Talk:Portable Document Format/Archive 3

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Why called PDF?

Where does the name come frome? Aren't all files "portable"? I can e-mail .doc and .ofm just as well. Just wondering why pdf.

i think the first sentence now addresses this, perhaps somewhat (points 1, 2 & 3): PDF is used for representing two-dimensional documents in a (1) device-independent and (2) display resolution-independent (3) fixed-layout document format. That is to say, you can email any doc, but they'll appear quite different unless they're PDF or PS, hence, not "portable", i suppose. Michael (talk|contrib) 06:49, 23 July 2007 (UTC)
Portable means also platform independence, i.e. PDF can be generated, processed, and rendered on many platforms. --AFBorchert 15:50, 3 December 2007 (UTC)
... also can contain embedded resources, unlike HTML that links to external files -- (talk) 11:56, 10 June 2008 (UTC)

I Disagree

I don't know how this became an ISO standard. Is this a new way to market software, by making an ISO standard for it's format? There are several statements in this article that are simply not true. PDF is not an open standard. It is a proprietary format. It is not software independent. PDF is not even a good format. It is unlikely it will become the defacto standard for web documents as the article implies. The whole point of web documents is to separate content from presentation (e.g., HTML, XML). I assume this article was written by someone in Adobe and is clearly marketing fluff. Mingramh (talk) 13:12, 7 May 2008 (UTC)

I believe that Lee Harvey Oswald acted alone, I believe there oughta be a constitutional amendment outlawing Astroturf and the designated hitter. —Preceding unsigned comment added by (talk) 02:52, 8 May 2008 (UTC)

"Further criticism"

I was tempted to remove the following paragraph, but there may be something in there, which I do not understand:

"Further criticism is also centered around the restrictive, proprietary nature of the format, which does not allow free, direct encoding and modification of documents in PDF."

What does "free" mean here? Surely with a text editor, you can go in and modify any PDF file, as much as you want. You cannot usually add a paragraph to a text, and I think it is valid to mention that restriction, but that has nothing to do with the fact that the format is proprietary.

What does "direct encoding" mean? Are we talking about encryption or character set? If it is encryption, it seems the "criticism" simply is that the encryption algorithm is not free. But then, no one "criticises" Word for not being free, do they? I do not see any problem with the character set in later PDF formats, even though it could be messy in earlier version. Mlewan 08:19, 9 January 2007 (UTC)

This seems, to be honest, to be nonsense. If the comment is that PDF files are hard to directly edit and create (without using software), because of the complexity of the design of PDF, this is true (relative to simpler formats), but is unconnected to the proprietary origins. If this is stating that it is difficult because it is proprietary, this makes no sense: the PDF specification is readily available. If it is saying that because it is proprietary, free/open source software is not allowed, this is just wrong. So I have removed it. Of course, if I've completely misunderstood a valid and verifiable criticism, it only needs to be added back with a suitable source. Notinasnaid 09:30, 9 January 2007 (UTC)
Is it really relevant whether the criticism is valid? All that would be needed is a reliable source showing that this is a common criticism. Those who think it's a bad criticism (and I include myself) could cite sources refuting it. I agree with the deletion but I think it's an unnecessary distraction to argue about whether the criticism is correct; WP:NOR is a sufficient reason to delete it. Mrhsj 16:51, 9 January 2007 (UTC)
Quite right. Verifiable is enough; I should not have said "valid". However, it does need to be comprehensible. Notinasnaid 17:47, 9 January 2007 (UTC)

There are two potentially valid points that might be made. It is possible that the basic internal file format of pdf is such that it is difficult to modify/edit the contents. And it is very likely that part of the current wave of security features of all sorts is to intentionally make it extremely hard to edit/modify the contents of pdf files that use such security features.-- 16:42, 12 February 2007 (UTC)

Reverse engineering a pdf

Something about how to reverse engineer a pdf back to the point where it was saved as a pdf would be useful on this page. People are always asking me if they can do this; as i have only a hazy idea that there are tools out there that can do it I usually sidestep the question. Daveches 10:33, 24 January 2007 (UTC)

That isn't relevant to the article, which just describes the file format. There are plenty of tools which can work directly with PDF files. Chris Cunningham 11:40, 24 January 2007 (UTC)
The buzzword you want is "extraction": you're just getting out content, not reverse engineering which means something quite different. Notinasnaid 11:52, 24 January 2007 (UTC)
The buzzword is not necessarily "extraction": it's often about fomatting as well as content. eg if I have Microsoft Word on my machine and the PDF was saved from Word, can I get back to the Word document with all its formatting (eg to make a change then resave as PDF?)Daveches 21:37, 26 February 2007 (UTC)
There are commercial tools that will attempt to convert a PDF to Word format. They generally do not do a perfect job. The fact that the PDF format typically does not preserve all the information required to represent its source word processing document is germane to the article and it would be reasonable to include a statement about this if someone want to take the time to write a good well-sourced one. But a discussion of the capabilities of particular tools would be off-topic - this isn't a tech support forum. Mrhsj 04:56, 27 February 2007 (UTC)

Backwards Compatibility

The sentence about backwards compatibility should probably be deleted or changed. 1) No Backwards_Compatibility means newer readers can't read (some) older files, not the other way around - what the article currently claims. 2) Backwards Compatibility is almost always a function of the particular reader software used, not the format itself. Because this article is about the format, the statement is very confusing. I've also found no reference to backward compatibility issues online, and I'm inclined to think that the original author of that sentence was just frustrated because old reader software doesn't open new PDF documents; but that isn't really a backwards compatibility issue. Dana Powers 16:18, 1 March 2007 (UTC)

