2)-10, y +
                                                 (h//2)-10), cv2.FONT_HERSHEY_COMPLEX, 0.6, (0, 0, 0), 2)


path = 'Resources/shapes.png'
img = cv2.imread(path)
imgContour = img.copy()

imgGray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
imgBlur = cv2.GaussianBlur(imgGray, (7, 7), 1)
imgCanny = cv2.Canny(imgBlur, 50, 50)
imgBlank = np.zeros_like(img)
getContours(imgCanny)


imgStack = stackImages(0.7, ([img, imgGray, imgBlur], [
                       imgCanny, imgContour, imgBlank]))

cv2.imshow('Stacked Images', imgStack)
cv2.waitKey(0)