[PD] Converting colours to sound
Claude Heiland-Allen
claude at mathr.co.uk
Tue Apr 7 17:58:21 CEST 2015
Hi Antonio,
On 05/04/15 15:51, Antonio Roberts wrote:
> I've been studying the work of Neil Harbisson for awhile and I'm
> looking to try and replicate in part the functionality of his eyeborg
> using Pure Data. I have already built a simple patch to convert pixels
> to sound but now I want to expand on it. Here's my initial research:
> http://www.hellocatfood.com/sonification-studiespixel-waves/
"I predict the development of an image to audio sequencer in the near
future."
I made a painting program in gridflow years ago, had some very basic
sonification - gridflow also had a "how to play a car" example
converting a photo by scanlines into audio with FFT.
https://archive.org/details/ClaudiusMaximus_-_Emulsion
https://archive.org/details/ClaudiusMaximus_-_DohPaintII_Session_3
https://archive.org/details/ClaudiusMaximus_-_DohPaintII_Session_2
> Colours don't directly relate to sound and so Harbisson and others
> must use a scale to assign colours to sounds. Some initial research
> brought these up:
>
> http://blogs.plos.org/neuroanthropology/files/2014/03/Harbisson-The-Sound-of-Colors-TED.jpg
> http://www.bbc.co.uk/news/magazine-16681630
> http://www.lunarplanner.com/Harmonics/planetary-harmonics.html
> http://www.flutopedia.com/sound_color.htm
The last one, in the section "Converting RGB Colors to Color
Frequencies", makes a good point - monochromatic wavelength to RGB works
fine, but RGB to wavelength is in general impossible, as colours are
spectral power distributions over continuous wavelengths. Once it's
flattened to RGB, too much information is lost to be able to recreate
the original spectrum (aka metamerism, where 2 different spectrum give
same colour sensation).
Recently I copy/pasted some colour-related stuff from Wikipedia into a
booklet (second link is layed out for printing, first one is better for
screen reading, both have the same content):
http://mathr.co.uk/misc/2015-04-04_colour.pdf
http://mathr.co.uk/misc/2015-04-04_colour_booklet.pdf
The approaches you linked seem to convert wavelengths to colour in a
straightforward way, but for converting from colour to sound I think a
different approach would be better (and indeed needed) - something more
akin to the Munsell perceptual colour system:
https://en.wikipedia.org/wiki/Munsell_color_system
a grossly simplified version would be HSV, which I used in the attached
- a bank of vcf~ fed by noise~, mapping hue to scale note, value to
loudness and pitch, and saturation to filter Q - so that white would
give high noise, grey gives a lower pitch noise, black gives silence,
fully-saturated dark green gives a low note, bright green gives a high
pitch at the same scale note. the filters glitch when the hue jumps
from 0 red (orange side) to 1 red (purple side), could be fixed with
some cleverness probably.
>
> Can anyone think of a way to translate this into pd? In the end I
> would like to be able to display a block of colour on screen and have
> that generate a specific note.
>
> Any help is appreciated.
>
> Antonio
>
Claude
--
http://mathr.co.uk
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