Detecting Colour in a PDF

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Is there a function for detecting if a PDF has colour on any of the pages other than black and white?

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Doc-ItMan Members Profile Find Members Posts Beginner Joined: 15 Nov 11 Status: Offline Points: 5	Post Options Post Reply Quote Doc-ItMan Report Post Thanks(0) Quote Reply Topic: Detecting Colour in a PDF Posted: 24 Jul 12 at 3:09PM
	Is there a function for detecting if a PDF has colour on any of the pages other than black and white?

Ingo Members Profile Find Members Posts Moderator Group Joined: 29 Oct 05 Status: Offline Points: 3524	Post Options Post Reply Quote Ingo Report Post Thanks(0) Quote Reply Posted: 24 Jul 12 at 9:22PM
	Hi Doc! There's no implemented function for this. You can do it by your own. I've posted some code little time ago. Use RenderPageToStream and put the content into a small (64 x 64 or so) bmp-image. Now you can check the pixels if there's any other colour than black or white. Here's the link: http://www.quickpdf.org/forum/forum_posts.asp?TID=2194&KW=Round%28pix%29&PID=9362&title=this-tif-cant-be-converto-pdf#9362 Cheers, Ingo

Doc-ItMan Members Profile Find Members Posts Beginner Joined: 15 Nov 11 Status: Offline Points: 5	Post Options Post Reply Quote Doc-ItMan Report Post Thanks(0) Quote Reply Posted: 24 Jul 12 at 9:30PM
	Thanks for the help. It is interesting that there is no such function for this. I do not believe that the PDF Spec includes it either.

AndrewC Members Profile Find Members Posts Moderator Group Joined: 08 Dec 10 Location: Geelong, Aust Status: Offline Points: 841	Post Options Post Reply Quote AndrewC Report Post Thanks(0) Quote Reply Posted: 27 Jul 12 at 5:07AM
	The closest and quickest function we have is GetPageColorSpaces. This will return a CSV based string showing all the colorspaces used in the document for images. If the string contains anything other than DeviceGray then there is a very good chance that colours are used in the document. This may not pick up coloured objects in the content stream but most PDF's have some type of image or logo. Andrew.

Doc-ItMan Members Profile Find Members Posts Beginner Joined: 15 Nov 11 Status: Offline Points: 5	Post Options Post Reply Quote Doc-ItMan Report Post Thanks(0) Quote Reply Posted: 27 Jul 12 at 7:01AM
	I could not find that method in the QuickPDF Library v8.12. Cheers Howard.

AndrewC Members Profile Find Members Posts Moderator Group Joined: 08 Dec 10 Location: Geelong, Aust Status: Offline Points: 841	Post Options Post Reply Quote AndrewC Report Post Thanks(0) Quote Reply Posted: 27 Jul 12 at 8:09AM
	This is a relatively new function and is available in 8.15 / 8.16. QPL 8.16 is a free upgrade to all registered 8.xx users and contains many fixes and improvements over 8.11 and 8.12. It can be downloaded from http://www.quickpdflibrary.com/products/quickpdf/updates.php Andrew.

Ingo Members Profile Find Members Posts Moderator Group Joined: 29 Oct 05 Status: Offline Points: 3524	Post Options Post Reply Quote Ingo Report Post Thanks(0) Quote Reply Posted: 27 Jul 12 at 1:47PM
	Hi! There's no need to use ColourSpaces if you want to create coloured pdf-documents. There could be DeviceRGB but the content is absolutely b/w... and there could be no ColourSpaces and the content are coloured images. It's not a save method. There are many printing services out there and the customers have to pay more for coloured printouts than for b/w. I've few customers using my solution i've described above. Cheers, Ingo Edited by Ingo - 27 Jul 12 at 1:48PM

AndrewC Members Profile Find Members Posts Moderator Group Joined: 08 Dec 10 Location: Geelong, Aust Status: Offline Points: 841	Post Options Post Reply Quote AndrewC Report Post Thanks(0) Quote Reply Posted: 02 Aug 12 at 11:40AM
	Currently, the only 99.9% correct way of detecting colour in a PDF would be to render the page to a BMP file and then checking each and every pixel - basically following Ingo's method. Some commercial design and printing customers need to know about the various plates and colorspaces used by a PDF and that is where GetPageColorSpaces comes in handy and is why I mentioned it as the answer hopefully may be useful for some people reading this. Andrew.