我在文件夾中有5張圖片。我想把所有這些圖像都轉(zhuǎn)換為灰度。import globcolorIm = []for filename in glob.glob('/content/drive/My Drive/Colab Notebooks/Asplab/Cifar/*.png'):  print(filename)  img = Image.open(filename)  colorIm.append(img)  greyIm=colorIm.convert('L')屬性錯(cuò)誤：“列表”對(duì)象沒(méi)有屬性“轉(zhuǎn)換”