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Articles by Peter Wyatt
A case study in PDF forensics: The Epstein PDFs
We report on the technical aspects of the PDF files released by the US Department of Justice in connection with the Epstein Files Transparency Act. December 22, 2025 A case study in PDF forensics: The Epstein PDFs We report on the technical aspects of the PDF files released by the US Department of Justice in connection with the Epstein Files Transparency Act.
Future-proofing XMP identification schema
September 26, 2025 ISO standardized subsets of PDF, such as PDF/UA, enable files to claim conformance to a specific version of PDF/UA using XMP-based PDF/UA identification metadata. As a result of changes in ISO policy the defined XMP field names have evolved. About Peter Wyatt A developer and researcher working on PDF technologies for more than 20 years, Peter is the PDF Association’s CTO and an independent technology consultant.
Google’s PDF preview fails, including with PDFs made by Google Docs!
July 30, 2025 We were asked to investigate non-functional internal document (intra-document) hyperlinks in PDFs stored on Google Drive and viewed with Google’s Preview. Here’s what we found. About Peter Wyatt A developer and researcher working on PDF technologies for more than 20 years, Peter is the PDF Association’s CTO and an independent technology consultant. For files hosted on Google Drive, Google provides a convenient viewer sometimes referred to as “Google’s Preview” or the “Google Viewer”.
Continuously Scrollable Comics: ISO ad hoc report analyzes related standards
Continuously Scrollable Comics: ISO ad hoc report analyzes related standards July 2, 2025 This recently published report from ISO/IEC JTC 1 SC 34 presents an analysis of related standards, the current status and size of the CSC industry, the cultural importance of continuously scrollable comics, and various technical challenges. About PDF Association staff The PDF Association staff delivers a vendor-neutral platform in service of PDF’s stakeholders.
Brotli compression coming to PDF
Brotli compression is coming soon to PDF 2.0, enabling smaller file sizes. Sample PDF files are available to kickstart development! About the author: Long-time PDF developer. Works on Ghostscript and MuPDF. Background The PDF format is over 30 years old. All things considered, it’s standing up pretty well. Of course, technology has advanced massively since those early days. Today, the PDF community is working to incorporate some of those advancements into the PDF world.
Jpegli works in PDF
Google’s Jpegli promises smaller JPEG images (and so, smaller PDF files) with no change to reader software! Check it out for yourself! About the author: Peter Wyatt is the PDF Association’s CTO and an independent technology consultant with deep file format and parsing expertise. A developer and researcher working on PDF technologies for more than … Read more Jpegli is a relatively new open-source JPEG library created by Google.
The smallest possible (valid) PDF
What’s the smallest possible fully compliant and validate-able PDF file? We set out to answer the question. About the author: Peter Wyatt is the PDF Association’s CTO and an independent technology consultant with deep file format and parsing expertise. A developer and researcher working on PDF technologies for more than … Read more Over the years we’ve seen various challenges to create the smallest possible valid PDF file.
PDF Differences - one year later
In 2021, not a single tested implementation passed this test. 3 years later about three-quarters of viewers tested now render the test case correctly. About the author: Peter Wyatt is the PDF Association’s CTO and an independent technology consultant with deep file format and parsing expertise. A developer and researcher working on PDF technologies for more than … Read more Repeatable, reliable rendering and functionality are at the very heart of PDF’s value to users.
PDF-UX: Page Labels
Does your PDF viewer fully support page labels? Does your PDF authoring software? Support for page labels can be a key factor in choosing a PDF viewer, especially for users dealing with complex documents. About the author: Peter Wyatt is the PDF Association’s CTO and an independent technology consultant with deep file format and parsing expertise.
Don’t risk losing users’ trust: future-proof your PDF implementations
As the members of PDF’s technical community continue their work on defining a future version of PDF, with potentially large changes to core PDF (via the Imaging Model Technical Working Group), it is important to consider the impact of these changes on today’s software, and how implementers can best support end users. As an industry, we should be concerned about how we might confuse end users when they try to use future PDF files.
PDF Fragment Identifiers
Peter Wyatt latest article focuses on improving the user experience for website visitors needing to access specific content in longer PDF documents. About the author: Peter Wyatt is the PDF Association’s CTO and an independent technology consultant with deep file format and parsing expertise. A developer and researcher working on PDF technologies for more than … Read more This article is for web designers, content creators, webmasters, and web browser developers.
