Glossary of Acronyms, Digital & Photographic Terms

Q

QuickTime
The video motion picture standard for streaming video, created by Apple Computer, but available as a cross-platform file format.

R

RAM
Random Access Memory is the solid state memory that a computer or digital camera uses to process information prior to that data being stored in a file or on a hard disk drive or a CD-ROM. A professional digital SLR camera contains over 50 megabytes of RAM to enable it to store up to 40 images in a solid burst.
      When using large files in Adobe Photoshop RAM Preferences must be set up so enough memory is allocated to the program, otherwise an Out of Memory warning may occur and image data may be lost, caused by the computer ‘hanging’.

Raster Graphics Files
See Vector.

Raw
A flexible unprocessed file format of data straight from the camera sensor. Suitable for transferring files between applications and computers with different operating systems, such as Mac OS X, Microsoft Windows and Unix. A Raw TIFF file is a file saved in TIFF mode with lossless encoding, capable of being read by multiple operating environments.
      Camera makers offer their own RAW file image processors, or programs such as Apple’s Aperture and Adobe Photoshop CS3 provide third party file interpreters.

Raw Data
Unprocessed digital Information straight from the camera sensor, sometimes regarded as equivalent to a digital negative file.

RedEye
The effect seen in photographs where ambient light is low and the pupil of the eye is opened in the subject so that the camera ‘sees’ the red blood vessels within the eye. Various techniques built in to modern cameras remove Red-Eye automatically.

Rendering a file
The last step in processing an image or series of images. In some software programs for video, such as Adobe Premiere, a sequence of video can be edited in low resolution, but when it is rendered all the effects are appear to run smoothly and in high resolution. A file is also rendered when creating a DVD from a series of video or still sound-slide shows from other programs, such as Apple iPhoto.

Removable Media
Memory cards used to capture images within cameras, or used to store data in PDA (Personal Digital Assistant) or mobile/cell phone devices. As the name suggests these cards can be removed and used to transfer data such as photographs into other electronic devices, such as laptop computers.

Resolution
The detail captured by a digital camera or scanner when recording an image, and output by a printer or monitor when printing it out or displaying it. A high-quality digital camera, like the Nikon D2Xs professional Digital SLR, will capture an image with a resolution of 4288 x 2848 pixels, or around 12MP. If this image is reproduced by a printer at a print resolution of 300 pixels per inch, the image will produce a print of 14.3 inches (36cm) by 9.5 inches (23.9 cm).

RGB (Red Green Blue)
The three primary colours used in computer display monitors. This is also the primary means of image capture from scanners and digital cameras. To ensure accurate matching of the input file with output devices such as inkjet printers, it is common to set them up using ICC colour profiles. There are a variety of defined RGB colour spaces, sometimes referred to as RGB, Adobe RGB and SRGB respectively.

RIP (Raster Image Processor)
A RIP is a computer and software program that converts vector files to a format suitable for printing. It takes a large print job and makes a series of conversions in a batch file so the printing device can interpret which dot to put down where on the page in what colour, how many times and in some cases with what sized dot.

S

Saturation
The relative intensity of a hue or specific wavelength of light, as defined by the CIE (Commission International d'Eclairage). Highly saturated images are bright intense colours, such as a bright green leaf, whereas a soft subtle pink shade would be a low saturation colour, with low values of the red and white hue.

Scratch Disk
This is a pre-defined file area reserved by image editing programs, such as Photoshop, which are used to hold and process image data while adjustments are made. If you work on a 10Mb file, your scratch disk should be three to five times that size, ie at least 50Mb.

SCSI (Small Computer Systems Interface)
It sends data between devices along the SCSI chain, allowing high-speed data transfer. A SCSI cord should be as short as possible, and the end of the chain must be terminated correctly with a terminator block. Some hard disks are SCSI drives, which read and write data faster than normal IDE drives. It is essential that SCSI devices are all powered up before the computer is switched on. Steps to provide unique SCSI addresses for each SCSI device in the chain must also be carried out.
      SCSI has been replaced by IEEE1394 (FireWire) or USB 2.0 interfaces.

SD (Secure Digital)
SDHC (Secure Digital High Capacity)
SD memory cards are used widely for compact and some DSLR cameras. The more recent SDHC card permits theoretical storage up to 32GB capacity. Care is needed to ensure card and camera are compatible.

Sensor
The electronic device employed in a camera, scanner or copier, containing several tens of thousands of photosites that, when combined together, enable pixels of information to be gathered and recorded. A CCD or CMOS sensor will describe the photo-sensitive device that captures a picture in a still or moving image electronic camera, which may be either analog or digital.

Serial Port
The outlet/inlet to a computer, to allow the transfer of data at moderate speed. A typical serial connection between a digital camera and a serial port will be 115,000 bits per second, requiring a long time for downloads. This system is being slowly replaced by the newer USB (Universal Serial Bus) and now USB 2 technology, which is capable of high-speed serial transfer of several megabits a second.

Shockwave
A file format developed by Macromedia (now Adobe) for the provision of advanced imaging files across the Internet. To see a Shockwave website it is first necessary to download the Shockwave player from Adobe. The program permits advanced motion and fade-dissolve techniques with very little download time.

Shutter Lag
Digital cameras exhibit varying degrees of delay prior to the exposure being actually captured after the exposure button is pressed. This delay is called shutter lag, or occasionally just 'lag'. A modern DSLR has approximately the same delay as an equivalent film SLR (around 58milliseconds), whereas an advanced Compact digital camera may experience a delay of 75ms or more. Early consumer digital cameras could exhibit delays of up to 600ms, preventing photography of fast-moving children.

SmartMedia
A small memory card developed by Toshiba and adopted by many camera makers early in the life of digital compact cameras for storage of image data. SmartMedia cards are thinner and less dense in image storage capability than CompactFlash or Secure Digital memory cards, and are now out of common use.

