The story of photography will be, in no small part, that of itsfile formats, the kinds of compression and storage it undergoes, as they in turn produce what is conjurable as an image.
(Matthew Fuller 2012)
The first edition of this book was published in the very early years of the World Wide Web. A single reference to the internet in the index points to a definitional note in one of the essays, where it is described in terms of‘so much information that it is often difficult to find what you want, and the interface is very “user-unfriendly” with not-very-descriptive filenames, etc.’ The author adds that ‘Images can be downloaded, but this takes a long time, and the images tend to be b/w and very low resolution’ (Graham 1995: 92). Needless to say, things have changed. Today, high-quality colour photographs circulate on the internet in overwhelming abun- dance, and since 2001 publicly available images have been searchable via Google’s dedicated image search function. In 2011, Google even made it possible to search for an image using another image. That we tend to take all of this entirely for granted can be read as a measure of the success of the various technical standards that have enabled it to happen. Technical issues were judiciously downplayed in the 1995 edition of this book, in an effort ‘to think about photography as a set of practices with different purposes’ (Lister 1995: 14) and to complicate the myth of a ‘clean break’ between analogue and digital photography (Lister 1995: 20). Most writers on digital photography had, until that point, been overly preoccupied with the transformation from chemical photography as a physical object to a generic ‘digital image’ of zeros and ones. However, technology cannot be easily separated from cultural practice, and just as‘analogue photography’ was always more than one technology, ‘digital photography’ is born of a series of technological innovations and conven- tions. In this chapter I focus on one such innovation, the ubiquitous JPEG file
format, which I understand as a materially significant dimension of digital photo- graphic practices. Although it might seem an unpromising topic, I seek to unpack its ubiquity as the default mode by which we currently experience photographs on- screen, and argue that the JPEG is rhetorically linked to the idea of visual democracy in an age of networked photography.
More than 50 years ago, Roland Barthes famously called the photographic image ‘a message without a code’ (Barthes 1977a: 17). Barthes was concerned with the photograph’s illusionary transparency, its apparent naturalness that concealed what he identified as the ‘denoted’ and ‘connoted’ meanings at work in its interpretation. Three years later in‘The Rhetoric of the Image’ (1964), Barthes suggested that the photograph ‘corresponds to a decisive mutation of informational economies’ (Barthes 1977b: 45). Hinting at the medium’s indexical nature that later preoccupied him in Camera Lucida, Barthes explained that‘the relationship of signifieds [what is represented] to signifiers [the forms of the image] is not one of “transformation” but of“recording”, and the absence of a code clearly reinforces the myth of photographic “naturalness”’ (Barthes 1977b: 44). Barthes argued that since all images are polysemous (having more than one potential meaning), reading a photograph therefore involves a rhetorical analysis of the cultural codes within which it make sense to readers. Yet the photographic image itself remains, paradoxically,‘a message without a code,’ since it is grounded in analogical representation and captured mechanically (Barthes 1977b: 36). This claim was always debatable, but it is literally untrue in the case of digital photographs that are comprised of nothing but code. Barthes was referring to cultural codes that conditioned representation, but there is equally nothing natural or neutral about the digital code that lies behind the images we now see. Just as the myth of photography as a universal language has been destroyed, digital images are not universally intelligible or, as it were, equally capable. Unlike the character in thefilm The Matrix (1999) who can seamlessly translate streams of green data into images, digital code operates by being largely invisible to human viewers and readable only by machines. As one observer put it recently, digital code is‘inher- ently alien to human perception… Convert any .jpg file to .txt and you will find its ingredients: a garbled recipe of numbers and letters, meaningless to the average viewer’ (Bishop 2012: 441).
