Computational Thinking

Joel Gethin Lewis

Lecture 4: Compressing

What I'm going to talk about now:

0. Review where we are in the lectures.
1. Moving to four dimensions.
2. Artists working with the space and time.
3. Text compression.
4. Spatial compression and Temporal compression.
5. The Fast Fourier Transform.
6. Bonus: three kinds of feedback: audio, visual and interactive.

1. Moving to four dimensions.

• Going from Cube to Hypercube.
• You can also go from the Sphere to the Hypersphere.
• You can also think of Time as the fourth dimension.
• You can use any variable as a new dimension, and measure distance between them using Pythagoras, as we saw in the previous article.
• Perfect Shapes in Higher Dimensions from Numberphile, which is a great channel to get lost in.

2. Artists working with the space and time.

• Eadweard Muybridge, Sallie Gardner at a Gallop.
• Étienne-Jules Marey and the photographic gun.
• Marcel Duchamp, Nude descending a staircase.
• Umberto Boccioni, Unique Forms of Continuity in Space - see at the Tate Modern.
• James Turrell and skyspaces.
• Richard Long, A Line Made by Walking.

3. Text compression.

• Text compression is looking for patterns in text so that you can store those patterns, rather than the original content in order to reduce the file size of the text.
• Data compression is the general task of compressing any kind of information to save on bandwidth for transmission or file size for data storage, both of which used to be a lot more limited than today, to see how expensive and limited storage used to be, see this article.
• See this Computerphile video on Elegant LZ77 compression for more information.

4. Spatial compression and Temporal compression.

• JPEG is spatial compression for still images.
• MPEG is temporal compression for moving images and sound.
• Glitch and Glitch Art.
• See Rosa Menkman's amazing series of lectures on artefacts that result from accidents in both analogue and digital media (such as glitch, encoding and feedback).

5. The Fast Fourier transform.

• The Fast Fourier transform is a way of splitting up any waveform into a series of simpler waves.
• This can be very useful to find out how much bass, mid and treble any sound has and is used in music visualisers.
• See this great interactive website for an explanation and further links.
• See this interactive Better Explained article for a further, further explanation.

6. Bonus: three kinds of feedback: audio, visual and interactive.

• Feedback is when you feed the output of a signal into the input of it. It's a very powerful technique that can be used in a variety of fields:
• Audio feedback. Jimi Hendrix used this to great effect.
• Video feedback, the video equivalent.
• Nam June Paik, TV-Buddha. Media Art Net is a great resource.
• Douglas Trumbull, 2001 Star Gate Sequence.
• An Informal Catalogue of Slit-Scan Video Artworks and Research by Golan Levin. Slit Scan p5.js demonstration by Daniel Shiffman.
• Going around the corner piece by Bruce Nauman.
• Tell the story of making audio reactive visuals for Massive Attack in 2008.
• Finally, a great Twitter thread on the history of new media art from Greg J. Smith.

Thanks!

• More about me: @joelgethinlewis
• Get in contact via: www.joelgethinlewis.com
• Website:
  https://jgl.github.io/ComputationalThinkingIntensive2020
• Today's slides:
  https://jgl.github.io/ComputationalThinkingIntensive2020/lecture4.html