有没有更快的方法可以在python中遍历图像

Question

程序是关于去除渐变背景色的 目前，尺寸为420X560的单个图像大约需要20秒 代码是

from colormath.color_objects import sRGBColor, LabColor
from colormath.color_conversions import convert_color
from colormath.color_diff import delta_e_cie2000
import matplotlib.pyplot as plt  
from matplotlib.colors import LogNorm 
import numpy as np
import os
import cv2
  
def backgroundRemovel(url):    
    img = cv2.imread(url)    
    img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
    plt.imshow(img)
    plt.title('original Image')
    plt.show() 
    color=img[0,0]
    firstPixelRGB = sRGBColor(color[0], color[1], color[2], is_upscaled=True);
    firstPixelLab = convert_color(firstPixelRGB, LabColor);
    t=img.shape
    x_dim=t[0]
    y_dim=t[1]
    for i in range(x_dim):
          for j in range(y_dim):
            rgbCurPixel=img[i,j]
            curPixelRGB=sRGBColor(rgbCurPixel[0], rgbCurPixel[1], rgbCurPixel[2], is_upscaled=True);
            curPixelLab=convert_color(curPixelRGB, LabColor);
            delta_e = delta_e_cie2000(firstPixelLab, curPixelLab);
            #print("difference is "+str(delta_e))
            if delta_e<15: 
                img[i, j] = (0, 0, 0)
   
    return img  


fnmae="image.jpeg"
open_cv_image = backgroundRemovel(fname)
plt.imshow(open_cv_image)
plt.title('Background Removed Image')
plt.show() 

输入图像： 期望的：

如果有更好的方法来去除图像的渐变背景，请共享