While 4k+ screens and projectors enable even more precision in current display technologies, a band of media artists believe there remains untapped aesthetic possibilities to draw out of older media (which was all new at one time). One technology in particular, the Cathode Ray Tube (CRT), long since replaced in the realm of TV and computing by flat panel technology (LCD, LED, OLED), is being rediscovered for its unique analog display properties. The CRT started with an instrument that physicist Ferdinand Braun developed for visualizing alternating current. He published the resulting setup in 1897: an evacuated tube with a diaphragm for focusing the electron beam and a phosphor screen for allowing him to see the movements of the resulting light spot. Braun actively controlled the electron beam – thus one may speak of electronics – by applying magnetic forces.
These first electronic images produced by the CRT were diagnosis and test images, but by the 1930s, electronic image transmission (TV) on both the sending and receiving end was possible. For TV, images are being dissected into halves and arranged in lines according to standards, e.g. NTSC. For testing equipment and measuring voltages on the other hand, basic vector images suffice. The oscilloscope, a piece of testing equipment that resulted out of Ferdinand Braun’s setup, displays changes in voltage dynamically on its glowing screen, for example plotted against time. Amongst the many applications in electrical engineering, the necessary measurements to be done in a sound studio may serve as an example: the oscilloscope is a common tool for the audio engineer, especially since the 1950s experiments in electronic music.
XYscope is a new library for the open source programming platform Processing (a framework based on Java, enabling artist and designers for creative-coding), allows the rendering of vector graphics on a vector display (oscilloscope in X-Y mode, laser etc). It began as a series of pseudo-library functions for redrawing primitive shapes (point, line, rectangle, ellipse, complex shapes) on an 80's pen-plotter, which was brought into the classroom while teaching data-visualization in a physical way. As the pen overlaps a region of the paper, the layer and density of ink grows, something that a flattened image sent to a laser printer wouldn't reveal.
From there, the functions were extended for another seminar that introduced a programmable RGB laser combined with video projection for exploring audio visualizations with uniquely combined light sources.
All of these custom functions deconstruct the built-in functions for drawing the same primitives, but convert their outputs to an X-Y list of coordinates that translated nicely to their desired output medium.
For these previous media, standardized programming languages had been developed (HPGL for pen plotters, ILDA for lasers). When it comes to drawing on the oscilloscope, there is no standard yet, as it requires the translation of an image to audio (custom waveform oscillators) in stereo. This translation step to stereo sound is necessary, as the left and right channels of sound are plugged into the oscilloscope's two channel inputs which, when set to X-Y mode, represent the horizontal and vertical movement of the electron beam. Thus an image is turned into audio to be turned back into an image on the final display.
When voltage is not plotted against time on the oscilloscope screen, but against another voltage source, a closed curve occurs. Already in his seminal paper of 1897, Ferdinand Braun discussed these Lissajous curves which are named after another physicist who, earlier in the 19th century, worked on the frequency relationships between oscillations.
In the early 1950s, artists and filmmakers, such as Mary Ellen Bute, Hy Hirsh or Norman McLaren, started to incorporate these electronic images of harmonic phase relationships into their work. Filming the screen of an oscilloscope, Mary Ellen Bute explored the potential of electronics for her colorful Visual Music-films. It is remarkable, how early these artistic experiments with electronic imagery were, compared to the establishment of electronic arts since the 1960s.
Exploring Lissajous figures nowadays is still appealing, as harmonic phase relationships offer a rich visual vocabulary. However, moving beyond Lissajous patterns proved to be much more difficult, as it requires drawing custom irregular waveforms that represent the beam’s timed movement in the horizontal and vertical axis. While there had been very impressive examples over the recent years in this domain (Youscope demoscene, Quake on oscilloscope, OscilloscopeMusic among many more), few broke down the exact process of translation for image to audio, let alone open sourced code.
In the design realm, Just Van Rossum had made big steps in this process as explained in his ATypi talk of 2016, in which he explored the sound of type design by rendering letterforms on the oscilloscope via audio translation. It was in discussion with Just that the missteps in previous attempts to draw on the oscilloscope became clear. This quickly opened the gate for exploring any vector based graphic on the oscilloscope, providing its glowing green line of infinite resolution.
Again, the primitive shape functions previously mentioned were repurposed for this unique output, being copied and pasted between multiple sketches, as it became clear that the code base needed to become a proper library for easy maintenance and sharing. The Processing environment thrives on the contributions from the community for a wide range of specific tasks, from physics simulation, to rendering and exporting type, to (in this case most relevant) audio analysis and synthesis. Due to the open source and free community that enabled this exploration, it was important to provide the same in return. This library automatically converts any drawn forms into the complex stereo waveforms required to send as audio to the oscilloscope for display. In the end, this produces a true 'what you see is what you hear'. Beyond the A/V possibilities that enables, the library is as rich as one’s own creative-coding abilities.
Out of the box, XYscope includes examples for free drawing, basic shapes, typography and combining interactive sensors (webcam, Kinect depth cam). By removing the restriction of a pixel grid, forms can be designed and displayed in ways that our laptop workstations don't allow. By multiplying or combining these signals with additional inputs (audio for example) or manipulating them en-route, surprising forms will be discovered for creative use. As with any analog signal, imperfections and variances will occur in transmission, which can offer both a liveliness to the output, as well as artifacts for exploration.
LINKS:
XYscope, Processing library for oscilloscope
http://teddavis.org/xyscope
https://vimeo.com/226597331
https://github.com/ffd8/xyscope
https://www.instagram.com/teddavisdotorg/
Just Van Rossum ATypi Talk, The Sound of Shapes & Shape of Sounds
https://www.youtube.com/watch?v=1y1w5dvT5-I
Youscope (oscilloscope demo)
https://www.youtube.com/watch?v=s1eNjUgaB-g
Quake on Oscilloscope
http://www.lofibucket.com/articles/oscilloscope_quake.html
OSCILLOSCOPE MUSIC
http://oscilloscopemusic.com