Charge-coupled devices (CCD) were already under development when Barthes published those influential essays. By the late 1960s, CCD sensors could convert photons to electrons, collecting light and converting it to a voltage charge and a numerical code. By the mid-1970s, computer programmers were at work developing compression techniques that would eventually lead to standards such as the JPEG and TIFF. Digital photography is encoded all the way through, in elaborate algorithms built of zeros and ones, yet this code remains as invisible as the cultural codes that govern the reading of images. Indeed, under ordinary circumstances, when we see a digital image on-screen, or printed on paper, its numerical basis is actively repressed. The makeup of the image only becomes visible when the algorithms are pushed to their outer limits, typically in the form of cosmetic disturbances such as jagged edges. As I will explain in detail below, these noticeable distortions– which can similarly
affect audio and video media – are known as ‘compression artifacts’ because they are caused by the application of ‘lossy data compression’. Typically an undesired outcome of an editing or distribution procedure, unforeseeable but substantive, they are an ‘accident’ built into the program itself. A product of the desire for immediacy, they can be read as part of Paul Virilio’s political economy of speed, in which technology and the accident are caught in a dynamic and fatal relationship (Virilio 2007).
Compression artifacts have themselves become objects of exploration by artists and photographers, most famously by Thomas Ruff in his jpeg series (2004–07). In these large-scale photographic works, the German artist not only reveals the pixel grid through the enlargement of digital images, but purposely degrades the images to produce a kind of impressionistic abstraction when viewed up close. Ruff became interested in the effects of JPEG compression after looking for images of 9/11 online, and one of the most famous images in the series depicts the Twin Towers of the World Trade Center in clouds of smoke. Ironically, given the images are largely sampled from the internet (combined with private holiday snapshots)– re-scaled and then recompressed in his words‘as the worst possible quality JPEGS’ (Lane 2009: 138)– Ruff’s images demand to be seen in the flesh as gigantic prints. But the very fact that his images are named after a compression format for digitalfiles means, as Bennett Simpson argues, that it is‘impossible to view Ruff’s photographs as pictures without simultaneously viewing them as processes. Their content stands for their condition’ (Simpson 2009: np). That condition, of course, is the proliferation of
digital images online, and the promiscuous mingling of press and personal images. By producing museum-scale physical versions of low-quality popular imagery, Ruff seems to make an analogy to the fragile state of mediated human memory in an age of image overload. In this sense, the image of the Twin Towers is something of an update of Andy Warhol’s Death and Disaster series of silkscreens (1962–63). More unusual is the reference to JPEGs in the art gallery in thefirst place. Digital photography has largely entered the gallery as a simulation of the fine print photography that preceded it – smooth and unpixellated, completely removed from photography’s more popular contexts of reception. Ruff’s jpeg series – inviting us to contemplate the structure of an image form that we normally only scan the surface of – reminds us that the unwanted artifact is in fact an authentic part of digital photographic culture.
The evolution of a file format
The JPEG is worth paying attention to, if only because it is the default mode by which we currently experience photographic images on-screen, from computer monitors to mobile devices. In other words, JPEGS make up almost all of what has been called ‘transient photography’: ‘the kind of photography that most people now make, use and view most of the time … digital files that are produced, reproduced, transmitted digitally and not printed, but viewed on screens’ (Bull 2010: 28). According to a 2011 press release from the official site of the Joint Photographic Experts Group that gave their name to the format, over a trillion JPEG images have been created (see www.JPEG.org). The same press release reminds us that the format has ‘contributed to the progress of e-commerce, where digital images offer new opportunities in the form of products and services’ and that ‘the existence of standard image coding formats’ has been an ‘enabler’ of our ‘digital imaging ecosystem’. Facebook and Flickr are proudly cited as examples of this ecosystem, and indeed JPEGs make up the overwhelming majority of the 100 million photographs reportedly uploaded and shared every day by Facebook’s 750 million users (2011figures). The expressions ‘upload’ or ‘email a JPEG’ have become part of the cultural vernacular.
