Spectral is an Android application exploring the mapping between images
and sound, by allowing you to take your pictures and turn them into spectrograms. Spectrograms
are a succession of sound pulses, each of which have a frequency
corresponding to a column in your original image. In receiver mode, the
application uses the Fourier transform to reconstruct images from
Spectral is now available in the Android market. Alternatively,
download the package from here.
in mind you'll have to turn on installing from unknown sources in
Settings > Applications.
Spectral also includes image manipulation tools, like brightness and contrast adjustment and special effects. Try using these on your images, and see how the resulting spectrogram changes. To save memory, Spectral is very fastidious in cleaning up after itself so make sure you save what you want to save.
The sounds it spits out can also be a bit grating, but this is a
necessary tradeoff for good vertical resolution - adding a large number
of cosine waves together, all at different frequencies, causes the
"clicking" you can hear. Try using Find Edges to turn most of the
pixels in your image black, and hear what a difference it makes.
Last updated: 7th August 2009, by Rhodri Karim.