Check if an image is transparent or not

Question

I'm trying to check an image is transparent or not using PIL.

image = Image.open(file).convert('RGBA') 
alpha = image.split()[-1]

This gives a value like this

<PIL.Image.Image image mode=L size=714x303 at 0x25EB0EBC040>

How to convert this to a transparency value? Or is this a right way to find the transparency of an image by converting it to RGBA?

What are you actually trying to do please? If you open an image and convert it to `RGBA` like that, every image you open will have a transparency channel because you added one, so it will not tell you if there was already an alpha channel before you started.... — Mark Setchell, Jan 07 '21 at 15:53

score 2 · Accepted Answer · answered Jan 07 '21 at 15:53

image.getextrema() gives the min/max ranges for each channel, so you could use that to check the range on the alpha channel:

image = Image.open(file).convert('RGBA') 
alpha_range = image.getextrema()[-1]

if alpha_range == (255,255):
    print("image is not transparent")

Edit: did a quick search. You could also add some checks on the image mode, see the answers here too python PIL - check if image is transparent

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