The sentence originally read "forwards-compatible." I wrote that, and that's what I meant. Someone changed it to backwards-compatible, which is incorrect. To me, saying "the format is backwards compatible" means that a reader written to a new specification will be able to open files written to an older specification. To say "the format is forwards compatible" means that a reader written to an older specification will be able to read a file written to a newer specification. The PDF format is backwards compatible; it is not forwards compatible. Mrhsj 17:14, 1 March 2007 (UTC)
Ahhh - which makes way more sense. It should definitely be changed back to forwards compatible then. Right now its just a logically confusing sentence. A cite would also be nice, as would clarifying that this is a property of the specification itself, not just a single application. Dana Powers 18:53, 1 March 2007 (UTC)
I do not get the point. Is any format ever forwards-compatible? Not even common text documents of today can always be opened in old versions of vi, because text files now often are UTF16. Check out .doc, .xls, .123, .rtf, .psd, .tif... Is any of them or any other format forwards-compatible? Mlewan 18:57, 1 March 2007 (UTC)
It is extremely difficult to achieve forward-compatibility, to be sure, which explains why most of the document formats you mention are not forwards-compatible. But it isn't impossible. Dana Powers 19:51, 1 March 2007 (UTC)
I've investigated a little further and found the BX and EX operators (this in the 1.3 spec; I haven't looked at others). They allow a PDF writer to specify that certain commands in a particular document should be ignored when read if they are unrecognized. This would allow creation of forwards-compatible PDFs, but it doesn't require it. Dana Powers 19:51, 1 March 2007 (UTC)
Yes. There are features in PDF that were intended to facilitate forwards-compatibility. That's why I rewrote the statement that said the format "wasn't designed" for forwards compatibility - it kind of was, it just didn't fully achieve the goal. I don't have a copy of the 1.0 spec so I can't do a proper sourced statement, but I recall that it promised that if a non-compatible change were ever introduced to PDF (one that would break an old reader completely) then the PDF version number would be bumped to 2.0. But such changes were in fact made (e.g. with the introduction of Flate in 1.2 and Object Streams in 1.5) without the major version being bumped. Mrhsj 05:13, 2 March 2007 (UTC)

Openness and old Microsoft rumors.

I deleted this material: "(There is now some contention whether PDF will truly be an open standard in light of Adobe Systems threatening to sue Microsoft Corporation for including the ability to write PDF's in some of their products, see external links.)"

Here's the history: in June 2006 Microsoft decided to change its PDF export tool from a bundled add-in to an add-in users would have to go their website to download. They claimed this had something to do with a threat of a lawsuit from Adobe, but this was never confirmed and no suit was filed. Then in January 2007 Adobe announced it was going to submit PDF to a standards body.

I don't see how those facts support the claim that "there is 'now' some contention...". That statement would require citations showing that there has been controversy *since* the Jan 2007 announcement, and that that controversy had something to do with this old rumor. Mrhsj 04:10, 15 March 2007 (UTC)

Agreed. The reported existence (or threat) of this antitrust suit has been widely used to support all manner of tenuous conclusions, in this article and elsewhere. Notinasnaid 08:43, 15 March 2007 (UTC)
It may be worth noting a particular error: some people assume that because Adobe is reported to be considering a suit because Microsoft may add PDF creation to Office, that therefore it must be because PDF is a secret, or requires a payment or license to develop for, and Microsoft don't have Adobe's permission for this. To be clear, no permission is needed, PDF is not a secret, and these are not the grounds for the reported threat of a law suit. Notinasnaid 08:56, 15 March 2007 (UTC)
I suggest the you STOP removing any discussion of the openness of PDF until you can point to ONE article from ANY source where a representative of Adobe states that they have no intent to sue Microsoft (or any one else) for inclusion of PDF code in Office 2007 (or any other product). This smacks to me of someone who has a strong vested interest in Adobe and is not interested in unbiased reporting of the facts. It should also be noted that handing a specification over to a standards body does not in itself make the standard open in any real sense. Please review the situation with the JPEG standard which was built from the ground up as an open standard, but was the subject of extensive litigation years later. Forgent Networks sued over 30 corporations for patent infringement for creating applications that could read and write in the JPEG "standard".
So, come forward with VERIFIABLE proof of your claims that PDF is an open standard with no threat of litigation, or stop removing discussion of this issue. It is critical information to anyone that is considering adding PDF support to an application they may write. Your whitewashing of the issue does not help. - Sincerely, a non-Adobe employee. —Preceding unsigned comment added by (talk) 22:25, 20 March 2007
I believe you are mistaken. The burden is not on editors to show that that Adobe have denied an intention to bring a suit against Microsoft. The burden falls on an editor who wants to add information that it is verifiable. The suit has been reported, but drawing conclusions about the openness of the standard from the suit seems to be entirely different, and this requires a reliable source. Reports I have read sugest the suit relates to anti-trust issues, not intellectual property or standards. You also seem to be confusing open standards with patent issues; these are entirely different things. Some open standards contain acknowledged patents and some are alleged later. However, there is disagreement on the definition of "Open standard", please see the article for details. If you are interested in Adobe's statement on the intellectual property issues connected with PDF, please see section 1.5 of the PDF Reference. Notinasnaid 22:52, 20 March 2007 (UTC)
I still disagree, my points are very well documented. There are at least 10 articles from reliable sources that discuss the pending lawsuit, but NONE that state there is no threat of lawsuit. How can you continue to state that the "burden falls on an editor who wants to add information that is verifiable". My information is completely verifiable, yours is not. Also you state that "suit relates to anti-trust issues, not intellectual property or standards". Well, it doesn't matter what the suit relates to directly. It directly influences the format and is critical information that someone who comes to Wikipedia might need to know (e.g. if they are deciding if they can add PDF export to their product). If you still disagree I suggest an independent third party review what is verifiable and decide if this information should be shown in the wiki entry. So far I see little to convince me that you aren't just an employee of Adobe who has a strong vested interest in showing that company in a positive light. I don't work for Adobe, Microsoft, or any other company that has a vested interest in the PDF/Markup business. However I strongly suspect that you do. —Preceding unsigned comment added by (talk) 23:41, 20 March 2007
Please try to rein in the personal attacks and let's focus on the article content. If this article reports the lawsuit it can only report what the reliable sources say. If the source draws conclusions, it can report those conclusions (as quotes, if they are not universally agreed). But if editors draw those conclusions, this is original research and clearly not allowed. My view is that what people planning to add PDF export need to know is in the PDF Reference, as defined above, do you have a reliable source that contradicts this Adobe source? Now, I'm going to wait and see what others say. Notinasnaid 00:17, 21 March 2007 (UTC)
I'm not making a personal attack, but I am questioning whether you are impartial. I think it is quite well established that impartiality is critical when providing public information. I believe you should state unequivocally whether you are financially compensated by Adobe so other readers can fairly judge your motivations. This becomes a critical issue over time since someone who is paid can keep arguing forever, whereas someone who wishes to add content because they believe it to be accurate and in the best public interest to distribute will eventually give up. Whatever the case, I hope a disinterested third party will make a judgement so I can move on. If they say I'm wrong and the information should not be present, I'll drop it immediately, but if they say the content should be present I think it should be added and you should be prevented from removing it. —Preceding unsigned comment added by (talk) 03:36, 21 March 2007
Well it's been a couple days and no third party has given an opinion. Unless someone offers an opinion soon, I'm going to add content discussing the lawsuit back in since it appears to be a simple difference of opinion and there is no consensus. Unless someone else rules, I expect that the content will be left in the article. Twikir 08:35, 22 March 2007 (UTC)
The rationale for removing it is still valid. This isn't a case of consensus, it's a case of policy, which says that random unsourced or poorly-sourced contentious material has no place on Wikipedia. (out of interest, are you the same user as the anon above?) Chris Cunningham 09:18, 22 March 2007 (UTC)
As I see it, the contention is whether the threat of suit by Adobe over Microsoft's attempt to add PDF creation functionality calls into question the concept of PDF as an 'open standard'. Do we have a reference that actually makes the above supposition? If so, put it in the article with the citation of the source and let's be done. If not, then the supposition is original research and it shouldn't go in. Whether Adobe actually has any intent to actual start litigation seems irrelevant to the issue at hand. Blade 15:43, 22 March 2007 (UTC)
I agree we shouldn't link the two. However I do think the lawsuit is relevant to PDF as a format and it should be mentioned in the article somewhere. Personally I would say it strange for Adobe not to deny the lawsuit if there was indeed no threat. While obviously we can't mentioned this in the article, it seems to me therefore likely that there was a threat. Most likely the threatened law suit was not copyright/patent (as even before Adobe annouced they were going to submit PDF to the ISO, you could still use it provided certain conditions are met) related but anti-competitive behaviour related 13:06, 20 April 2007 (UTC)

