checking file's content type instead of extension

[serengil]

Tickets

#1169

What has been done

With this PR, we are now checking the file's content type instead of file's extension while we are loading facial database.

How to test

make lint && make test

[AndreaLanfranchi]

I discourage the use of imghdr as already shows "deprecated" and support will be removed soon. Maybe PIL is better

[serengil]

Good spot

[serengil]

Recommended way to determine file type with PIL is

from PIL import Image
img = Image.open(filename)
print(img.format)

But I do not want to load and open file. If this is the way, then I will prefer to use file extension.

[AndreaLanfranchi]

You have to read carefully the PIL documentation for the open method on image:

This is a lazy operation; this function identifies the file, but the file remains open and the actual image data is not read from the file until you try to process the data (or call the :py:meth:~PIL.Image.Image.load method).

Also img.format reads only as many bytes needed to parse the header (pretty much like imghder.what) hence the operation is very cheap.

[serengil]

Cheers!