Transforming existing Sonograms into sound

Hi

I'm a newbie getting into FFT and sound processing. I'm trying to do something very simple--take an existing sonogram image and transform it into sound that can be played back at various rates. All the tutorials I've seen generally generate a amplitude/phase matrix from recorded sound. I'm trying to load a preexisting image (jpeg) of a sonogram into a matrix to be read by some object that will produce sound when it 'reads through' the sonogram.

Any ideas on how to do this?

Thanks so much -- any advice would be greatly appreciated

best,
melonhead