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Extracting image transparencies

Posted: Tue Jan 31, 2017 6:26 pm
by Timur Born
Hello.

Is there any way to make PDF Tools save image transparencies upon extraction? It seems like it always turns transparencies into black (0/0/0), which causes problems with some images. Adobe DC seems to turn transparencies into white (255/255/255), which also causes problems with some images.

PDF Tools already is capable of extracting image transparencies when it exports to Word or Powerpoint. So it should be quite possible for image extraction, too?!

Re: Extracting image transparencies

Posted: Wed Feb 01, 2017 7:51 am
by Timur Born
Extracting a PDF to images allows to set the background color, including "none", aka transparent. But the tool that extracts images out of PDF files has no such option and even though PNG and TIF can save transparencies they are converted to black.

Re: Extracting image transparencies

Posted: Thu Feb 02, 2017 9:09 am
by Will - Tracker Supp
Hi Timur,

Thanks for the post - I've just confirmed this here. I'm not sure if this is a planned feature, or if it's a bug. I've passed it along to the Dev. Team for comment and will let you know when I hear back.

Unfortunately (as you've probably noticed) I'm still in the U.K. and the lead dev. of PDF-Tools is in the Canadian office, so I may not hear back until late today/early tomorrow.

Cheers,

Re: Extracting image transparencies

Posted: Thu Feb 02, 2017 9:19 am
by Timur Born
No hurries. Travel save!

Re: Extracting image transparencies

Posted: Thu Feb 02, 2017 9:25 am
by Will - Tracker Supp
I'm here for another 2 months now, I'm afraid, so I'll have to communicate to them from a distance :(

Re: Extracting image transparencies

Posted: Fri Feb 03, 2017 8:12 am
by Will - Tracker Supp
Hi Timur,

Heard back from one of devs. on - It's not a bug, but isn't something that we've implemented yet. He's said that this is somethingwe can implement, but it's too late to implement it in the upcoming release (build 320).

Thanks,

Re: Extracting image transparencies

Posted: Fri Feb 03, 2017 8:49 am
by Timur Born
Good to know, thanks for looking into it. One developer also replied to me that he implemented the ability to save single images directly to a file in Editor, so once transparency support is implemented it hopefully works for both programs. Just another reason to buy the whole Pro package even though I mostly only need Editor and look for a more sophisticated PDF printer to replace Ghostscript.

Re: Extracting image transparencies

Posted: Fri Feb 03, 2017 10:38 am
by Will - Tracker Supp
Hi Timur,

The Editor and Tools share the same core code-base, but I don't know if that will mean that this feature will work the same for both, I'll update the feature request to ask.

Cheers,

Re: Extracting image transparencies

Posted: Tue Mar 07, 2017 11:45 pm
by Vasyl-Tracker Dev Team
Check the new version of PDF-Tools - we have added the 'Keep transparency' option for 'Extract Images from PDF' action.

Re: Extracting image transparencies

Posted: Sun Mar 12, 2017 11:08 am
by Timur Born
Great, thanks you! I am just downloading and will check it out. I bought the Pro version, so to get access to all features. Of course I would still love to see this in Editor, too. ;)

Re: Extracting image transparencies

Posted: Sun Mar 12, 2017 4:27 pm
by Timur Born
Works great in PDF Tools, I am already using it! Now we need an option to save/extract (maybe even copy & paste?) images with transparencies directly out of Editor for single images, instead of dozens and hundreds. ;)

Re: Extracting image transparencies

Posted: Sun Mar 12, 2017 8:44 pm
by Will - Tracker Supp
Hi Timur,

I believe that this is being worked on as well, but I'll need to double check that. I'll keep you posted as best I can.

Cheers,

Re: Extracting image transparencies

Posted: Wed Mar 15, 2017 9:13 am
by Timur Born
Here is a curious observation. Using transparencies fixes one image where PDF Tools (and some web-sites I tested) show an image part that is not visible in the original PDF and not in the version with transparencies. Acrobat extracted this correctly using white instead of transparencies, but the black Tools (and web-sites) versions adds the extra bit.

No idea how this happens, because this definitively is no transparent or even solid color part. Maybe there is some alpha-channel information in only those parts? Look at the bottom part of this image (reddish extra frame).

Image

Image

Anyways, the transparent version corresponds to the PDF version, so it's good to have transparencies as an additional option now.