adjust the V value of an HSV image to controle the brightness on a data set

Question

I Am trying to homogenise a set of images to have the same brightness so I transformed my images into HSV images and I modified the value of the V channel , i used the avrege value of each 3 successive images and then replaced the V value of a specific image with that value, but for some reason the images where too dark. is there a way to homogenise the images using the V channel and how could I fix the images brightness problem.

here is the code that i used :

def imgChange(imgPath):
    img = cv2.imread(imgPath)
    hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
    h, s, v= cv2.split(hsv)
    return v



def changeV(imgPath, vNew): 
    print(imgPath)
    img = cv2.imread(imgPath)
    hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
    h, s, v= cv2.split(hsv)

    hsv = cv2.merge((h, s, vNew))

    img = cv2.cvtColor(hsv, cv2.COLOR_HSV2BGR)
    cv2.imwrite(imgPath, img)


V = []
a = []
for i, image in enumerate(os.listdir(pathDossier)) :
    if image.endswith(".jpg"):
        pathimg = pathDossier + "\\" + image
        a = imgChange(pathimg)
        V.append(imgChange(pathimg))
          
for i, image in enumerate(os.listdir(pathDossier)) :
    
    if image.endswith(".jpg"):
        if i < len(V)-3 :
            listdata = (sum(V[i:i+3]))//3
            vNew = np.array(listdata, dtype = np.uint8)
            pathimg = pathDossier + "\\" + image
            changeV(pathimg, vNew)