I'm not sure if the question was directed at me, but since I'm the one who removed the material in question, I'm happy to state that I do NOT have a conflict of interest on this topic as defined by Wikipedia. Mrhsj 21:06, 22 March 2007 (UTC)

The section Technical Foundations states that Adobe licences on royalty-free bases the patents on pdf. But the webpage to which this is referenced actually does not list any patent for which that is true. quote: ...Accordingly, the following patents are licensed on a royalty-free, nonexclusive basis for the term of each patent and for the sole purpose of developing software that produces, consumes, and interprets PDF files that are compliant with the Specification: U.S. Patent Numbers: But no patent number is listed. So it looks like that claim applies to no patent. If no one has a better reference I'd suggest to modify the text. Poderi (talk) 09:21, 3 March 2008 (UTC)

Haha! Looks like a problem with the styles on the Adobe web page. Actually the patent numbers ARE listed, but they're displayed in the background color, so they're invisible. If you select the text in that area and copy/paste to a text editor, you can see the patent numbers. Adobe just needs to fix their HTML. Mrhsj (talk) 18:54, 3 March 2008 (UTC)

Comparison of layout engines (XHTML) see also link

Is the "Comparison of layout engines (XHTML)" link under see also really relevant for this article, or am I missing something? --ScottyWZ 04:32, 17 March 2007 (UTC)

biast in the article

my question is why does this article have an advantages section and not a disadvantages section to me this is an obvious biast towards adobe. —The preceding unsigned comment was added by Dr noire (talkcontribs) 21:08, 13 April 2007 (UTC).

Well, add a section on it then. Just be sure that you cite your sources and the sources are verifiable. Avoid original research as well. Blade 16:40, 14 April 2007 (UTC)
It's a bit silly to call that a bias toward Adobe, since PostScript also came from Adobe, and PDF is their successor format. Kenahoo (talk) 14:09, 15 July 2008 (UTC)

Copyright violation?

The "Advantages" section seems like it has been picked up from PDF/A - Your Advantages, which is also acknowledged in the revision where it was added. It seems like a clear case of WP:COP to me, removing the content for now -- AshishKulkarni 16:48, 3 May 2007 (UTC)

HTML phoning home

"Like HTML files, PDF files may submit information to a web server." Can HTML files phone home? Sure, javascript embedded in HTML can, but HTML can't (AFAIK) --Taejo|대조 14:55, 13 May 2007 (UTC)

Well, in PDF's case it's also "JavaScript embedded in PDF" that actually phones home. So the parallel is pretty good. Mrhsj 22:04, 13 May 2007 (UTC)
Web bug -- (talk) 12:02, 10 June 2008 (UTC)

Some re-work to the organization of the content

I suggest that instead of "Technology" use "Format overview" and have the following sub categories (that follows the topics in the PDF reference 1.7):

  1. Imaging model
  2. Portability
  3. Compression
  4. Font management
  5. File generation
  6. Random access
  7. Security
  8. Incremental update
  9. Extensibility

With this, the article (at least the tech part) will be firly complete and describe the interior of the format. Any objections? Khecaji 13:13, 6 July 2007 (UTC)

Be bold. Go for it. Chris Cunningham 13:32, 6 July 2007 (UTC)

New wikiproject

Is there any interest in starting a wikiproject dealing with various representations av information (e.g. imaging models, presentation layer, content layer) and related methods for cross-referencing (e.g. integration of related information that exists in various digital as well as printed formats)? Dynamics of information and related problems.

PDF Catalog: part of PDF, application-specific extensions?

The PDF "Catalog" (search index) -- is this part of any type of PDF-related standard (eg, open specification?) or completely a proprietary closed-specification add-on to Acrobat? Can any PDF reader (eg, see "implementations") use the ".pdx" index file, and could any application generate the index (catalog) file? Michael (talk|contrib) 06:49, 23 July 2007 (UTC)

Icon Image

Perhaps some information on the traditional PDF icon images would be handy - especially the one used on Wikipedia when linking to a pdf file (it should be noted that finding the URL for this image seems all but impossible) - and perhaps even tell where one can actually access a public domain variant of this icon. I understand if that's too specified of a topic for this, but I'm sure there are people who could use it (including me). Shoreu 18:41, 27 July 2007 (UTC)

pdf (probability density function) 13:23, 31 July 2007 (UTC) Pdf is also a common abbreviation for Probability density function


Shouldn't this also be on the wiki of pdf?

