Hendy's Law

In 1998, Barry Hendy of Kodak Australia pointed out that the number of pixels on a digital camera that you could buy per dollar was growing exponentially. At the time, that would have been about 1000 pixels per dollar. Today, in 2014, you can get roughly 1 million pixels for a dollar (The Vivitar VX137 with a 12.1 megapixel sensor is selling on Amazon Prime for $12.99.) This line has continued exponentially, doubling every 18 months or so, since at least 1994. A camera pixel is a chip component, so you would expect this to track Moore's law more or less. If the trend continues until 2030, you could get a gigapixel for a dollar. At that resolution, you could routinely see the photographer by zooming in on the reflection in the eye of the subject being photographed.

The optics of the Vivitar probably don't support 12.1 megapixels, really-- at 100% zoom level on Photoshop, I expect the image would look very blurry.

Here is a graph Hendy created around 2005. Note that the price is showing only the best deals on pixels per dollar in a new camera at any point in time-- DSLRs have always been more expensive, of course.)