I'm having issues with a .png file that I was given when I export my layouts into .pdf. I'm using InDesign CS5.
What it looks like in InDesign before I export it:
What it looks like in Preview after I export it:
My .pdf settings are are follows:
Adobe PDF Interactive
I've also tried Embedding the Page Thumbnails and changingmy Image Color Settings. The document Transparency Blend Space has been changed to RGB. I end up resorting to exporting all of my layouts as JPEGs and then placing them into a new document the exporting to .PDF that way. It's a pain!
Are you viewing in Mac Preview or some other viewer other than Acrobat or Adobe Reader?
Some older applications also didn't use an alpha channel for the transparent bits, either. If it isn't simply a Mac Preview issue, try opening it in Photoshop and if the black is still there around good ol' Texta, use the wand to select and delete it. Save it back out.
If all esle fails, can you upload the actual PNG?
Take care, Mike