It is on the Wiki. You have a link to it just there. To find it from the abbreviation you go through PDF_(disambiguation), which is linked to from the top of Portable Document Format. Mlewan 17:16, 31 July 2007 (UTC)

Editing PDF files

Could someone provide at least one example for this: There is also specialized software for editing PDF files. Palpalpalpal 06:39, 12 August 2007 (UTC)

Acrobat Professional. Nitro PDF. Foxit PDF Editor. Iceni InFix PDF Editor. Enfocus Pitstop. Jaws PDF Editor. Mrhsj 15:17, 12 August 2007 (UTC).

iText is an Open Source library for creating and manipulating PDF, RTF, and HTML files in Java. - 12:43, 19 September 2007 (UTC)


The article needs a great deal of additional material describing PDF file internal structure. Until then, reading a 1000 page reference manual is not an inviting place to start. Here are some options:

- 21:34, 3 October 2007 (UTC)

Your wish is my command. Just added some stuff; see if you like it. Mrhsj 22:53, 5 October 2007 (UTC)


I think the sentence "An up-to-date antivirus program is paramount" does not have to be in this article. —Preceding unsigned comment added by (talk) 14:16, 11 October 2007 (UTC)

Indic Support

I have issues with Indic Languages (including my mother tongue Tamil). I can covert a UNICODE word or any document to a pdf however when try to copy and paste back to Microsoft Word doesn't work. I tried various tools like doPDF, Acrobat but I don't have a solution. Is there any work around avaiable? or does it support most of the European languages only? please clarify. --Umapathy (உமாபதி) 17:48, 11 October 2007 (UTC)

CMYK jpgs

The image streams embedded in pdfs are sometimes jpgs (/DCTDecode) that can be extracted by hand into a file and viewed. But they are not always RGB; they may be /DeviceCMYK -- 4 bytes per pixel instead of 3? Which image viewers can properly handle CMYK jpgs? Irfanview sort-of recognizes the file type but shows false color, and then saves as a wrong RGB. Image Analyzer says it can handle CMYK, but does not seem to do it by default -- maybe with the ImageFileLib plugin? - 14:25, 19 October 2007 (UTC)

i am writing to ask about how do you send the PDF files to the internet and can you send me some files on dida ict courework and some other files thank you —Preceding unsigned comment added by (talk) 16:29, 5 November 2007 (UTC)

This 10 mo. User Barnaca is CENSORING My contribution

Ok so this user

is removing my table which outlines pdf conversion options (their pros and cons by price and user-friendliness and comments etc.) I didnt read my messages and resposted it because my table was removed the moment I put it on.

So I want to know what PDF conversion options are there , right. How do I find out ? I start a table on wikipedia listing the pdf converstion options. Since I only know two tools Acrobat Professional and cutePDF (which is two more than 99% of the world) I posted those two on the page. Now Mr. Barneca thinks I am spamming for Cutepdf. The software is free! my professor recommended it for our class but I didnt find it entirely useful because evne though its easy to use the darn thing only converts one way -> all formats to PDF. I also tried Acrobat Professional conversion option but that didnt work so well so I posted my observation. Now for heaven's sakes is this clear that I am not a spammer? Could you please stop being the censor here and permit me to put some foundation for finding out the converstion options I have?

If you dont want me to a put a table or something with applications working with PDF standards how else would you want me to frame this? How would you suggest I start a framework which others could fill with information regarding PDF converstion options? Is not a table listing the applications, their cost, their usability and their TO FROM conversion fields appropriate in this scenario? This is really absurd. —Preceding unsigned comment added by (talk) 18:45, 7 November 2007 (UTC)

I see two issues:
  1. Whether you are "spamming" or not. It looked like it to me. I might be wrong. I'll assume the best, that you aren't, and apologize for jumping to conclusions and not assuming the best earlier.
  2. Whether this information belongs in the article or not. I think it does not. Wikipedia isn't a buying guide, and I don't think comparison tables about products belong in an encyclopedia article. You may not be spamming, but if we leave this table in, I guarantee it will be a spam magnet, and will soon be loaded with links to every PDF-related product imaginable. This is not "censoring" you, it's saying I don't think it should be here. If a consensus forms on this page to include such a comparison table, I'll gladly yield to consensus. It currently is unsourced as well, but I'll assume if consensus forms to include it, we can find references for everything.
I look forward to hearing other views. --barneca (talk) 19:16, 7 November 2007 (UTC)
My opinion is it was right to remove the table. First, a table of this sort does not belong here. Please see WP:NOT, especially the sections on "Advertising," "Directories," and "Sales Catalogs," and "Instruction Manuals." The topic of this article is "Portable Document Format," not "tools for creating files in the Portable Document Format." Second, even if it were right to include the table, the content was unacceptable because the content violated WP:NPOV, for example by calling one product's quality "Poor".
Both of you, please assume good faith. User Barneca has already apologized for calling the table "spam". Anonymous user, it is not appropriate to accuse user Barneca of "censorship." It was simply an edit. Wikipedia editors routinely remove content they believe violates site guidelines. Assume good faith and debate the merits of the content based on Wikipedia policy. Mrhsj 20:54, 7 November 2007 (UTC)

Deleted Microsoft section.

I deleted the section headed "Competing PDF Standards," which had the body, " Microsoft announced its competing PDF standard based on XML Parser Specification in 2005. In response PDF announced its own Mars project a year later following a breakdown in talks between the two companies over co-operation."

Reasons: First, the heading and beginning of section are nonsensical. XML Paper specification is not a "PDF Standard". What is a "PDF Standard" anyway? Second, "PDF announced..." is nonsense. PDF is a file format, and it doesn't know how to talk. Third, Mars is already discussed elsewhere in the article. Fourth, whether Mars was a "response" to XPS or not is a matter of conjecture, as is the question of whether it had anything to do with a "breakdown in talks" (between what two companies? Is PDF a company?). Such speculation needs to be identified as such an attributed to reputable sources.

I don't think the section added enough value to the article to be worth trying to salvage. Mrhsj 20:39, 7 November 2007 (UTC)

PDF Ebooks

I'd really like to get an ebook reader to alleviate eye fatigue and portability. The Sony Reader has poor support (in terms of the average pdf you might get from a website) and the new Amazon Kindle is much worse. Since most of my ebooks are pdfs, I thought I'd ask here why is it so difficult for portable devices to support the portable document format? Is there any reader that has good if not great support for pdfs? (talk) 20:50, 7 December 2007 (UTC)

The reader that currently has the best support is the iLiad, but it's fairly expensive (up from €500/500$ (yes, the EU/US price difference is fairly startling due to current exchange rates), which uses iPDF as a viewer, with different extra features available (bookmarking &c.), along with a Wacom system for making annotations/notes/whatever in them. (I've got one) Boombaard (talk) 21:24, 28 June 2008 (UTC)

copy protection using custom embedded fonts

Apparently, a new approach to protecting PDF content is to use software that generates "random" text, but also includes custom embedded fonts to make the document read and print correctly.

This makes it impossible to copy the text (search the document etc) as it will come across as random garbage when not viewed in the custom font(s) specifically created for that particular document, all without having to protect or restrict the PDF in anyway (protections that can be cracked anyway).

