The World in a Pixel

Pixel processing, circa 1995. Photo: Ihtisham Kabir

Pixel” is a compaction of “picture element.” It was coined in the late 1960s when engineers and scientists in the United States started transforming photographs into a digital form. While the rest of the world ran on film, engineers at Jet Propulsion Laboratory, wanting to help NASA deal with pictures taken and sent back by its spacecraft, started looking at digital pictures. Folks at Eastman Kodak were figuring out how to place all three layers of colour pictures into one digital sensor. MIT researchers worked the mathematics with two-dimensional grids of numbers representing brightness, including, for example, how to sharpen such an image. These ground-breaking activities – and trails blazed by pioneers at other universities – were the forefather of today's digital photography.

My first brush with digital images came in 1979, when I was an undergraduate engineering student in the United States, and pixels were confined to expensive laboratories. I was browsing the shelf of new books in the library one day when I ran into one on computer pictures. Opening it I came across a line of reasoning that profoundly influenced my subsequent career.

The author was proposing a thought experiment that I paraphrase below:

“Imagine a square grid with 256 rows and 256 columns. Now imagine each cell of the grid has a number between 1 and 256, 1 being black and 256 being white. Numbers in-between represent shades of grey. Then this grid actually represents a black-and-white picture.”

So far, so good – if you are not mathematically inclined, please stay with me because the climax of this thinking does not require mathematics. Our thought experiment continues:

“The total number of different pictures you could make on this grid would be very large but finite: 256 multiplied with itself 256 times, or 256 raised to the power of 256.”

Finally, the conclusion that boggled my mind:

“And among those pictures would be the face of each and every person who walked or will ever walk on earth. In fact, there will be many, many pictures representing each person.”

I thought that was a deep insight that might change the world.

And indeed it did. Initial progress was slow because computers lacked power. But as they became more powerful, the grid of numbers, called a digital image, became bigger, better, and easier for people to use.

Each number in that grid is a pixel. My entire software engineering career was devoted to making these tiny pixel thingies run fast. When I started work in Silicon Valley in 1983, I wrote “code” for a machine the size of a refrigerator and costing a few hundred thousand dollars. It did a fraction of what you can do with photos on your cellphone today. During the next decade or two the power of that large machine was miniaturized into desktop and laptop computers. I played a small part in this revolution. At Sun Microsystems I led teams of engineers to build computers that, for the first time, had pixel computing integrated into them, a technique that sees widespread adoption today. In parallel, the silicon technology needed for squeezing ever more pixels into a digital camera also evolved.

And so the pixel was unleashed from the laboratory to every corner of the world, far and wide. From selfies to drones to closed circuit TVs to scans of your unborn children, the pixel is everywhere and here to stay.

Seeing the state of today's imaging technology, I often wonder what Henry Fox Talbot, the inventor of photography, would say. Would he be shocked? Amazed? Or boundlessly delighted?

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