The process I’m going to follow will be to expose the sensitized glass, develop it in a basic developer, and then etch in HF acid. The areas of the light sensitive film receiving light should become “hardened” so they adhere to the glass after the development process and during the etching process. The end result should be that dark areas of the exposure are frosted (opaque) and the light areas of the exposure are see-through. I also hope to complete the process on a piece of copper board leaving copper in the light areas and nothing in the dark areas.

Pictures are of the (hopeful) view, and the camera itself, lashed to a railing.

I’m not quite sure how long to let it go. Normally, the film takes 15 minutes to develop under a 100W full-spectrum lamp at 10 inches. I’m guessing with a 1/16″ diameter hole, it could take months.  Fingers crossed, I don’t want to have to repeat this…

Update

I was impatient and peeked at the film as it was progressing. The blue color indicates it has been exposed while the greenish color indicates non-exposure. As you can see, the skyline was recorded–the bright sky causing the blue exposure and the buildings due to their non-reflectivity, left parts unexposed. Unfortunately, there must not have been enough light because developing the film ate away the exposed areas as well. Back to the drawing board.

Over the years I’ve played with a number of tools for audio processing: Matlab, jMusic, a Java library for algorithmic composition, Nyquist, a Lisp-based synthesis/analysis environment, Beads, another Java library for synthesis and analysis, and Supercollider, another synth/analysis environment with smalltalk-like syntax. All of these are powerful tools, but aren’t as engaging in terms of interactivity. Having been forced to use LabVIEW in the past, another dataflow language, I was initially reluctant to pick up another, but for audio work, it’s been great. It is so easy to try new ideas without any need to recompile. It’s a lot like playing with a running circuit.

So far I’ve used to to analyze sound and control some lighting panels to create a reactive environment, synthesize tones for my invisible chimes project, and do some other synth experiments. This brief subtractive synth test uses filters to shape pink noise into hazy tones forming a chord. synth2 tinkers with sample playback and ring modulation. Next up, granular synthesis to build some instrumental Christmas music?

Other Useful Audio Software

Jack is a great tool for routing inputs and outputs on your system. It has made it really simple, for example, to send the output of iTunes to Pure Data, which allows me to sample chunks, process them, and mix it back into songs playing. I made a small program that samples chunks of the last song and then injects them into the new song when it detects beats. It also supports plugins, so you could use Pure Data as a signal processor for other programs like Logic.

Wiretap Studio is really useful for capturing any sound source on your system, doing basic waveform editing, fades, effects, and exporting to any other sound file format.

RjDj for the iPhone is a program that lets you download (and create, using Pd) “scenes” that generate music or process environmental sound and play it through the headphones. For example, one might identify that fan humming along at 300 Hz and re-inject overtones to change its timbre.

The trackmate system examines an image (in this case coming from a cheap webcam) and looks for special coded labels. Each label contains a unique ID and also encodes its rotational direction. When trackmate identifies a label, it sends the id, position, and rotation to my software in processing which in turn draws lines.

The screenshot was taking during an interactive session where one person was controlling the color, the other was controlling the opacity, and the third was moving the brush.

The lines in the drawing are broken up due to the low resolution of the camera (this could have possibly been solved with interpolation). I need to calibrate the camera again (and really, buy a cam with a res higher than 640×480), and find a better surface that will filter some of the ‘noise’ from the scene. Still, trackmate behaved remarkably well given the circumstances.

The trackmate website has good tutorials on how to get a system up and running. My source code is provided to help get you started if you want to play around with the system, although I accidentally lost the final revision, so the code provided may not function as expected.

To use the code you’ll need a copy of Processing. Shine a bright flashlight against your thumbnail (I used a bright LED flashlight) and place your thumb over the webcam lens so it completely blocks it. Try to hold as still as possible.  The brightness of the red channel is measured each frame and a running average is kept. If the brightness drops below the recent average, a small circle is drawn representing a contracting heart.

If it is unreliable, you may need to tweak the navg parameter and/or find a way to stabilize the light source, finger, and camera, as small shifts will cause a change in the amount of light detected by the camera.

Download the Code