Dr. Lex' Informative Section

This page contains some topics that could be classified as “educative”. Sometimes I notice many people do not know much about a certain topic, or have wrong ideas about it. Or, people ask me the same questions over and over. I will then try to point them to a good webpage that explains the topic. Obviously if there is no such webpage, my only option is to write it myself. This has resulted in the following collection of articles. Most of these topics are related to the internet and multimedia.

For information specific to 3D printing, there is a separate section in this site.

For very small articles or short notes I have created a blog as well. Often I will also create a short post to announce an article, feel free to use those announcement posts to comment on the article.

Internet-related TopicsMultimedia-related TopicsPublicationsVarious

Internet-related Topics

  • Web PushThe Sorry State of Implementing Web Push Messages in 2024
    In this article, I report my experiences gathered while trying to implement arguably the simplest possible use case for Web Push notifications using Google's FCM.
  • Refer(r)erA Plea to Preserve Meaningful Referrer Headers
    This article tries to give some sensible guidelines for choosing how a website should treat referrer headers. Please don't just blindly follow some default pushed forward by a big company.
  • Top 13 things 2020Top 13 Things Not to Do When Designing a Website
    The title says it all. If you plan on making/are making/have made a website (and I mean a true website, not some kind of app thing that also happens to be available in regular browsers), you should read this and see to what degree your visitors will be/are being/have been annoyed by flaws in your design. I now tend to make a new version of this article about every 3 years, the current one is from 2023.
  • Web GraphicsWeb Graphics and Animations
    How to choose between graphic formats for webpages and how to make animated GIFs, make 'em look better and optimize them so that they load faster.
  • SPAMAnti-Spam information
    Tips to avoid receiving “spam” mail, and how to fight it if you're already being spammed.
  • iTunes songsAnother Reason Not to Buy DRM-Protected iTunes Songs
    Of course, the main reason not to buy something that has DRM, is DRM itself. But this (now obsolete) page explains why the ‘standard’ 128kbps iTunes songs (i.e. non-‘iTunes Plus’) were to be avoided from a quality point of view as well.

Multimedia-related Topics

  • Volume controlsProgramming volume controls
    This text explains why the volume controls in a lot of software applications are a pain in the ass to work with, and how to implement a good volume control. Also a short part about frequency controls and analysis. A must-read for audio programmers!
  • DecibelPlease Stop Displaying Your Lack of Understanding of the Decibel Scale
    A companion article with the above, this explains the decibel scale for measuring sound pressure level in more detail, as well as how people often misinterpret it and make ludicrous statements about loudness.
  • Bitrate calculatorVideo Bitrate Calculator
    This calculator can be helpful to determine what bitrates to use when encoding video files.
  • Encoding tipsTips for Encoding Videos
    A buch of short hints on how to make good conversions of existing videos, with a specific focus on how to do it in HandBrake.
  • HDR PhotosMaking HDR Photos with Luminance HDR
    This is a short explanation of how it is possible to obtain very neat-looking high dynamic range photos from even a relatively cheap compact camera.
  • UHDJust how useful is UHDTV, aka 4K or 8K?
    Another digital cinema conundrum: should you upgrade your television or projector to 4K resolution, or even 8K? You may want to read this article before you start spending your hard-earned money.
  • Media formatsMedia Formats Explained
    This page attempts to shed some light on the difference between multimedia formats, codecs, media players, … because many people appear to have trouble differentiating between these concepts.
  • 3D FailWhy ‘3D’ Will Fail… Again
    By the time you're reading this, the general public may already be scoffing at the ‘3D’ hype that started around the year 2009, or has forgotten about it entirely. This text explains why, and why I believe there will likely never be perfect 3D cinema.
  • Loudness WarsWhy aren't All Songs Recorded at the Same Loudness and What is Wrong With Music Nowadays?
    This text explains why music has steadily become more annoying to listen to since 1990, due to a phenomenon commonly called the “Loudness Wars”.
  • Micro game reviewsMicro Game Reviews
    These are some very short reviews of some of my all-time favourite computer games. Most of these games are pretty old now but perhaps these reviews will convince the reader to stop trying to chase the latest stupid trends for a while, and instead revisit a golden oldie from a while ago.
  • Movie ratingsHow I Rate Movies
    This is actually just a cheat sheet for myself to remind me how to decide what score I should give when rating a movie on IMDb's 10-star scale. But it would of course be nice if everyone would use the same rating scale.
  • QTVR mathHow does a QTVR panorama work?
    Basic + more detailed information about the aspects behind (cylindrical) QTVR panoramas.
  • Make QTVR panoHow to make a QTVR panorama
    A step-by-step manual on how to create a panorama yourself. The information about software is dated, but the general principles are still applicable.
  • Make QTVR objectHow to make a QTVR object
    A step-by-step manual on how to create a QTVR object yourself. Again, software info has become rather obsolete.
  • QTVRQTVR Panoramas
    Some QuickTime VR Panoramas I made, from various subjects like real-world scenes, synthetic graphics and computer games.


  • PhDAcademic Publications
    These are the publications I made during my academic career between 2002 and 2009. Most of them are about object category recognition.


  • Bits and bytesDigital Information Sizes Calculator
    A calculator which converts between SI units for file sizes (e.g. kilobytes) and IEC units (e.g. kibibytes), plus an explanation of the difference between them.
  • TimeSimple Time Calculator
    Add or subtract time values.
  • Euro calculatorEuro Exchange Calculator
    A simple calculator which converts between the 12 obsolete currencies whose rate relative to the Euro has been fixed.
  • dtWerkwoorden Vervoegen
    (Dutch only). Deze pagina probeert op een duidelijke manier uit te leggen hoe werkwoorden te vervoegen in het Nederlands en de beruchte ‘dt-fouten’ te vermijden.
  • PunctuationBasic Punctuation
    I could only receive that many e-mails with horrible punctuation before I was no longer able to resist the urge to write this page, so here it is. Five simple rules than can turn an uninviting lump of text into something that will not immediately scare away potential readers.