Now, as far as I can see this isn't mentioned at all on Wikipedia. Which programs have this feature? How well does it work? etc etc Any discussion or links much appreciated. (talk) 19:45, 21 January 2008 (UTC)

What is your source? Or an example of an obfuscated PDF? If it's just 1:1 letter replacement it should be easy to decode. —Preceding unsigned comment added by (talk) 23:32, 6 November 2008 (UTC)
What you are seeing is the use of subsetted fonts without providing a ToUnicode mapping to facilitate text extraction. As the PDF security features already allow text copying to be disabled I think it is more likely that what you are seeing is a buggy PDF writer that fails to embed the mapping from the font glyphs back to Unicode as recommended by the PDF specification. —Preceding unsigned comment added by (talk) 03:29, 15 November 2008 (UTC)
"As the PDF security features already allow text copying to be disabled" -- the pdf security options are pretty thoughroughly broken though......... Plugwash (talk) 00:02, 2 May 2009 (UTC)

Creating PDFs

I think a section on how PDFs are created would be useful, I'd add one myself but I don't know how to create a PDF.Dendodge (talk) 18:30, 9 February 2008 (UTC)

PDF editors and software printers are mentioned in the article, see also List of PDF software —Preceding unsigned comment added by (talk) 23:35, 6 November 2008 (UTC)

Viewers, editors, and tools

The above quoted page contains external links ( among them the sub-section "Viewers, editors, and tools".

I am trying to add the URL ( to our own website to that list.

I think that the URL has value to people and there are absolutely no strings attached. The website is free, there is no registration, nothing. It provides an online conversion capability so no software installation is necessary to create PDF files from proprietary content. People use the service after seeing the link in the Wiki Document and seem happy.

But the link is constantly deleted, being defined as "Spam" as "Shareware", etc. I seriously doubt any of the editors deleting the link have even so much as looked at the page it refers to. The section and subsection show links to e.g. Adobe (commercial software), Docudesk (dito) and many more. Our conversion page offers a place to convert a single document without having to buy anything, without the need to install software. A service to the community. No more, no less and I thus think that it is a valuable addition to a document such as this one.

Comments would be very welcome!

Ph wiki edit (talk) 13:57, 8 April 2008 (UTC)

I'd rather remove existing links to tools such as dwg2pdf or to tutorials such as "Use Photoshop to create PDF Documents". There is a separate page for List of PDF software. Engelec (talk) 23:07, 2 February 2009 (UTC)


Would it not be fair to add a criticism section, ie: takes ages to download on slower connections, causes computers to crash when they are opened without saving? (talk) 09:52, 29 June 2008 (UTC)

Certainly, if you can find reliable, current sources that make these criticisms about the file format itself, that would be appropriate. The examples you give are somewhat suspect though: all large files are slow to download on slow connections regardless of what format they're in. And I would be surprised if you can find evidence that the file format itself "causes computers to crash"; that sounds more like a tech support issue with some particular application, which would be well outside the scope of this article. Mrhsj (talk) 21:52, 29 June 2008 (UTC)
I think it would be quite valid to add a criticism section, even if it isn't specific file type. I believe many criticisms for PDF files would stem from two things, mainly the de-facto viewer acrobat reader/adobe reader and users using the PDF file type over better alternatives. I believe it is fair to criticize PDF due to the shortcomings of Adobe Reader because not only is it the de-facto viewer, it is also made by the same company who developed and maintains the PDF standard. Additionally, nearly every form of media that links to a PDF, be it a website or CDROM either includes a copy of Adobe Reader or links to Adobe's Adobe reader download page. Also, Adobe Acrobat and Adobe Distiller are the de-facto methods for creating PDFs and they themselves are subject to harsh criticism. Because of the strong coupling of PDF and Adobe Reader, Acrobat, and Distiller, any criticism aimed at these products can, IMO, be safely aimed at PDF as well. PDF is marketed extensively and almost exclusively by Adobe. Adobes marketing has lead to users making poorly informed choices of their export format. Criticisms of the DOC format stemming from deficiencies in Microsoft Word would be pretty similar in nature, and, i beleive, valid as well. At the very least a section on the incorrect usage of PDF over say asci text, HTML, or jpg/png would definitly be valid, along with a link to criticisms of Adobe Reader. —Preceding unsigned comment added by (talk) 20:41, 27 January 2009 (UTC)
This Article smells like it was written and edited by Adobe. Can someone find out if this is the case? (talk) 16:22, 28 January 2009 (UTC)
The DOC format isn't an ISO standard, afaik. PDF is also widely used with LaTeX, both for output and for embedded graphics, and for good reasons, without any need for Adobe software. On Mac OS X, PDF is a native format with good support in Cocoa, the viewer provided by Apple isn't Acrobat Reader, and creaing PDF files is as easy and as native as printing. Engelec (talk) 16:43, 28 January 2009 (UTC)
I would like to express my support for a "criticism" section based on the format and it's practical uses. A page(biased and old, I must admit, but still true) that explains some of the disadvantages is found at: -Oddwarg (talk) 07:00, 27 February 2009 (UTC)
I would like to see a Criticism section on this article, too. Even as recently as March 2009, I am hearing complaints of PDF not being open enough to export data reliably, with third party programs. Since PDF is a pillar of modern document formats, this is an important question - whether PDF formats are open enough. This article cheers Adobe's efforts to create PDF as an open standard, but it offers no insight into the other side of the argument. It is not hard to search for articles that take this position (am reading InternetNews article called "Adobe: Open but not Always Open Source" at the moment), so I personally would appreciate someone with some knowledge on the subject to include their thoughts on the subject here. -- (talk) 12:23, 14 March 2009 (UTC)
The thing about pdf (which can be either good or bad depending on how you look at it) is it is basically a metafile format. While text remains as text each line of text is a seperate object. A table is a load of lines with text objects in the grid formed by those lines. This is great if your goal is to preserve the exact layout of a document, it is not so good if your goal is to have a format you can easilly copy information out of.
Also there seem to be few good tools for getting anything more than text and bitmaps out of a pdf. Inkscape is looking promising though (debians version can already import pdf with high success rates afaict). Plugwash (talk) 00:01, 2 May 2009 (UTC)

ISO standard

Wow, PDF is so ubiquitous within the publishing circles that I kept thinking it was an international standard. I guess I was wrong. --Voidvector (talk) 04:22, 3 July 2008 (UTC)

nh —Preceding unsigned comment added by (talk) 11:07, 6 August 2008 (UTC)

No you weren't. PDF is an ISO standard. Engelec (talk) 22:56, 2 February 2009 (UTC)

Naming conventions for image file formats

Please see the discussion at Talk:Image file formats#Naming_conventions_for_image_file_formats on naming conventions for articles on image file formats. Dcoetzee 00:47, 25 October 2008 (UTC)

article is too web-centric

This article on PDF is very web-centric with the emphasis on downloading and viewing PDF files. I was involved in computer assisted typesetting at Kingsport Press from 1969 to 2003; I know that 2003 was an aeon ago in web-time, but we did PostScript and PDF from 1994 on.

