A while ago, I wanted to analyse the difference of some PDF documents: why they had suddenly grown to twice their size.
[WayBack] Jeroen Pluimers en Twitter: “dat genereren kun je overigens zien als je dezelfde downloads doet, maar dan een fikse periode uit elkaar.…”
There are quite a few tools on [WayBack] Browse Internal PDF Structure – Super User and [WayBack] Best tool for inspecting PDF files? – Stack Overflow, including:
- [WayBack] PDF Object Browser (JavaScript based)
- [WayBack] GitHub – itext/rups: RUPS is an abbreviation for Reading and Updating PDF Syntax. RUPS is a tool built on top of iText® that allows you to look inside a PDF document and browse the different PDF objects and content streams. depending on [WayBack] GitHub – itext/itext7: iText 7 Community
- [WayBack] GitHub – Rossi1337/pdf_vole: PDF Debugger (Java based)
- [WayBack] PDF Document Inspector (on MacOS)
They also made me discover [WayBack] GitHub – pipwerks/PDFObject: A lightweight JavaScript utility for dynamically embedding PDFs in HTML documents documented at [WayBack] PDFObject: A JavaScript utility for embedding PDFs 
This particular case
The quickest way to analyse these for me was [WayBack] PDF Object Browser based on [WayBack] GitHub – brendandahl/pdf.js.utils: PDF.js Utility Files which is also the foundation of [WayBack] Test PDF Creator.
It runs in your web browser as local JavaScript, so it is pretty OK to load a PDF file into it: it does no “phone home”.
In this case, for generating PDF files with the same content, ABN AMRO added five Type 3 fonts of which one font was not used at all, and two others used to be Type 1 fonts.
Type 1 (also known as PostScript, PostScript Type 1, PS1, T1or Adobe Type 1) is the font format for single-byte digital fonts for use with Adobe Type Manager software and with PostScript printers. It can support font hinting.
It was originally a proprietary specification, but Adobe released the specification to third-party font manufacturers provided that all Type 1 fonts adhere to it.
Type 1 fonts are natively supported in Mac OS X, and in Windows 2000 and later via the GDI API.[2] (They are not supported in the Windows GDI+, WPF or DirectWrite APIs.)
Type 3 font (also known as PostScript Type 3 or PS3, T3 or Adobe Type 3) consists of glyphs defined using the full PostScript language, rather than just a subset. Because of this, a Type 3 font can do some things that Type 1 fonts cannot do, such as specify shading, color, and fill patterns. However, it does not support hinting. Adobe Type Manager did not support Type 3 fonts, and they are not supported as native WYSIWYG fonts on any version of Mac OS or Windows.
So far for optimised PDF rendering…
Being in software development for this long, I am constantly reminded that The inmates are running the asylum – Wikipedia. I can definitely recommend reading “The Inmates Are Running the Asylum: Why High Tech Products Drive Us Crazy and How to Restore the Sanity”, by Alan Cooper:
–jeroen
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