Analogue : Digital

If we wander into any art gallery which shows a variety of work we are likely to see pictures identified as “digital images”, but the term is problematic. An “image” is something we see, but in what ways can an image be “digital”? And what, really, is the artwork?

Analogue vs digital

Technically, digital is contrasted with analogue. Analogue changes in any quantity are continuous, i.e. smooth at every scale, while digital changes are discrete, stepwise. For instance, the minute hand of an analogue clock moves smoothly and its position can be read to any desired accuracy, while a digital clock will say the time is (e.g.) 8.22 p.m until it says 8.23 p.m.

Digitising any information, whether it’s an image or a daily temperature record, makes it easier to store, transmit and transform. It also sacrifices, irrevocably, some of the detail, since each bit of information is all-or-nothing: black or white, yes or no, one or zero – but no greys, no maybes, no halves or quarters.

How much detail is lost depends on the resolution of the device (clock, CD player, camera or printer), i.e., how many points are calculated in a given time or space. Resolution in space is measured in dots per inch (dpi), and varies from about 72 (e.g. the old dot-matrix printers) to 96 (many computer screens), 300 (a common printer standard), 600, 1200 or more. The higher the resolution (the more points we measure), the more closely we can approximate an analogue original.

Similarly, we can digitise colours to any desired accuracy from two colours (black and white), through the 256 colour internet palette (only twenty years ago) to the millions of colours we now take for granted.

The whole subject can become very technical (Wikipedia’s article on dots per inch is a useful introduction to it) but the key points are that (1) however high our resolution, digitising discards detail but (2) at a high enough resolution, we can’t visually distinguish a digitally processed image from an analogue one.

A matter of scale

When the image file is interpreted by the software and displayed for us on screen or on paper, the image it encodes breaks down into pixels when we zoom in close enough and then the pixels, in turn, break down into analogue artefacts when we zoom in even closer. (Whether we can still see “an image” at that stage is doubtful.)

In terms of our perception, an image is analogue (continuous) if we can’t see the dots or pixels. If we can, it’s digital (discrete). Images on screen and those printed by most kinds of printer (ink-jet or laser) will appear analogue at most scales. They can appear digital if we look particularly closely, but we very rarely do that.

In terms of ultimate physical reality, every physical object is analogue. In particular, the physical embodiment of any image is as analogue as ink and paper: zoom in close enough and the neat grid of pixels dissolves into drips and spatters on paper. The screen is also analogue, consisting of groups of pure-coloured cells in a supporting matrix.

digital print enlarged
A digital (bubble-jet) print enlarged to show both digital and analogue characteristics

Finally, any “image” which isn’t physically embodied isn’t an image because an image is something we can see. In particular, if it’s a file on your computer (phone, etc) it’s digital, but we never see the computer file and it wouldn’t look like an image if we did.

binary code
Ceci n’est pas une image

The inescapable conclusion is that all images are analogue, not digital, for all practical purposes, so calling anything a “digital image” is misleading at best. We should really be calling it a “digitally processed image” or words to that effect.

That is true of any image which began as a photograph or scanned graphic. (A scanner, by the way, is just a highly specialised camera.) There are also digitally created images which began as computer files; but the images themselves are still analogue.

mandelbrot set
Digital until seen: part of the Mandelbrot Set

The term “digital image” looks more and more like a category error.  Digital apples don’t exist; why should digital images be any more real? The logical fault inherent in the term is, however, unlikely to stop us from continuing to use it, because it is just too well entrenched.

All is not analogue

Although a digitally processed image is analogue, its underlying image file is still intrinsically and absolutely digital.

When we want to alter the image we normally work with the image file rather than the display device or printed copy. This is where we reap the advantages of digitality, as a few keystrokes can transform it radically. And then, of course, we return it to the analogue world when the altered file is interpreted by the software and displayed for us on screen or on paper.

We can also alter the image on screen without altering the file by altering our display settings (zooming in or out, or turning screen brightness up or down, for instance) but whether this alters “the image” is a matter of how we define “the image”, which is a question in itself.

Just what is the artwork?

Sculptors and painters have no trouble identifying their works of art: they simply point to the unique physical object they have created. But what is “the image”, “the artwork”, in a medium to which reproduction is intrinsic and central?

It’s a question which has exercised the minds of musicians, especially classical musicians, for years. Let’s look at the parallels.

Digital : Analogue in music

(1) Music is a transient phenomenon which exists only in performance. A piece of music is performed, but the performance isn’t the piece; if it is performed again, somewhat differently, it is still thought of as the same piece; if it is performed very differently (by orchestra instead of piano, for instance), it is thought of as an arrangement, a modification, of the same piece; if it is recorded, the recording is not the piece.

(2) Music is an analogue phenomenon. If we look very closely at the physical nature of the sounds we hear, we find a very complex pattern of changing air pressures, and the changes are continuous, not discrete. For a century, most recordings were also analogue, either as grooved plastic discs or magnetised tape, and were interpreted by analogue devices. These days the recording is usually a digital file, still digital on the storage device (CD, computer, etc) and only returning to the analogue realm in the playback device.

As with images, if the resolution of the digital file is high enough then the musical experience is convincingly analogue although the file and its processing are digital.

Digital audio files have all the advantages of digital image files: easy duplication, easy alteration, easy transmission. And, again like images, music may be created entirely digitally with appropriate software. The parallels with image storage and processing are very close indeed.


What is “the piece” in music?

  • Not the written or printed score. That’s basically a set of instructions to the musicians, analogous (perhaps) to the printing plate (stone, woodblock, etc) in the art studio.
  • Not any particular performance of it, which might be analogous to a particular copy of a print.
  • Not any particular recording of it, which is a reproduction in a different medium.

What is “the image” in traditional print making?

  • Not the printing plate. That’s analogous, perhaps, to the printed score in music.
  • Not any particular copy of a print, which is analogous to a particular performance of the score.
  • Not any reproduction in different media (e.g. a photo of an engraving), which is analogous to a recording of a piece of music.

What is “the image” in digitally processed art?

  • Not the digital file. We have already seen that it isn’t an image, and we can now suggest that it’s basically a set of instructions to the screen or the printer, analogous to the etched plate or printed musical score.
  • Not any particular copy of a print, which is analogous to a particular performance of the score.
  • Not any reproduction of it in another medium – on screen instead of on paper, for instance.
photo of a picture on a desk
ceci n’est pas une œuvre d’art

Perhaps the “the image” or “the artwork” in print-making (traditional or digital) is, like “the piece” in music, some kind of Platonic Ideal or Form, never entirely realised (i.e., literally, made real) in the physical world.

…unique physical object?

Starving in a garret has a certain romantic cachet but it’s not a lifestyle to aspire to and is not actually good for either the artist or the public. But if the image is not a physical object at all, let alone a unique physical object such as a sculptor produces, how can the artist sell it? This is where editioning comes from: the need (for commercial reasons) to make each iteration of a print unique, to give all of them a rarity value. But that is a topic for another day.

Further reading

ceci n’est pas…

Platonic Ideals

Mandelbrot Set The Mandelbrot Set is a fantastically beautiful mathematical object which is relatively simple to compute. My image is a tiny part of part of it, as rendered by a home-grown Java programme fifteen years ago. Wikipedia presents many more images (which we can all enjoy) as well as the maths (which most of us will skip).