PDF was a compressed, cross-platform compatible file format viewable on Mac, PC (Windows) and Unix, which was a big selling point. It was based on PostScript, which means that any typesetting device that supports PostScript should be able to print a PDF document. Before PostScript, every typesetting device used (VideoComp (Hell Digiset), Linotron 202, etc.) had its own incompatible device language. PostScript became a universal typesetter language and PDF became the universal typesetter file format.

PostScript (.PS) language and Portable Document Format (.PDF) file format established universal standards in a chaos of incompatible typesetting languages and file formats, changing type composition as we knew and practiced it. That is a very important aspect of both PS and PDF. Naaman Brown (talk) 23:00, 25 January 2009 (UTC)

Reference link failure

Current reference footnote #4 - History of pdf openness is 404 - Page not found. Did a search of to find a possible relocation. Found a top level page, but the content is indeed missing. Reference should probably be removed unless someone can find where this document has moved to.

GrandpaDave (talk) 07:17, 4 March 2009 (UTC)

Also searched the Wayback Machine for the missing document referenced at [1]. Document also not found there. Referenced material is essentially a history of releases. Will check for additional feedback and remove reference unless an alternate is found. GrandpaDave (talk) 01:55, 7 March 2009 (UTC)

"PDF format"

At three points in the article, it says "PDF format". Should this be removed? After all that means "Portable Document Format format", which is a tautology and so not proper English. Just a point. Greggers (tc) 23:08, 24 March 2009 (UTC)

PDF (from version 1.4) supports true graphic transparency; PostScript does not.

That sentence isn't possibly correct -- even though I've seen it in other places. Postscript primitive operators do not support true graphics transparency; postscript itself can do anything -- it's Turing complete. A PDF interpreter can be written in postscript. —Preceding unsigned comment added by (talk) 02:24, 1 April 2009 (UTC)

The sentence is correct. The imaging model is part of the language. No amount of Turing completeness in the programming part of the language can change the fact that the PostScript imaging model is an opaque one. And no, a PDF 1.4 interpreter cannot be written in PostScript, for precisely this reason. Mrhsj (talk) 15:36, 5 April 2009 (UTC)
Surely you could write code in postscript that read the pdf and combined the overlaping objects together before outputing them. Plugwash (talk) 23:48, 1 May 2009 (UTC)

Can files embed error messages?

I ran across something that piqued my curiosity. While using the PDF-XChange Viewer to read a pdf file, an error message popped up, with a standard message about not having the latest version of Adobe Reader. It seems strange to me that an alternative reader, like X-Change, would direct users to download the latest version of AR rather than their own software. So, basically it seems like there are several possibilities: 1)error messages can be embedded in the pdf file, 2)X-Change is being honest about their inability to render certain pdfs, or 3)The X-Change software is based on Adobe code. (talk) 05:36, 14 April 2009 (UTC)

Geospatially Enabled PDF

I suggest the addition of a section on geospatially enabled PDFs and the removal of GeoPDF page. GeoPDF is able to be created directly from ESRI's Arc 9.3 and used in Adobe software. The current GeoPDF page is a TerraGo advertisement. Miglewis (talk) 15:40, 8 May 2009 (UTC)

It's pity that.....

the following citations are not hypertext linked -- (talk) 06:38, 10 June 2009 (UTC)

Standard Type 1 Fonts

The title "Base 14 fonts" is confusing to the non-expert, as "base 14" in most other contexts refers to tetradecimal. The standard "Document management — Portable document format — Part 1: PDF 1.7" does not use this terminology, preferring instead "Standard Type 1 Fonts". I have changed this to clarify the heading. TimR (talk) 16:40, 8 September 2009 (UTC)

Okay, that works for me as long as we keep the expression "base 14 fonts" in the text as you have done. Although the expression doesn't appear in the Reference Manual, it does get 973,000 ghits - it is the common name used by everyone knowledgeable in the field. Mrhsj (talk) 16:52, 8 September 2009 (UTC)

Image Resolutions

When choosing between two different versions of the same digital photobook, one in PDF and the other as a collection of JPEG files, are there any builtin limitations to the Portable Document Format that render it inferior to its JPEG counterparts in terms of image resolution and quality?

This is supposedly related to PDF's inability to handle different image resolutions. Can someone please expand upon those hypothetical limitations? -- Ishikawa Minoru 18:29, 14 November 2007 (UTC)

There are no limitations in the ability of the PDF format to embed JPEGs. PDF stores JPEGs in exactly the same format as the original files. PDF has no "inability to handle different image resolutions". —Preceding unsigned comment added by (talk) 09:29, 24 December 2008 (UTC)
There aren't any such limitations inherent in pdf itself but the software used to create the pdf may well downscale images over a certain resoloution (usually this is configurable) to keep the filesize down. Plugwash (talk) 00:32, 26 October 2009 (UTC)

PDF = the file format? Why?

So a proprietary file format is more important that, say, probability distribution function? Geek war, ahoy! --Sigmundur (talk) 23:48, 30 October 2009 (UTC)

.pdf the only portable document format?

Is the format with the extension pdf the only portable document format? No other postscript print-ready formats out there? Wouldn't their generic name also be portable document format? (talk) 09:08, 3 December 2009 (UTC)

Obviously marketing had some influence over the choice of name. AnonMoos (talk) 00:54, 31 December 2009 (UTC)


Does anyone object to me setting up automatic archiving for this page using MizaBot? Unless otherwise agreed, I would set it to archive threads that have been inactive for 60 days.--Oneiros (talk) 16:20, 10 December 2009 (UTC)

Odd, the MizaBot page says, "Before requesting automatic archiving on an article's talk page or a Wikipedia forum, please establish a consensus that archiving is really needed there," but it looks like you set it up anyway. "No objection" within less than 2 days is probably not what they mean when they ask you to "establish a consensus," eh. (I myself would favour the Wikipedia guideline of 50 topics[2]). -- Mecandes (talk) 22:06, 15 December 2009 (UTC)
I observed the policy after placing the {{Archiveme}} template on a talk page. The archives already existed. Is automating them really a problem?--Oneiros (talk) 22:20, 15 December 2009 (UTC)

DRM restrictions question

Section "Usage restrictions and monitoring" states:

PDF files may also contain embedded DRM restrictions that provide further controls that limit copying, editing or printing. The restrictions on copying, editing, or printing depend on the reader software to obey them, so the security they provide is limited. Printable documents especially might be saved instead as bitmaps and subject to OCR.

