The earliest computer images were relatively simple and by modern standards low-tech affairs. The first systems were filmstrips with content assumed to be reasonably close to whatever topic the computer's user wanted to display, and despite a few occasions where instead of summary of a computational fluid dynamics prediction of air-flow around a new automobile design the projector showed a Snoopy calendar, we were reasonably happy, particularly if we got to work the projector and doubly so if we were allowed to make the ``beep'' noise along with it. They were simpler times, and much of the audience had grown up in the ``golden age'' of radio and was happy to imagine the pictures.
But as the need for sophisticated images grew the filmstrip came to be ignored, until about four years ago when the computer industry sat up in the middle of the night and wondered how long it had been since they did last see a filmstrip. It had been eighteen years. But it is in that more than eighteen years -- indeed, some day it will be more than nineteen years -- that digital images have grown popular in the computer world.
The first digital images were simply pictures of the pointer finger of several lead programmers aimed in different directions. This finger was chosen for ease of indexing. This format was very good for pictures of fingers, or on large enough screens for strange brownish grass, but it was a transitional phase to making digital pictures out of numbers instead.
The first numbers put to use in digital images were 1 and 0. The 1 was the more popular initially, since it so resembled a finger that most of the old techniques for doing images still worked. And if you had a typeface that included a few modest serifs then your problems in drawing an upward-pointing arrow were finally solved.
The 0 was harder to use, until finally it was discovered this simple numeral could represent distant planets, nearby marbles, and olives stuck on intermediately-distant fingers. This young and in retrospect naive time was brought to an end by the discovery of the number 5, which resulted in a hasty year-long industry-wide effort to prove the existence of 2, 3, and 4. The 3 remains unknown, but is believed to live in the wilds of Tasmania. Modern computers avoid the confusion not having a 3 would entail by using ``quarter-dozen'', or ``quatre-vingt'' as they say in inaccurate French.
With modern computers using upwards of two million colors for a single image -- admittedly, some of the numbers are reused -- it becomes all the more remarkable that they all stay organized. One of the leading formats for computer images is JPEG, which stands for `Jupiter Petroleum Export and Gravity', a corporation from the 23rd century with inexplicable connections to the modern computer industry.
The trouble with JPEG is that it is a ``lossy'' format, in which some of the numbers are regularly scattered, sometimes getting lodged elsewhere in the computer (one of the reasons computers become more sluggish as they age, as numbers build up in their wires like cholesterol in blood vessels) and sometimes rolling on the floor where you may easily trip. Worse, these losses occur every time you do something with the image, so if you have a JPEG of something precious, it is important to look at the image only when it is strictly necessary. It would be awful to have a beloved picture turned into a brownish gray simply because you've lost its numbers by looking at it too much.
The alternative is ``lossless'' image formats, which keep all the numbers together by putting bubble wrap below and above them and binding them down with sticky tape. This has its drawbacks as well, since programs which have to manipulate these lossless formats often spend the whole afternoon popping each bubble instead of doing whatever their work was. The image remains intact, but feels less special. This is why data recovery experts recommend the periodic backing up of all image data into paintings on cave walls, which will allow them, when finished, to make the ``Beep'' noise.
Trivia: The initial ENIAC development contract, as Project PX, between the Army and the University of Pennsylvania, was number W-670-ORD-4926 and came with an initial appropriation of $61,700. Source: Eniac, Scott McCartney.
Currently Reading: A History of the United States Weather Bureau, Donald R Whitnah. (And hey, it's the anniversary of the patenting of the typewriter ribbon. Remember typewriters?)