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The concept of digital photo frames would, of course, never have existed without the advent of digital cameras, and digital photography. Remarkably, even though the first digital cameras for the consumer market appeared in the 1990s, digital photo frames, recognisable as such, have only been in existence for a year, or two, and the technology is still in its infancy.
Nevertheless, digital photo frames have proven, and are continuing to prove, extremely popular with consumers – according to the RSI (“Retail Sales Index”) from the Office for National Statistics in the United Kingdom, digital photo frames sales at Christmas 2007 increased by no less than 1200% – and the reasons are plain to see. Digital photographs can, of course, be downloaded to a PC, or laptop, for editing, manipulation and distribution via CD, DVD, electronic mail, or the World Wide Web, but digital photo frames provide a simpler option for those without an Internet connection, or even without a computer.
Digital photo frames look, for all the world, like traditional photo frames, but are able to accept memory expansion cards, so that digital photographs can be transferred directly to the frame, simply by transferring the memory card, in its entirety, from a digital camera. Digital photographs can typically be displayed singly, or as an ever-changing slideshow, on an LCD (“Liquid Crystal Display”) and some digital photo frames even allow you to control them remotely, via the Internet.
History of Digital Photo Frames
Digital photo frames are a recent innovation, so their history is, by definition, brief. However, digital photo frames are, to all intents and purposes, rudimentary computers; designed specifically for the sole purpose of displaying digital photographs in their best light, but, nevertheless, requiring the same components as a PC, or laptop – CPU (“Central Processing Unit”), memory, etc. – albeit in much simpler form.
Most digital photo frames have some ROM (“Read Only Memory”), in which a basic operating system – a software component that manages hardware and software resources, including, for example, sending output to the display screen – resides. Instead of volatile RAM (“Random Access Memory”) – volatile in the sense that any data it contains is lost when power is removed – digital photo frames, however, use solid state, “flash” memory instead.
Flash memory is a form of EEPROM (“Electrically Erasable Programmable Read Only Memory”), which can be erased and reprogrammed – that is, “flashed” – in large blocks, and is non-volatile. This is the type of memory – in the form of removable memory expansions cards – popularly used in digital cameras.
The LCD panels used to display photographs, too, are of the same type as that used in flat panel television sets and computer monitors. It is therefore easy to trace the evolution of digital photo frames by examining the technological advances in each of their component parts; these, together, allowed the sophistication of digital photo frames to increase along with their popularity.
Digital photo frames typically have little, or no, integral memory – 256MB is usually the absolute maximum available – and therefore rely on memory expansion card technology to determine the number, quality and size of digital photographs that can be stored.
Perhaps the most popular memory expansion card ever – and certainly the most successful of the “early” memory card formats – is CompactFlash® (CF), originally introduced by the SanDisk Corporation in 1994. CompactFlash® cards originally existed in two different types – “Type 1” and “Type II” – both which measured 42.8mm x 36.4mm in surface area, but differed in thickness, and were therefore not interchangeable. CompactFlash® cards, nowadays, are available in storage capacities up to 4GB – the SanDisk Extreme III CompactFlash® Card, for example – but, for FAT (“File Allocation Table”) based digital cameras, the FAT32, as opposed to the FAT16, file system must be supported to enable storage capacities above 2GB.
The Secure Digital (SD) – the result of a joint effort by Matushita (Panasonic), SanDisk and Toshiba (a.k.a. the “SD Association”) – was introduced in 1999. Secure Digital offers storage capacities from 16MB to 1GB, in a card that measures 32mm x 24mm x 2.1mm and weighs just 2g. The “Secure” in “Secure Digital” refers to CPRM (“Content Protection for Recordable Media”), a technology originally designed to prevent illegal copying of music, and other commercial media. The Secure Digital specification was subsequently extended, ultimately resulting in the SDHC (“Secure Digital High Capacity”) card, with storage capacities between 4GB and 32GB and guaranteed minimum write speeds (2MB per second for “Class 2”, 4MB per second for “Class 4” and 6MB per second for “Class 6”).
Other manufacturers, notably Sony, Olympus and Fujifilm, also introduced their own, competing, flash memory products from 1999 onwards. The original Sony Memory Stick® was introduced in that year, and it, too, has evolved significantly in the interim, such that the latest Memory Stick PRO Duo cards offer fast data transfer rates and storage capacities up to 8GB. The Standard xD Picture Card™ – a tiny, 20mm x 25mm x 1.7mm, card, nevertheless offering storage capacities up to 8GB – was introduced in 2002, and, itself, superseded by the “Type H”, High Speed xD Picture Card™ (offering data transfer speeds up to 200%, or 300%, faster than the original) in 2007.
These advances in memory expansion card technology effectively mean that digital cameras, and digital photo frames, can be smaller, without sacrificing storage capacity. Many digital photo frames, nowadays, have multiple slots for the popular types of memory expansion card – increasing their versatility if, say, you change your digital camera, or want to display digital photographs taken by someone else – and screen sizes range from 1½” (suitable for hanging on a key ring) to 15″ (suitable for hanging on a wall), with 7″, or 8″, considered a happy medium for a desktop, coffee table, or mantelpiece.
The ease with which digital photo frames can be viewed, especially from a distance, or from different points around a room, depends on the size, resolution – that is, the number of individual picture elements, or “pixels”, of which the display is composed – brightness and viewing angle of the LCD panel employed in the frame. Modern digital photo frames typically score highly for all of these characteristics, thanks to a technology known as “active matrix”, or TFT (“Thin Film Transistor”). The first TFT LCD display was invented as long ago as 1979, and the technology was first used, commercially, in the early flat panel television screens of the 1980s. Thin film transistors are minuscule transistors and capacitors, which are arranged in a matrix on the glass substrate of an LCD panel, and allow the voltage supplied to liquid crystal molecules – and hence the degree to which the molecules untwist, permitting the passage of light – to be controlled very precisely. From the late 1990s onwards, the resolution of LCD panels increased from VGA (“Video Graphics Array”) resolution (640 x 480 pixels, with 16, or 256, colours) to XGA (“Extended Graphics Array” resolution (1,024 x 768 pixels) to UXGA (“Ultra Extended Graphics Array”) resolution (1,920 x 1,200 pixels) and beyond. These technological advances mean that a typical 7″ digital photo frame, today, is capable of displaying bright, clear images – a resolution of 480 x 234 is about standard for digital photo frames of this size – through viewing angles of 170°, even in conditions of poor ambient light.
Other technologies, of course, have also not stood still, and while some early digital photo frames may only have been capable of displaying JPEG images, other picture formats – such as GIF, and TIFF – are increasingly supported, along with MP3 audio and MPEG4, or DivX, video, captured by a digital camera in “movie” mode, and downloaded from the Internet. USB (“Universal Serial Bus”), Bluetooth®, and “WiFi” (“Wireless Fidelity”) wireless networking technologies are also becoming more commonplace, allowing digital photographs to be uploaded to a digital photo frame, wirelessly, from a Bluetooth® enabled camera phone, for example. Many of the latest digital photo frames also support Internet connectivity, and remote control, such that it is possible to send not only digital photographs, but also streaming content, such as RSS (“Rich Site Summary”) feeds, or online galleries, to the frame from any location that has Internet access.
Finally, to bring the story of digital photo frames completely up to date, the largest digital photo frame in the world, the Smartparts SP3200, was introduced at the CES 2008 show in Las Vegas, and features a 32″, widescreen aspect ratio (16:9), LCD panel with a maximum resolution of 1,366 x 768 pixels, and a price tag of around £400.