(S)-1-Methyl-2-oxoimidazolidine-4-carboxylic Acid
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Preparing for PDF files “from the future”
These synthetic files are intended for user experience and human-computer interaction (HCI) specialists to assess the behavior of their current generation of PDF applications to ensure that appropriate user-centric messages are displayed before future PDF changes are made and available to users. About the author: Peter Wyatt is the PDF Association’s CTO and an independent technology consultant with deep file format and parsing expertise.
How to read ISO publications about PDF
All ISO publications are written according to a set of rules known as the ISO Directives. In this article, the PDF Association’s CTO, Peter Wyatt explains how to understand the formal terminology in ISO’s standards for PDF technology. About the author: Peter Wyatt is the PDF Association’s CTO and an independent technology consultant with deep file format and parsing expertise.
PDF versions - PDF Association
How meaningful is PDF’s version number? SafeDocs’ research reveals that 20% of extant files contain features that exceed the stated version! About the author: Peter Wyatt is the PDF Association’s CTO and an independent technology consultant with deep file format and parsing expertise.
Discovering PDF metadata
Peter Wyatt shares his custom metadata panels – very useful for discovering ISO standards and PDF Declarations metadata! (until vendors catch up!) About the author: Peter Wyatt is the PDF Association’s CTO and an independent technology consultant with deep file format and parsing expertise.
Orientational order/disorder and network flexibility in deuterated methylammonium lead iodide perovskite by neutron total scattering
Orientational order/disorder and network flexibility in deuterated methylammonium lead iodide perovskite by neutron total scattering† The phase transitions and orientational order of the methylammonium molecular ion in a deuterated sample of [CH3NH3]PbI3 have been studied using neutron total scattering and Reverse Monte Carlo methods.
A Direct Analysis of β-N-methylamino-l-alanine Enantiomers and Isomers and Its Application to Cyanobacteria and Marine Mollusks
1. Introduction Cyanobacteria are well known for producing a wide array of toxic compounds, both with acute and chronic toxicities [1,2]. With fossils dating back up to 3.6 billion years [3,4,5,6,7], these organisms are considered to have had a large influence on the evolution of our planet, such as through the generation of the oxygen atmosphere and the Great Oxidation Event [8,9,10,11].
Parsing PDF’s dialects
As a follow-on to my previous article on Perfecting PDF Lexical Analysis, this article discusses the importance of correctly parsing the “dialects” of PDF to ensure compliance with the PDF specification, and thus compatibility and interoperability between implementations. Just like the English dictionary definition, a “dialect” when parsing “is a (relatively small) variation or extension of the language that does not change its intrinsic nature” ().
“PDF Differences” GitHub repository is now public
Overview As announced on May 13, PDF developers everywhere have a new resource; targeted test cases highlighting differences between implementations, including in-depth technical explanations. The first set of such “parser differential” test-cases became public on September 22, 2023, allowing the full PDF ecosystem - PDF Association members and non-members alike - to align.
PDF malformations and more
Funky PDF != malformed PDF The image posted in this tweet caught our attention. When we traced through to the source it was captioned as “It’s particularly useful for malformed PDF files, like this example with PDFUnknown structures”. But is this PDF really malformed? Is that yellow or orange highlight supposed to be the malforms? Obviously PDF version 1.8 is unexpected (as no specification of that name has ever existed!), but the file is otherwise entirely syntactically valid.
“Cheat Sheets” for PDF, for free!
Not all developers who use PDF spend their working lives in the depths of the PDF specification. To help developers whose relationship with PDF’s specification is more casual (or tangential), the PDF Association is publishing four free PDF “cheat sheets” as an aid in remembering key terms and concepts, without constantly referring to ISO 32000 itself. Cheat sheets don’t introduce PDF technology, and are no substitute for an initial learning phase.
How to get started with PDF 2.0
PDF 2.0 (available at no cost from the PDF Association) introduced several new features and technical capabilities which might appear daunting at first read. eter PDF has never required implementation of every feature of every PDF version.
