Extracting custom EXIF data from PNG files

🚀 The feature

Being able to use torchvision.io.read_image(...) to read PNG files alongside the custom metadata stored in the exchangeable image file format (EXIF).

Motivation, pitch

I am training different deep learning models and some of them rely on custom metadata stored in EXIF inside PNG files.
Currently I have to do

from PIL import Image

with Image.open(file_path) as image:
    image.load()

  if image.format == "TIFF":
      metadata = image.getexif()[37510]  # 0x9286
  else:  # png
      metadata = image.text

but would much rather just ditch PIL.Image and do

from torchvision.io import read_image

image, metadata = read_image(file_path, read_metadata=True)

Alternatives

No response

Additional context

No response

Edit

added case distinction between TIFF and PNG files

Start at the torchvision.io.read_image entry point and review how PNG and TIFF images are currently decoded and how metadata is exposed. Compare the requested PNG custom EXIF behavior with the shown PIL examples; done means read_image can return the image together with the requested PNG metadata.