The fault lies with PS. I will not repeat the endless tiring excuses of certain Photoshop engineers, but they think that "a channel is just a channel" and per se "Alpha does not equal transparency". Therefore many image formats require you to manually load the transparency info from a channel. This can be easily done by Ctrl+clicking on the thumbnail in the channels palette after converting the Background layer into a floating layer. You can then simply hit delete to remove the selected parts and get "real" transparency.
Can you explainyour method in more detail.
I double clicked the later title to create a floatin layer.
Then I went into Channels and CTRL clicked no the alpha layer which makes a selection of the correct portions of the image.
Clicking delete (or inverting selection and then clicking delete) doesn't get rid of everything.
Can you spell out what else I have to click on first - do I go back to the regular image in layers and then hit delete or apply my selection as a mask?
I did manage to fumble through things once, but if you don't mind spelling out the right method, I'd like to learn the right way.
Yes, of course, you must select the layer content to delete. deleting pixels in the mask itself will degenerate it and increase contrast. Alternatively, apply the selection as a layer mask. click on cthe respective icon at the bottom of the layers palette or use Selection --> Save Selection, with the destination set to This Document and a new channel (layer mask).
Thanks for taking the time to help.