“PDF Differences” available to members; public access begins Sept. 22
Peter Wyatt Peter Wyatt is the PDF Association’s CTO and an independent technology consultant with deep file format and parsing expertise. A developer and researcher working on PDF technologies for more than 20 years, he is ISO Project Leader of ISO 32000 (the core PDF standard), co-Chairs the PDF Association’s PDF TWG and is the PDF Association’s Principal Scientist leading the organization’s …
Arlington PDF Model
The Arlington PDF Model is a free and open-source machine-readable data model of all PDF objects available via GitHub. It is directly derived from the latest PDF 2.0 specification ISO 32000-2:2020 and its related resolved errata. and thus is entirely vendor- and implementation neutral.
New large-scale PDF corpus now publicly available
The SafeDocs corpus, “CC-MAIN-2021-31-PDF-UNTRUNCATED”, is now publicly available via the Digital Corpora project website: https://digitalcorpora.org/corpora/file-corpora/cc-main-2021-31-pdf-untruncated/. This new corpus - nearly 8 million PDFs totaling about 8 TB - was gathered from across the web in July/August of 2021.
ISO/TS 24064
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Australia and New Zealand jointly adopt PDF/A-4
The joint Australian and New Zealand IT-021 mirror committee on Records and Document Management Systems recommendation to both Standards Australia and Standards New Zealand, the national standards bodies of the respective countries, to adopt PDF/A-4 was recently completed on 23 December 2022.
Australia and New Zealand jointly adopt PDF/A-4
National mirror committees are composed of experts and end user representatives to provide national perspectives into both ISO standards as well as local standards activities. These committees “mirror” the activities of one or more ISO committees to provide national perspectives, comments and feedback, and ballot positions on draft ISO publications as well as guidance to their own national standards body on local activities.
CMap Resource Updates for Unicode 15.0
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PDF 2.0 and ISO 19445 XMP metadata for image and document proofing
This article provides recommendations to industry as to how ISO 19445 might be used with PDF 2.0 and related technology updates relevant to the graphic arts industry.
20 years of transparency in PDF
The end of 2021 marks the 20th anniversary since the Adobe PDF 1.4 specification introduced partial transparency into mainstream page description languages. The transparent imaging model extended “... the opaque imaging model of earlier versions [of PDF] to include the ability "...to paint objects with varying degrees of opacity, allowing previously painted objects to show through”.
Prolonged and efficient near-infrared photoluminescence of a sensitized organic ytterbium-containing molecular composite.
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A Pioneering Spirit: My Family's Coming to Canada Story
I am an avid reader with a particular interest in writings about Canada.
Recently identified PDF digital signature vulnerabilities
On February 25, 2019, researchers from Ruhr University Bochum and Hackmanit GmbH published pdf-insecurity.org, a detailed explanation of several vulnerabilities they had identified in PDF viewers and online validation services relevant to signature validation in digitally-signed PDF documents. The vulnerabilities are pertinent only to such digitally-signed documents, and not to PDF in general.
Continuous Tuning of Organic Phosphorescence by Diluting Triplet Diffusion at the Molecular Level
Organic long-persistent phosphorescent materials are advantageous due to the cost-effectiveness and easy processability. The organic phosphorescence is achieved by the long-lived triplet excitons, and the challenges are recognized regarding the various nonradiative pathways to quench the emission lifetime. Taming long-lived phosphorescence is generally engaged with the charge-transfer or exciton diffusion in molecular stacking to stabilize triplet excitons or form a photoinduced ionized state.
Apple Updates Its Event App Guidelines In Time for the New Year | CadmiumCD
In June 2017 Apple made a surprising change to one of their app review guidelines (4.2.6). This forced event app vendors to each develop a single “Container App” solution in which all their clients’ event apps could be accessed through a single app in the App Store. We learned from Apple this past summer that this sudden change would be delayed until the beginning of 2018.
Apple Review Guideline Changes Affect Event App Vendors
This article was written by, Peter Wyatt, CTO and Co-Founder of CadmiumCD In June, Apple changed their app review guidelines, and has started rejecting some of the conference apps that event app vendors are publishing to the app store. We learned from Apple that an existing rule (rule 4.3) in their review process was now being strictly enforced. Apple wants to substantially lower the number of apps in the app store, and they are now targeting apps produced by event app vendors.
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