Does this imply screenshots could be used to circumvent DRM restrictions of all PDF files? Regardless, wouldn't OCR from image files such as bitmap be a partial circumvention? It sounds to me like they could be used to create files that would be essentially the same as printing the PDF and scanning the printout. The basic text and image content would be freed from the DRM but some or all of the special functions or features of the PDF file would be lost in the transition; possibly with some variation of loss or retention depending on the format the OCR output was saved in. Moss&Fern (talk) 09:16, 11 December 2009 (UTC)

At least with conventional pdf protection you don't even need to go that far, there are plenty of tools out there that will strip the protection while leaving other stuff intact. Plugwash (talk) 11:17, 11 December 2009 (UTC)
This is exactly what happened with the Unicode spec: You can get PDFs with some glyphs, but they are DRMed. So someone made bitmaps of them and created a new PDF with all glyphs. OCR isn't really helpful for the complete Unicode spec. :-)--Oneiros (talk) 22:09, 14 December 2009 (UTC)
The second half of the paragraph does not make sense. Printable documents especially might be saved instead as bitmaps instead of what? Instead of PDF, instead of using DRM? Either way, that's beside the point: it has already been stated that the DRM is not secure. If nobody objects I'm removing it. -- (talk) 17:40, 27 August 2010 (UTC)

Worldwide usage?

I was hoping the article might give me an idea about how widespread the use of PDF files is; is it available in all languages and countries, and is it as accessible on computers worldwide as it is in North America? (Clearly that is the intent if it has been made an ISO standard, but is it so in actual practice)? -- Mecandes (talk) 22:06, 15 December 2009 (UTC)

The format is independent of the software, and what languages the software is offered in. Adobe_Acrobat has a section on Internationalization and localization and list of languages is rather large. Bragr 20:15, 8 January 2010 (UTC) —Preceding unsigned comment added by Bragr (talkcontribs)

PostScript POV

The section of PostScript gives a one-sided "PDF is better". While this is certainly something Adobe wants us to believe, it is not necessarily true---and many who have experienced both prefer PostScript. I note that PostScript is human readable, can be edit in in a normal editor (if needed), is much easier for third-party products to support, that "imperative programming language" brings certain advantages, that it is immediately understood by good printers, ... (talk) 02:06, 8 March 2010 (UTC)

The neutrality tag is inappropriate and should be removed: "Simply being of the opinion that a page is not neutral is not sufficient to justify the addition of the tag. Tags should be added as a last resort" (WP:NPOV_dispute). Nobody had rejected or reverted any changes that would present an alternative point of view. If you want to present alternative opinions (properly sourced of course), go ahead. If you don't offer a constructive edit to address the problem you perceive within a few days, I will remove the tag. Mrhsj (talk) 04:08, 8 March 2010 (UTC)
Removed the tag as explained above. Mrhsj (talk) 16:21, 17 March 2010 (UTC)
I think you are not allowed to do that. First of all, you're referring to an essay (WP:NPOV_dispute), not a policy. Essays are guidelines only. Secondly POV-tags, and its kin, can only be removed if the issue is resolved here on the talk page, or if the issue times out by three months. It isn't/hasn't. You removed it arbitrarily without reaching consensus. Thirdly IP makes a proper talk page complaint, so it cannot be considered added hastily. In order to NPOV a text, all "better" and "has several advantages over" should be attributed to a specific usage, and preferably be sourced. In order to NPOV the PostScript section, the different usages should be highlighted. Subjectively: of course PostScript is better for this, and PDF better for that. They're just purpose specializations. The template
reads: Please do not remove this message until the dispute is resolved. Rursus dixit. (mbork3!) 13:52, 11 September 2010 (UTC)
Okay it is true that the link I cited is an essay, not an official policy. However it is the essay that the POV tag itself links to as a reference for how to deal with it. Is there an official Wikipedia policy governing removal of POV tags? Please cite. Thanks. Mrhsj (talk) 15:57, 11 September 2010 (UTC)

Dead Links

Some of the External Links are dead, including the first one on the list. Instead of deleting them, can someone provide the updated links? AmanAhuja (talk) 18:52, 22 October 2010 (UTC)

I found only two dead links, and took a stab at at updating both: [3]. Not so sure about the AIIM one; maybe someone else can do better. TJRC (talk) 19:07, 22 October 2010 (UTC)

Portable Document Format or portable document format?

Hello, I reverted one edit in the article and changed first letters of the name "Portable Document Format" to capitalised letters. According to ISO 32000-1 specification:

Section 4 (page 7): "4 - Terms and definitions"

  • "4.38 - PDF - Portable Document Format file format defined by this specification ISO 32000-1".

Section Introdution (page 17)

  • ISO 32000 specifies a digital form for representing documents called the Portable Document Format or usually referred to as PDF.

-- (talk) 10:48, 11 February 2011 (UTC)

How to read a PDF file

The article needs some discussion on how to open a PDF file so you can read it. Most public computers I use CANNOT read PDF. They call for an association that has to be down-loaded, which is, in my situation, almost never possible. The idea that PDF files are universally readable is in error. (talk) 06:19, 12 April 2011 (UTC)

You may find this article instructional. Like most articles on software specs, the main article avoids talking about specific implementations, unless there is some notability (Adobe Acrobat and Reader are mentioned because they were the only official implementations when the format was proprietary). I believe the two most popular readers for Windows are Foxit Reader and Adobe Reader. --Nicholas Davidowicz (talk) 16:09, 12 April 2011 (UTC)
We have a list of PDF software but I don't see that helping you much if you can't run anything you download. You need to complain to the people in charge of those "public computers" and/or stop cheaping out and either get your own internet connection or find somewhere that actually cares about their users. PDF is a very common format and anyone offering a general purpose computer for internet access should really be offering a PDF reader. Plugwash (talk) 22:38, 12 April 2011 (UTC)

"Open standard"?