It is surprising, then, that so little writing on digital photography has explicitly focused attention on the meaning and significance of the JPEG. Most people probably understand that the name stands for a digitalfile format associated with the distribution of images via the internet, and photographers and media theorists would appreciate that the JPEG is a technical standard that specifies how continuous-tone image data is compressed into a stream of bytes and decompressed back into an image. But the JPEG – and other compression/decompression protocols (‘codecs’) – is almost entirely neglected in the critical literature around digital photography. On the one hand this is unsurprising, since this writing has been dominated either by art historians, for whom the final image is privileged as an expression of a singular vision, or by social theorists, for whom photography is a cultural practice. For both groups, discussion of the technical means of its production is largely considered irrelevant. It
could be argued that few people in the analogue period appreciated the significance of Kodak, Agfa or Fuji film stock either (despite Kodak’s attachment to Caucasian skin tones as the normative standard). A photographer’s choice to use one or the other was based on habit and aesthetic preference rather than a technical knowl- edge of the materials. However,file formats are more consequential than film, not least because they are not something we necessarily choose to use. Instead, they are usually built into cameras and software as the default. Their aesthetic and cultural implications should matter to both art historians and social theorists.
Perhaps the real reason why so little is known about the JPEG is that it appears so ‘natural’, and so concurrent with the digital era. Paul Caplan, one of the few writers to pay attention to this point, notes that the JPEG has become so familiar that it has ‘become transparent and taken for granted’ (Caplan 2010: 1). And indeed, the history of the JPEG– buried in obscure reports and technical releases – is largely unremarkable and controversy free. It started with early research in the 1970s around the ‘discrete cosine transform,’ a complex trigonometric formula for ‘decorrelating’ image data, to enable the prediction of pixel values based on neighbouring pixels – thereby reducing (and in some cases eliminating) interpixel redundancy. International standards bodies began the push for a generic image compression standard in 1982, responding to a need to foster the implementation of new digital image coding equipment. This resulted in the formation of the aforementioned Joint Photographic Experts Group in 1986, a joint committee between the International Organization for Standardization (ISO) and the Inter- national Telecommunication Union (ITU). Founded in 1947, the ISO promulgates worldwide proprietary, industrial and commercial standards– and was also responsible for the measure of photographic film’s sensitivity to light (‘film speeds’ such as ISO100, ISO400, and so on). The official JPEG standard dates to 1992 in Geneva, although it was already in use a few years prior.
German media philosopher Friedrich Kittler has described computing as a‘general interface between systems of equations and sensory perception’ (Kittler 2010: 228). Indeed, the JPEG format was designed to exploit the human eye’s differing sensitivity to chrominance and luminance, and specifically to discard information that the eye cannot easily see. Essentially this means the so-called‘redundant data’ of subtle colour distinctions and high frequency brightness variations imperceptible to the human eye (Murray and Van Ryper 1996). However, since the quality of an image declines as data is removed, JPEG compression is also considered‘lossy’. The original format offers only 8 bits of data per colour, providing a relatively coarse 256 levels between complete darkness and complete brightness (newer versions of the standard, such as JPEG2000, remain marginal). As a consequence, images containing large areas of a single colour, such as blue skies, are prone to a form of compression artifact known as ‘posterization’ or ‘banding’, where a continuous gradient appears as a series of discrete steps or bands of colour (the human eye perceives a blue sky as millions of gradations of colour). Nevertheless, a 20:1 compression ratio can be achieved without noticeable loss of quality: thus a one megabyte TIFF (Tagged Image File Format) – Adobe’s popular format for high
colour-depth images – can be converted into a snappy 50 kilobyte JPEG, and so on. If rhetoric is classically defined as ‘the art of adapting discourse, in harmony with its subject and occasion, to the requirements of a reader or hearer’ (Genung 1900: 1), the rhetoric of the JPEG is that of reducing an image’s file size to the minimum while magically suppressing attention to that loss.
