Resolution Again

I introduced the concept of resolution a few posts ago and focused on the idea that analog recording formats might have “infinite” resolution. They don’t. The smooth flow of electrons through wires or the movements of a stylus through the groove of a stereo recording don’t have any resolution at all! They are “analog” models of the original waveforms that were captured by the microphone. The only proper way to discuss resolution is to move to the digital domain. Digital recordings are based on a finite math. I remember taking a class as part of my graduate degree in computer science and having to limit my thinking AND calculations to a bounded world or numbers. Computers have limits on the numbers that they can represent. The binary world of bits and bytes and 32 or 64 bit words means that there’s always a discrete number of values that can be accurately represented. Is this a problem for digital PCM music?

No, it’s not.

Let’s move to the world of digital photography for a moment. Over the span of 20 years or less digital photography has almost complete disrupted the analog world of photography. I don’t think anyone at Kodak or Polaroid imagined that it would happen so quickly…but it did. There has been a steady march of increasing resolution associated with digital photography just like we’ve moved from 8-bits to 16-bits to 24-bits (and now some are introducing 32-bit converters…that’s a topic for another post!) in audio.

The specification for resolution in digital photography is referred to as the megapixel count on the CCD chips that captures the light coming through the lens. I had an early digital camera that I though was pretty good back in the late 90s. It was a Panasonic PV-SD4090 and I still have it (I just pulled it out of the cabinet above my office desk!). It boasts of having 1.3 Mega Pixels of resolution, a USB port and 120 MB Super Disk for storing the images. I got it because it could do time lapse photography. I would set it up in the back of a venue and let it take a picture every 5 minutes or so as we setup our sessions.

A quick look online and it’s obvious that the days of 1.3 mega pixel cameras is long gone. The new iPhone 5 has 8 mega pixels and professional Canon or Nikon cameras have over 30 mega pixels! As with audio samples, each pixel (or picture element) holds a single piece of the image. The pixel is a single square of color chosen from a finite number of colors restricted by the “palette” available. The larger the number of bits associated with each pixel the more choices that are available in the palette. Sound familiar? In digital audio, we have more amplitude choices with 24-bits than we had with 8-bits. We get more values for a wider range of dynamic levels and thus more potential dynamic range.

To be continued…