png transparency with PIL

[Robin Becker]

I'm trying to determine the transparency information for a png image. With gif
images I can determine the colour that is used for transparent areas using
im.info['transparency']. For the png images of interest there is no such entry
in the info dict. I assume that's because of the way png does transparency. I'm
guessing I need the alpha channel, but is there a way to get hold of it?

 

[Bjoern Schliessmann]

I'm trying to determine the transparency information for a png
image. With gif images I can determine the colour that is used for
transparent areas using im.info['transparency']. For the png
images of interest there is no such entry in the info dict. I
assume that's because of the way png does transparency. I'm
guessing I need the alpha channel, but is there a way to get hold
of it?

For accessing the alpha channel, there is an RGBA mode for PNG
files:

http://www.pythonware.com/library/pil/handbook/format-png.htm

Regards,


Björn

 

[Robin Becker]

For accessing the alpha channel, there is an RGBA mode for PNG
files:

http://www.pythonware.com/library/pil/handbook/format-png.htm

........

that sounds like what I need.