使用双线性插值的错误图像

import numpy as np
from PIL import Image

def bilinear_interpolation(img, scale_factor):
    width, height = img.size
    new_width = int(width * scale_factor)
    new_height = int(height * scale_factor)
    
    new_img = Image.new('RGB', (new_width, new_height))
    
    for y in range(new_height):
        for x in range(new_width):
            src_x = x / scale_factor
            src_y = y / scale_factor
            
            x1 = int(src_x)
            y1 = int(src_y)
            x2 = min(x1 + 1, width - 1)
            y2 = min(y1 + 1, height - 1)
            
            wa = (x2 - src_x) * (y2 - src_y)
            wb = (x2 - src_x) * (src_y - y1)
            wc = (src_x - x1) * (y2 - src_y)
            wd = (src_x - x1) * (src_y - y1)
            
            color_a = np.array(img.getpixel((x1, y1)))
            color_b = np.array(img.getpixel((x1, y2)))
            color_c = np.array(img.getpixel((x2, y1)))
            color_d = np.array(img.getpixel((x2, y2)))
            
            new_color = (wa * color_a + wb * color_b + wc * color_c + wd * color_d).astype(int)
            new_img.putpixel((x, y), tuple(new_color))
    
    return new_img

# 示例使用
img = Image.open('input.jpg')
scaled_img = bilinear_interpolation(img, 2.0)
scaled_img.save('output.jpg')