This is a faster resizer that also applies an watermark image using opencv

opencv resizer_watermark.py

import cv2, os





watermark = cv2.imread(os.path.join("watermark.jpg"))
h_wtmk, w_wtmk = watermark.shape[:2]

def resize(inpath: str, outpath: str, size: tuple = (768, 512), inter: int = cv2.INTER_AREA) -> None:
    for infile in os.listdir(inpath):
        try:
            path = os.path.join(inpath, infile)
            #checking for folders
            if os.path.isdir(path):
                continue

            dim = None
            img = cv2.imread(path)
            img = img.copy()

            h_img, w_img = img.shape[:2]





            #adding watermark
            #calculating coordiantes of center
            center_y = h_img // 2
            center_x = w_img // 2

            #calculating from top, bottom, right and left
            top_y = center_y - h_wtmk // 2
            left_x = center_x - w_wtmk // 2
            bottom_y = top_y + h_wtmk
            right_x = left_x + w_wtmk

            destination = img[top_y: bottom_y, left_x: right_x]
            try:

                result = cv2.addWeighted(destination, 1, watermark, 0.5, 0)
                img[top_y: bottom_y, left_x: right_x] = result
            except cv2.error:
                print(f"Could not watermark: {infile}... Probably because the image is smaller than the watermark.")
                return



            if all(sizes == None for sizes in size):
                return

            if size[0] == None:
                r = size[1] / w_img
                dim = (int(w_img * r), size[1])
            
            else:
                r = size[0] / w_img
                dim = (size[0], int(h_img * r))
            
            resized = cv2.resize(img, dim, interpolation = inter)




            #saving
            cv2.imwrite(os.path.join(outpath, infile), resized)
            print("Resized and Watermarked:", infile)
        except IOError:
            print("Cannot neither resized nor watermark:", infile)