So, I found custom Dataset, that could be good for me.
But in case of my task and using Colab, it’s better for me to increase amount of images in the folders of classes.
I just use ImageFolder to create validation ImageFolder, then I activate function to copy missing pictures (because of it’s veeeeeery custom I wouldn’t post it without any reason  ) and then I create train Image folder.
But there some parts of that Dataset realisation, maybe it’ll be useful for someone:
At the beginning we __init__ list of paths:

…
def __init__(self, files, mode):
super().__init__()
    # list of files to upload
    self.files = sorted(files)

…

Then we define upload function:

def load_sample(self, file):
image = Image.open(file)
image.load()
return image

Notice that you should use from PIL import Image
And at the end we define __getitem__:

def __getitem__(self, index):
…
    x = self.load_sample(self.files[index])

…
return x