Smaller file sizes are valuable for two important reasons: to save storage space (memory or disk), and for faster transmission across networks (to enable faster downloads and copying). Since JPEG compression was developed at a time when computer memory was expensive, camera makers welcomed more imagesfitting on a memory card. Moreover, the official release of the JPEG format effectively coincided with the first popular graphical web browser, NCSA Mosaic, in 1993, quickly followed by Netscape, Internet Explorer and others. It could be argued that having evolved out of existing phone networks as a text-based medium, the popular explosion of the World Wide Web in the mid-1990s occurred only when browsers could display pictures in addition to text. In those early years of slow dial-up modem connections, so-called‘progressive JPEGs’ were commonly used to divide imagefiles into a series of scans for progressive rendering as they gradually loaded. Thefirst scan, which arrived quickly on screen, showed the image at the equivalent of a very low-quality setting. Each successive scan gradually improved the quality, with the image slowly losing its blurriness and becoming clearer. At the time, when the World Wide Web was far more textual than the audio-visual experience it is today, the option to‘disable images’ in the browser preferences was a very practical one for many users.
Lev Manovich has suggested that rather than ‘an aberration, a flaw in the otherwise pure and perfect world of the digital … lossy compression is the very foundation of computer culture’ (Manovich 2001: 55). Put another way, it is built into its very economy. Indeed, in tandem with the rising popularity of the internet in the 1990s, amateur photographers proved unexpectedly content to accept a lower-quality image for the convenience of digital photography. Even Kodak eventually admitted their early miscalculations on this front. Although a pioneer in thefield of research into digital photography in the 1970s, Kodak came belatedly to promoting and manufacturing digital cameras for obvious reasons– since the bulk of their profits were generated from manufacturing and selling film – and mistakenly believed thatfilm sales would continue to flourish simply because celluloid produced a superior image. They also believed that sales would grow in developing markets, where computers were less common. Kodak, perhaps more than any other company– given their success had always related to mass market value and ease of use– should have understood that economics and efficiency would eventually win out over conventional measures of image quality.
From image quality to image currency: the role of software
Image quality remains the dominant discourse within which JPEGs are understood. Thus, a typical consumer photo-lab will proffer advice regarding the level of JPEG
compression that‘will not lead to visible loss in quality or detail’ in the print. More dramatically, a best-selling guide to Adobe Photoshop proposes that ‘shooting in JPEG mode is like taking yourfilm to a high street photo lab, throwing away the negatives and then making scans from the prints’ (Evening 2008: 120). For ‘serious’ amateurs and professional photographers, JPEGs have come to be considered as degraded, even inauthentic, copies of a camera’s sensor data. These photographers prefer so-called RAW and DNGfiles, which are akin to ‘digital originals’, wherein the image is uncompressed and camera settings are saved separately from the image data (ironically, RAW files are proprietary formats specific to different camera manufactures, which led Adobe to develop the open standard DNG, short for ‘digital negative’). The JPEG algorithm not only disposes of potentially valuable sensor data, but is also associated with irreversible changes to the pixel arrangement (known as‘destructive editing’). The growing awareness that to post-process JPEGs is to risk an avalanche of unwanted artifacts has also focused attention onfile formats, at least among more committed photographers. Others are concerned with the issue of format obsolescence that has long plagued professional image archivists (will a JPEGfile be readable in 50 years?).
But image quality and permanence are not the whole story. Much more is at stake, since the JPEG format is part of the new computational logic of photography that gives the image an entirely new currency. Indeed, the production of‘in-camera’ JPEGs is compromised for the previously-mentioned serious photographers by ‘in-camera’ processing, in which variables such as colour balance and sharpness are set automatically at the moment of capture, as opposed to theflexibility of choosing such settings afterwards in professional software such as Photoshop, Lightroom or Aperture. In certain respects, the increasingly blurry distinction between‘in-camera’ or ‘on computer’ processing updates a familiar craft-versus-automation tension. Don Slater has shown that the history of popular photography elicits a conven- tionalization of how things can be photographed, in which, after Kodak, ‘Taking photographs is itself structured … as the paradigm of structuring a complex skill into a few simple actions’ (1996: 134, 141). Julian Stallabrass has similarly argued in relation to electronic SLR cameras that relieving the camera user of manual control has the paradoxical effect of mystifying the camera’s processes (Stallabrass 1996). In practice, today, varying levels of automation are available depending on the cost of the camera equipment and the desired outcomes. A wedding photographer, for instance, may opt to shoot in JPEG mode to speed up their ‘workflow’. On the