Method GetPageColorSpaces() not working?

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Hello all,
on my search for a way to check, if RGB images are contained in an existing PDF file i found the method GetPageColorSpaces(). Supposing that this was exactly what I was looking for, i tried to iterate through the pages of the PDF file and call the method. No idea why, but it always returned an empty string.
Did I get the main purpose of this method wrong or do I need anything else to retrieve color space information (additional libraries, etc.)?

Regards,
Martin

My code looks something like this:

bool rgbFound = false;
for (int page = 1; page <= this.Library.PageCount(); page++)
{
    this.Library.SelectPage(page);
    string colorSpaces = this.Library.GetPageColorSpaces(0); // colorSpaces is always ""
    if (colorSpaces.ToLower().Contains("rgb"))
    {
        rgbFound = true; 
        break;
    }
}
if (rgbFound)
{
    ...

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martin.weigl Members Profile Find Members Posts Team Player Joined: 23 Feb 16 Location: Upper Austria Status: Offline Points: 27	Post Options Post Reply Quote martin.weigl Report Post Thanks(0) Quote Reply Topic: Method GetPageColorSpaces() not working? Posted: 21 Apr 16 at 1:43PM
	Hello all, on my search for a way to check, if RGB images are contained in an existing PDF file i found the method GetPageColorSpaces(). Supposing that this was exactly what I was looking for, i tried to iterate through the pages of the PDF file and call the method. No idea why, but it always returned an empty string. Did I get the main purpose of this method wrong or do I need anything else to retrieve color space information (additional libraries, etc.)? Regards, Martin My code looks something like this: bool rgbFound = false; for (int page = 1; page <= this.Library.PageCount(); page++) { this.Library.SelectPage(page); string colorSpaces = this.Library.GetPageColorSpaces(0); // colorSpaces is always "" if (colorSpaces.ToLower().Contains("rgb")) { rgbFound = true; break; } } if (rgbFound) { ...

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: 21 Apr 16 at 9:18PM
	Hi Martin, GetPageColorSpaces will collect the device-tags if there are any. It's not a must to have devicetags for coloured pages. You can have cmyk-colours without a /DeviceCMY inside and you can have rgb-colours without a /DeviceRGB. Better: You can have a b/w-page with a /DeviceRGB inside. Here a piece of code with notepad out of a pdf of mine: << /Filter /FlateDecode /Height 28 /Length 206 /BitsPerComponent 1 /Width 688 /ColorSpace [ /Indexed /DeviceRGB 1 (‡¦›Ù ·) ] /Subtype /Image /Type /XObject You can see /BitsPerComponent 1 ... and this mean b/w-page You can see /DeviceRGB ... but it's from a b/w-page. Searching for a sample for you i've to check many pdfs 'cause often the device-tags were missing.
	Cheers, Ingo

martin.weigl Members Profile Find Members Posts Team Player Joined: 23 Feb 16 Location: Upper Austria Status: Offline Points: 27	Post Options Post Reply Quote martin.weigl Report Post Thanks(0) Quote Reply Posted: 22 Apr 16 at 11:30AM
	Hi Ingo, thx. Now I have an idea, why GetPageColorSpaces() doesn't return anything: no device tags in the PDFs. Thx, martin

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: 22 Apr 16 at 10:13PM
	Yes... but coloured elements (rgb or cmyk) can be inside without a tag :( That's pdf ... or that what somebody doing with it ;-)
	Cheers, Ingo

martin.weigl Members Profile Find Members Posts Team Player Joined: 23 Feb 16 Location: Upper Austria Status: Offline Points: 27	Post Options Post Reply Quote martin.weigl Report Post Thanks(0) Quote Reply Posted: 25 Apr 16 at 1:13PM
	Hi Ingo, thx for your help! Regards, Martin