Paint2Sound is a free application for Windows that’s designed to convert any .jpg or .bmp image, or any picture you care to draw/paint, into a soundscape.
Each pixel row represents a frequency band. The application synthesizes sine waves for each pixel row with an instantaneous amplitude determined by the brightness of each pixel in the pixel row, and then sums together all the sine waves.
There is user control over various parameters like sample rate, sound duration, how frequencies are distributed across the pixel rows and the overall level in the mix of each sine wave.
Here’s a demo of what Paint2Sound can do: