import cv2
import numpy as np
import matplotlib as plt
from matplotlib import pyplot as plt

cap = cv2.VideoCapture(1)

while True:
    F_num,O_frame =cap.read()
    frame = O_frame.copy()
    mask_corner1 = np.array([300,130])
    mask_corner2 = np.array([330,160])
    frame = cv2.rectangle(frame,tuple(mask_corner1),tuple(mask_corner2), (255,0,0),2)
    mask = np.zeros(frame.shape[:2],np.uint8)
    mask[130:160,300:330]=255
    # mask[int(mask_corner1[1]):int(mask_corner2[1]), int(mask_corner1[0]):int(mask_corner1[0])]=255
    masked_img = cv2.bitwise_and(O_frame,frame,mask=mask)
    cv2.imshow("mask",masked_img)
    color = ('b', 'g', 'r')
    for i, col in enumerate(color):
        # histr = cv2.calcHist([frame], [i], None, [256], [0, 256])
        hist_mask = cv2.calcHist([frame], [i], mask, [256], [0, 256])
        plt.plot(hist_mask, color=col)
        plt.xlim([0, 256])
    plt.draw()
    plt.pause(0.0001)
    plt.clf()

    cv2.imshow("Frame",frame)
    key = cv2.waitKey(1)
    if key== 27:
        break