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==== CTXz ====

{{template>infobox|
name=Patrick Pedersen|
nick=ctxz|
email=ctx.xda@gmail.com|
phone=+420 607 952 628|
web=[[https://github.com/CTXz user:ctxz]]|
photo=ctxz.png?200|
irc=ctxz
}}

Hello kind reader, thank you for visiting my profile page!

==== About me ====

I'm currently a computer engineering student at the Technical University in Berlin and my interest lie mostly in areas where computer science and electrical engineering overlap, such as low-level programming (kernel stuff, firmware programming, assembly programming) and digital, as well as analog electronics design. I also have my fair share of interest in ancient electronics, or generally, old technology, mostly due to their hackable nature. I also find interest in art and while I do lack the skills to make traditional art, I have been making [[https://en.wikipedia.org/wiki/Glitch_art | "glitch art" ]] by applying my technical skills, either digitally by using photo manipulation software such as gimp and/or by writing software to manipulate/corrupt image and video data, as well as analogously by designing circuits that tamper with video signals.

==== Public Projects ====

My GitHub Profile: https://github.com/CTXz


=== Android ROM Porting ===

I've been part of numerous open source projects, starting all the way back to 2015 where I started out with Android ROM porting, where I would port TWRP and CyanogenMod (currently known as LineageOS) to various devices. Some notable ports were:

  * [[https://forum.xda-developers.com/galaxy-s5-mini/development/g800f-m-y-lineageos-14-1-g800f-m-y-t3549055 | LineageOS 14.1 co-dev for the Samsung Galaxy S5 Mini]]
  * [[https://forum.xda-developers.com/z5-compact/development/rom-cyanogenmod-13-sony-xperia-z5c-t3339930 | CyanogenMod 13 for the Xperia Z5 Compact E5823/E5803]]
  * [[https://forum.xda-developers.com/tab-4/development/rom-cyanogenmod-13-galaxy-tab-4-lte-t3324627 | CyanogenMod 13 for the Samsung Galaxy Tab 4 T235]]
  * [[https://forum.xda-developers.com/tab-s2/development/rom-cyanogenmod-12-1-tab-s2-8-0-t3268767 | CyanogenMod 12 for the Samsung Galaxy Tab S2 T710]]

I have since moved away from the Android Porting community and progressed more towards microcontroller programming, low-level assembler programming (also for the sake of being able to reverse engineer software) and electrical engineering, mostly because I became sick of having to stick to a massive code base that I have so little control over.

=== reHackable ===

More recently I've become a co-administrator of the [[https://github.com/reHackable | reHackable GitHub organisation]], which revolves around community support and the tinkering/hacking of reMarkable e-paper tablets. There I maintain mostly two repositories:

  * [[https://github.com/reHackable/scripts | reHackable scripts]]
  * [[https://github.com/reHackable/awesome-reMarkable | The reMarkable Awesome List]]

I am also an contributor at the [[https://remarkablewiki.com/|reMarkable wiki]] as well as the owner of the [[https://discord.gg/JSSGnFY | Community Discord Chat Server]].

=== Glitch Art ===

As I began to further dig down the pathway of low level programming, my curiosity to understand how computers, let alone most electronics that house a microcontroller, work rose. I desired answers to the many questions that I had, such as how memory worked on a physical level, how microcontrollers communicate with other devices and how a CPU could translate those magical opcodes into instructions. I felt that I lacked the necessary knowledge in electronics, or electrical engineering in general, and thus decided to invest more of my time into understanding electronics.

Simultaneously, I had also discovered Glitch Art, which is a genre of art that uses digital or analog errors for the purpose of making aesthetics. We see glitch art being used in popular culture very often. Here are a few examples:

  * [[https://youtu.be/qCjSApp2o1E?t=63 | Spider-Man: Into the Spider-Verse (2018) - Doc Ock Scene]]

In this scene, a "glitch-alike" effect is used that is supposed to represent "glitching" often occurring in video games and videos in general. I say "glitch-alike" as this clearly did not involve actual errors, but has rather been made to appear alike glitches that occur due to errors. 

  * [[https://youtu.be/tt7gP_IW-1w?t=50 | A$AP Mob - Yamborghini High ]]

The music video of A$AP Mob's "Yamborghini High" song makes heavy use of what glitch artists call //datamoshing//. Datamoshing is a form of digital glitch art that induces errors, and thus glitch artifacts, by exploiting video compression. You can find a more detailed explanation on the [[https://en.wikipedia.org/wiki/Compression_artifact#Artistic_use | Wikipedia "Compression artifacts" page here]]. These errors will be well familiar to those that have a slow internet- or poor TV connection, as video streaming across these mediums typically make use of video compression.

Initially I began publishing digital glitch art under a Instagram account that goes by the name of [[https://www.instagram.com/video.home.systems/ | Video Home Systems]], mostly with GIMP along with the G'MIC plugin, which offers multiple effects for image distortion. As I began to read more about electronics however, I began to expand more in the area of analog glitch art. Analog glitch art uses physical means, such as circuitry for video signal manipulation, to establish glitch artifacts. A simple example of analog glitch can easily be achieved with a VHS recorder and a magnet. By applying a magnetic field across the VHS drum tapes, the signal transmission from the VHS tape to the VHS recorder is altered. As a result, interesting artifacts can be observed. Note that the magnet will also likely erase or corrupt the VHS tape, which will further lead to interesting artifacts.

In a way, analog glitch art became somewhat of a playground for me to test out and further develop my understanding of electronics. As of now I have been working on two analog glitch projects, although the first one makes use of microcontrollers.

== OptoGlitch ==

OptoGlitch Is An Optocoupler Built For Distortion. It works by analogously parsing each pixel of an Image trough a optocoupler circuit consisting of a LED and a photo resistor. The RGB values are translated into brightness values of the LED. Since the photo-resistor input resolution is rather low, allot of data is lost in the process of transmission. In addition to that, the circuit is left out exposed, meaning outer changes in light will also affect the parsing process. Finally, some very interesting "wavy" artifacts can be observed, which turn out to be a result of the fact that ATmega PWM timers run asynchronously to the program code that is being executed.

The Hackaday blog has written a nice article about this project [[https://hackaday.com/2019/02/20/optoglitch-is-an-optocoupler-built-for-distortion/ | here]].

The rather primitive circuitry and software has been well documented over at the projects [[https://github.com/CTXz/OptoGlitch  |GitHub repo]]. I've also written [[https://docs.google.com/document/d/1IXgLr-epezUETSYK8bRIUSsdWn0loQHT_kls9pORURU/edit?usp=sharing | a paper where I fully analyze the OptoGlitch with a oscilloscope]].


Pre-parse(left) vs Post-Parse(Right)

{{:user:preparse.png?direct&400|}}{{:user:postparse.png?direct&400|}}

== Video Glitch Array ==

Video Glitch Array is a project in which I attempt to create glitch art explicitly by manipulating VGA signals. I achieved this by building my very own circuitry that tampers with VGA color- and clock signals. By the end of this project, I hope to document it on this wiki and create a glitch art PCB that features all methods of VGA glitching that I have explored and developed through out the project.

{{:user:img_20190822_214826.jpg?600|}}