I question the description of this proprietary thing as "open standard". If this is allegedly an "open standard", why can I not access the source code of a PDF document and make changes? For example, I need to correct typographical errors in a document, but the publisher used an extremely obscure font that I'm not able to find anywhere. If the font is embedded in the document, this shouldn't be a problem if this was an "open standard", it would only be a problem for a very proprietary application that deliberately tried to prevent the document from being "open" -- and in any case, I'd be happy to use a different font to make changes such as adding a comma, I couldn't care less about the font that's already used. I'm aware that older versions of Acrobat Pro did not prevent you from editing text if you didn't have the exact same font installed. Potbirohotballa (talk) 15:03, 31 May 2011 (UTC)

Open standard does not mean any document can be opened and read by everyone. Open standard means the specifications for creating and reading documents are publicly available. --NeilN talk to me 16:02, 31 May 2011 (UTC)

Add "PDF searchable image" concept to the article?

There are a important PDF concept in the digitalization and OCR markets, the "PDF Searchable Image". It is produced by, ex., "Acrobat Capture" and "Capture SDK" Adobe products.— Preceding unsigned comment added by Krauss (talkcontribs) 23:27:52, 18 Jun 2011 (UTC)

Agreed. Virtually all computer-savvy people are well-aware of the large number of PDFs that have searchable text, when downloaded as eBooks, software manuals from major corporations, and other "professional" sources, and frustratedly aware also that their own home-generated PDFs are not searchable in such a manner. I'd be very surprised if a large proportion of readers of this article aren't here looking for an explanation. — SMcCandlish Talk⇒ ʕ(Õلō Contribs. 01:45, 23 November 2011 (UTC)

Postscript and transparency

Ghostscript can handle transparency in PostScript documents. As I understand it, they have implemented the feature because Adobe Distiller support it (or rather enabled it: that is, introduced the syntax for transparent vector graphics into PostScript and enabled support for transparency in bitmap images, since Ghostscript already had support for transparency when rendering PDF-files).

So, just like PDF, at least some versions of PostScript (as implemented by not to ancient versions of GhostScript and Adobe Distiller) do support transparency. -- (talk) 11:49, 27 September 2011 (UTC)

Why call it "Portable" Document Format?

This is a wonder119.85.246.160 (talk) 00:01, 3 October 2011 (UTC)

I guess cause it is a Portable Document Format. — Preceding unsigned comment added by (talk) 16:06, 3 October 2011 (UTC)

Because the creators of PDF go to great lengths to make it possible for different people to view and print PDF files and see the same thing using different types of computers and different operating software.
This is not true of many file formats. Just for example, some versions of Microsoft Word create files that cannot be understood by other versions of Microsoft Word. This is not to pick on Microsoft Word, which is an amazing program IMO, but just to illustrate what is meant by saying that a PDF file is "portable".
Wanderer57 (talk) 16:13, 4 October 2011 (UTC)
In this case "portable" expresses the hope that PDF will be nearly "universal", usable and viewable on nearly every computer -- and look pretty much the same.- (talk) 14:06, 4 March 2013 (UTC)


I am surprised at the minimal mention of problems with PDF files most of which seem to come from a user's or application's misuse of the format, as is frequently the case with a "it can do anything" tool. While some PDF documents are excellent for printing most are horrible for viewing on a display. The format is hardly portable when it does not provide for presentation on device or even a windowed display which is not the same configuration as the author used. Many scanners/faxes create PDFs which are simply graphic images which would be much better represented by a graphic format like PNG. Even documents that are truly text are frequently generated with non-functional table of contents and pagination reflecting the author's original layout rather than the viewer's making navagation and simple scrolling impossible. The storage requirements for nearly PDF documents is extravagant to say the least. (Bring it on.) DG12 (talk) 19:48, 23 January 2012 (UTC)

I would also like to see a discussion of the limitations of PDF. On many computers I've used (in Korea), PDF crashed the system of simply would not down-load. Kdammers (talk) 03:47, 24 November 2012 (UTC)

Recent versions not fully compatible with Windows XP

Recent versions of Adobe Acrobat are not fully compatible with Windows XP. Printing is particularily problematic. Characters are displaced by one ASCII code value!

PDF Exchange Viewer is a freeware that is fully compatible with Windows XP, Vista and 7. Printing using PDF Exchange Viewer is perfect.

Adobe must surely be aware of the problem but don't appear to want to fix it. As XP is still the most used operating system in the world (just), such an attitude reflects badly on the company. — Preceding unsigned comment added by (talk) 14:21, 24 January 2012 (UTC)

This article is about the file format, not about software by Adobe.--Oneiros (talk) 17:24, 24 January 2012 (UTC)

Merge GNU PDF into Portable_Document_Format#Implementations

In lieu of prod, the GNU PDF article should merge into the section Portable_Document_Format#Implementations (talk) 09:34, 17 May 2012 (UTC)

Agree--Oneiros (talk) 22:36, 17 May 2012 (UTC)


I understand that there are limitations regarding what kind of editing 3rd party vendors can provide with respect to .pdf documents, because of patents held by ADOBE. Can someone list those patents and when they expire? — Preceding unsigned comment added by Skysong263 (talkcontribs) 19:27, 25 June 2012 (UTC)

More information on the security encryption

This page:

Lists the different encryption algos, key lengths, and encodings for the various PDF spec levels. I do not believe the information is copyrighted (since it is simple factual knowledge) and would be a useful addition to the PDF wiki page.

PDF 1.1 - 1.3 (Acrobat 2-4)
RC4 40-bit
32 characters (Latin-1)

PDF 1.4 (Acrobat 5)
RC4 128-bit
32 characters (Latin-1)

PDF 1.5 (Acrobat 6)
same as PDF 1.4, but different application of encryption method
32 characters (Latin-1)

PDF 1.6 (Acrobat 7) and PDF 1.7 = ISO 32000-1 (Acrobat 8)
32 characters (Latin-1)

PDF 1.7 Adobe Extension Level 3 (Acrobat 9)
AES-256 with weakness in password handling
127 UTF-8 bytes (Unicode)

PDF 1.7 Adobe Extension Level 8 (Acrobat X) PDF 2.0 = ISO32000-2
AES-256, but different password handling
127 UTF-8 bytes (Unicode) — Preceding unsigned comment added by (talk) 07:22, 28 June 2012 (UTC)


I realize that this article has gotten good ratings on clarity, but I think the raters are mostly computer-savvy people. In fact, to me, the first sentence is too opaque. To see a better opener, go to the simple-English article.Kdammers (talk) 03:54, 24 November 2012 (UTC)