类型错误：“图像”对象不支持项目分配

我正在运行下面的模型，在拆分图像并尝试重新分配图像后，我收到错误消息说明。

    sample[:, :, 0] = 0
TypeError: 'Image' object does not support item assignment

我尝试了不同的方法来将图像分配回样本，但这没有帮助。任何帮助将不胜感激。非常感谢

这是我用来加载数据的代码：

import os

import numpy as np
import torch
from PIL import Image
from torch.utils.data import Dataset
from torchvision import transforms, utils
from torchvision.transforms import functional
#from torchvision.transforms import Grayscalei
import pandas as pd
import pdb
import cv2
from cv2 import imread
from cv2 import resize

class CellsDataset(Dataset):
    # a very simple dataset

    def __init__(self, root_dir, transform=None, return_filenames=False):
        self.root = root_dir
        self.transform = transform
        self.return_filenames = return_filenames
        self.files = [os.path.join(self.root,filename) for filename in os.listdir(self.root)]
        self.files = [path for path in self.files
                      if os.path.isfile(path) and os.path.splitext(path)[1]=='.png']

    def __len__(self):
        return len(self.files)

        path = self.files[idx]
        sample = Image.open(path)
        sample = np.asarray(sample, dtype=np.uint8)
        sample = cv2.resize(src=sample, dsize=(1024, 1024))
        sample = functional.to_grayscale(sample, num_output_channels=3)

        sample[:, :, 0] = 0
        sample[:, :, 1] = 0

        if self.transform:
            sample = self.transform(sample)

        if self.return_filenames:
            return sample, path
        else:
            return sample

    def duplicate_and_transform(self,transforms):
        currfilelen = self.__len__()
        
        for pind in range(0,currfilelen-1):
            path = self.files[pind]
            sample = Image.open(path)
            samplet = transforms(sample)
            # save the transformed images and save the associated counts:
            newpath = path[:-4]+'trans.png' #path[:-4] is the path without the .png extension.
            samplet.save(newpath,"PNG")
            metadata = pd.read_csv(os.path.join(self.root,'gt_red.csv'))
            metadata.set_index('filename',inplace=True)
            count = metadata['count'][os.path.split(path)[-1]]
            samplet.save(newpath,"PNG")
            f = open(self.root+'gt.csv','a')
            basepath = os.path.basename(path) # strip away the directory list and just get the filename
            f.write(basepath[:-4]+'trans.png,'+str(count)+'\n')
            # return the new file names and add to self.files.
            self.files.append(newpath)
            #pdb.set_trace()