When copying or extracting images with transparency/alpha channel data from Adobe Reader X for Windows, the resulting file does not contain an alpha channel and all areas that should be transparent are 100% black.
One of the publications I read provides subscribers of their printed works with a free copy of the PDF as well (Paizo Publishing in this case). The publications are created on Macs in Adobe InDesign, password locked, and then personalized with the subscriber's email for security purposes. The publisher allows customers to utilize the graphics for private/personal use, which is what I am trying to do.
For a couple years I have used Some PDF Image Extract to export the images. This works great for rectangular things like maps or full-page graphics, but illustrations with text wrapping around them run into the transparency issue.
With these images, that transparency/alpha layer has been used to mask the images so that they do not blot out the text.When exported, the image's alpha channel is lost, and all the areas that are supposed to be transparent are 100% opaque black. I tried another product called "PDF Image Extraction Wizard" and even when selecting TIFF or PNG no alpha channel is present in Photoshop (I'm using CS3 for Windows). The only channels are RGB, Red, Green, and Blue — no alpha.
Next, I tried what the technical director of the company said he does: he simply drags the image from Reader X (Mac), and drop it on his desktop. He said on his Mac this forms a TIFF with an alpha channel, and he assured me that he's using the free copy of Reader X and not Acrobat Pro. When I try this on my Win7 box (x64 if it matters), I get a circle with a line thru it. It appears Reader X (Windows) does not support dragging and dropping of images to the desktop in Windows.
Discussion on publisher's site is here: http://paizo.com/paizo/messageboards/paizo/websiteFeedback/computerHelpRequired
The next thing that he (and some Mac users on the site) suggested was to simply copy the image and paste it into another program. Another user stated he could copy/paste to a Mac program called "Preview" and the alpha channel was intact. However, when I perform a copy on an image in Adobe Reader X (Windows), and then create a new file and paste in CS3 (Windows), once again, all of the areas that should be transparent are still 100% black.
Since the people who make the publication all use Macs, they really don't have any more advice they can provide. I've tried setting the background option (in Photoshop) to all 3 options (transparent, white, background color) and even setting both the foreground and background colors to white, and there is no change.
Does anyone know of a way to extract the images directly while preserving transparency when using Reader X for Windows? (And no, taking a screen capture and cropping is not a viable option.)