Creating watermark with transparency on jpeg using PIL?

[tvmaly]

I have been trying to add a watermark to a jpeg using PIL, but the
watermark has a black box around it. I looked at

http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/362879

and

http://mail.python.org/pipermail/python-list/1999-May/003369.html

but I think these only refer to gif or png. I know jpegs really do not
support transparency, but is there some way to take a watermark in a
non jpeg format and add it to a jpeg without that box appearing around
it?

Best Regards

Ty

 

[Terry Hancock]

I have been trying to add a watermark to a jpeg using PIL, but the
watermark has a black box around it. I looked at [...]
but I think these only refer to gif or png. I know jpegs really do not
support transparency, but is there some way to take a watermark in a
non jpeg format and add it to a jpeg without that box appearing around
it?

Jpeg is a lossy compression format. You shouldn't do image processing
in such a format at all. Convert the data to PNG, do your processing,
and convert back to JPG for delivery. PIL can do that.

 

[Max Erickson]

You need to pass a mask in when you paste in the watermark.

see the documentation for the paste method at
http://effbot.org/imagingbook/image.htm
for more information

This should at least get you started...

Here, the alpha channel of 'mask' is used as the mask.

max