Check if image has alpha channel

I just discovered this command (in the Properties and Relations sections of the AlphaChannel command)

ImageMeasurements[img, "Transparency"]

It returns True if there is an alpha channel and False otherwise.

How about this:

RemoveAlphaChannel[img] == img

If img has no alpha channel, this returns True, but returns False if img has an alpha channel.

SetAlphaChannel[img] == img

seems to work too, but with the reverse logic.

As of V12, Information can return this:

enter image description here

Information[ExampleData[{"TestImage", "Lena"}], "Transparency"]

False

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