You really seem to be missing my point throughout this entire discussion 
because, for reasons unknown, you refuse to read up on what you are doing.

So I'll give you actual URLs for you to read:


Let's start with the difference between Raster images 
(<http://en.wikipedia.org/wiki/Raster_graphics>) and Vector images 
(<http://en.wikipedia.org/wiki/Vector_graphics>).  

In PDF (<http://www.adobe.com/devnet/acrobat/pdfs/PDF32000_2008.pdf>), this is 
the difference between an Image XObject (ISO 32000-1, 8.9) and Form XObjects 
(ISO 32000-1, 8.10).  As you can see from your PDF fragment below, you have the 
latter, where all the previous ones you had are the former. Form XObjects 
consist of a content stream of graphic objects (ISO 32000-1, 8.2), which is 
what you seem intent on calling a "gs stream", but is simply part of the PDF 
standard.

Hopefully after reading all the above, you will understand what you have and 
you can consider what you wish to do with it with respect to your "assignment".

I will point out, however, that OPI is a deprecated feature of PDF and hasn't 
been used in years since it interferes with the transparency model of PDF that 
was introduced in version 1.4.  Instead, the new model are Reference XObjects 
and PDF/X-5g (<http://en.wikipedia.org/wiki/PDF/X>).

Leonard Rosenthol
PDF Standards Architect
Adobe Systems

-----Original Message-----
From: alchemist [mailto:[email protected]] 
Sent: Tuesday, November 16, 2010 7:45 AM
To: [email protected]
Subject: Re: [iText-questions] Decoding Images




> What do you mean by "image"?  Raster image?  Vector image?
> 
The image is in gs notation I assume vectored (similar to and EPS)

Here is some background:
I am trying to extract FPO low res images that appear in a PDF document
(those appearing with OPI comments). For the most part I have been
successful extracting images of various different formats and encodings
(applying the appropriate decoder where necessary).

I decided to used some random different files for testing (I chose this one
at random from the internet) and I have problems:

http://media.wiley.com/product_data/excerpt/18/EHEP0000/EHEP000018-1.pdf

Now I know the image exists (it's a little key symbol) because I can see it
on the page so the image is there somewhere (the low res one). Note the F
PdfName refers to the high res image (which I don't care about for now)

This is the object which is identified (for page 3) as the OPI reference for
the image. Normally it would have image but it is a form in this case.

^M25 0 obj<>>>/Subtype/Form/Length 70/Filter/FlateDecode/Name/Fm20/Matrix[1
0 0 1 0 0]/Resources<>/ProcSet[/PDF]/ExtGState<>>>/Type/XObject/BBox[0 0
1332.0 783.0]/FormType 1>>stream 

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Spend less time writing and  rewriting code and more time creating great
experiences on the web. Be a part of the beta today
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Many questions posted to this list can (and will) be answered with a reference 
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Please check the keywords list before you ask for examples: 
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