opencv 11 trackbar adjust brightness

original image

increase brightness, trackbar value 75

decrease brightness, trackbar value 25

#main.py

import numpy as np

import cv2

cap = cv2.VideoCapture("assets/Santa Barbara.mp4")

brightness = 50

#create trackbar with white background

trackbars_img = np.uint8(np.full((50, 500, 3), 255))

cv2.imshow('trackbars', trackbars_img)

def brightness_change(x):

    global brightness

    brightness = x

#create trackbar (trackbar name, window name, default value, max value, onChange)

cv2.createTrackbar('Brightness', 'trackbars', 50, 100, brightness_change)

while True:

    ret, frame = cap.read()

    width = int(cap.get(3))

    height = int(cap.get(4))

    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

    h, s, v = cv2.split(hsv)

    brightness_adjuster = int((brightness - 50) / 50 * 255)

    #print(brightness_adjuster)

    v_int16 = np.int16(v) + brightness_adjuster

    v_int16[v_int16 > 255] = 255

    v_int16[v_int16 < 0] = 0

    #print(v_int16)

    v = np.uint8(v_int16)

    #print(v)

    final_hsv = cv2.merge((h, s, v))

    image = cv2.cvtColor(final_hsv, cv2.COLOR_HSV2BGR)

    cv2.imshow('frame', image)

    if cv2.waitKey(1) == ord('q'):

        break

    if cv2.waitKey(1) == ord('p'):

        # wait until any key is pressed

        cv2.waitKey(-1)

cap.release()

cv2.destroyAllWindows()

reference:

https://www.youtube.com/watch?v=fM6ff3VEviI&list=PLS1QulWo1RIa7D1O6skqDQ-JZ1GGHKK-K&index=13

adjust brightness

https://stackoverflow.com/questions/32609098/how-to-fast-change-image-brightness-with-python-opencv

np.full

https://stackoverflow.com/questions/14112235/how-do-i-create-an-array-whose-elements-are-all-equal-to-a-specified-value