Subtractive Colour
The selective absorption of red, green and blue (RGB) light in transmitted or reflected white light. Each colour is subtracted by a dye of its complementary colour. In the case of photography these colours are cyan, magenta and yellow, (CMY). The non-colour, black, is represented by the term K, hence CMYK.

SVGA
Super Video Graphics Array. It defines a resolution of 800x600 pixels displayed on a monitor or other display device. XGA is an Extended Video Graphics Array of 1024 x 768 pixels and SXGA is 1280 x 1024 pixels. Wider format projectors can now be found with SXGA+ formats of 1365 x 1024 pixel resolution.

T

Telephoto
A lens that provides significant scene enlargement, or brings it closer to the viewer. A telephoto zoom lens, such as the Tamron 55-200mm telephoto Di II-series lens brings a subject 4x closer than the field that the eye would normally experience.

Terabyte
A terabyte is 1000 gigabytes of data. External hard drive memory units are now available for picture files and digital video at under AUD$500.

Thumbnail
A small low-res version of an electronic image. Both Microsoft and Apple Computer enable file searches through thumbnail images. Microsoft also offers extended use of thumbnails with Windows Vista and XP. Apple i-Photo provides particularly easy selection of images using thumbnails that can be scaled on the fly; in other words enlarged or reduced the instant you adjust your preferred size.

TFT (Thin Film Transistor)
A type of LCD display, commonly found as the rear screen monitor on a camera and notebook computer screens.

TIFF (Tagged Image File Format)
A file that also contains various data that describes various attributes of the image file.

Transparency
When combining two or more image files to produce a collage, it is desirable that the added image be placed on a transparent layer. This will enable feathered anti-aliasing of the added image to produce a more natural look.

TWAIN (Technology Without An Interesting Name)
The most interesting acronym in photography was first developed in 1992 at an HP technology meeting trying to come up with a name for a scanner interface. Really! TWAIN is a cross-platform standard interface to enable different software applications to acquire images from a variety of devices, such as scanners and digital cameras. The TWAIN driver comes with the device. You will sometimes see a device described as TWAIN-compliant, meaning it will work with software that is looking for a TWAIN device.

U

USB (Universal Serial Bus)
A higher-speed connector between digital cameras, scanners and printers, initially employed in Apple computers. This connection, while easier to install and access is slower in its 1.0 form than SCSI connections. Transfer rates up to 12Mb per second are achievable. USB 2.0 protocols with much faster transfer speeds match or exceed FireWire and SCSI transfer rates of several Megabytes a second and are now the de-facto standard of most cameras and computers.

V

VC (Vibration Compensation)
A new technique from Tamron to reduce handheld camera shake in longer telephoto lenses.

Vector Graphics
Graphic files consisting of a combination of lines and curves defined by mathematical objects. These objects are called vectors. Programs such as Adobe Illustrator are vector-based. This allows an object created in mathematical vectors to be scaled up or down, retaining quality regardless of size.
      By contrast, a raster image is a fixed size. As it gets dragged up in size the individual rasters or lines/edges start to show.

Vignetting
A term describing an image aberration where its corners are darkened, either due to the edges of a lens hood being visible in the shot or because the light-distributing ability of the lens is unequal over the film/sensor image area.

Virtual Memory
When using large images in programs like Photoshop, the amount of available random access memory (RAM) may be insufficient, forcing the computer to use the hard drive as virtual memory. Use of virtual memory can slow down screen re-draws based on disk access write/read time, depending on how fragmented your disk is. Windows users should regularly use the Programs > Accessories > Defrag feature to ensure the disk works as fast and reliably as possible.

VR (Vibration Reduction)
Nikon’s term for vibration reduction through optical image stabilization in a lens.

V-RAM (Video Random Access Memory)
The amount of memory processing power on the video card in a computer that takes over the job of refreshing the screen from the main microprocessor chip. In a laptop, 8MB of VRAM would today be regarded as good, with top-end units from Dell, IBM and Toshiba providing 64MB.. For the latest computer games, 128MB of VRAM may be required for the smoothest image transitions.

W

Web-Safe Colours
When converting a full-sized photo image to a size suitable for the Internet, conversion is often made from TIFF files to GIF (Graphic Interchange Format). A GIF file may contain as few as 128 colours instead of the 16 million in a photo. These 128 are predefined colours and represent a palette of colours found on all Internet browsers. When converting a photograph for web use, it is best to preview the image in a restricted colour-set browser and then use the image-editing program to control which web-safe colours are applied to colours from the original image.

WYSIWYG (What You See Is What You Get)
A term to describe a displayed screen representation of a file that when printed will appear the same.

White Balance
The control within a digital camera, either still or motion, which defines how the camera should interpret the colour temperature environment and correctly record colours using a neutral white point as a reference. The standard default would be Auto White Balance. More advanced cameras include settings for flash, sunlight, shade, fluorescent, incandescent and halogen lighting, as well as custom colour temperatures. Interior pictures with mixed lighting inputs are much more easily captured in colour on digital cameras than on film. Film is pre-balanced and requires optical filtering to correct for such colour temperature variations.

White Point
The highest brightness value in an image histogram, used as the setting point for that image's tonal range. In image editing programs like Adobe Photoshop, it is used to adjust the gamma to remove colour casts. In monitors it is the colour temperature of standard white light.

WXGA
Widescreen format 16:9 aspect ratio screens on laptop computers, usually with a non-standard resolution of 1366 x 768 pixels. Sometimes this is found as 1280 x 768 pixels.

X

XGA
Extended Graphics Array of 1024x768 pixels, generally applied to simpler computer monitor display resolution.

XR
Extra Refractive glass, as used in some of Tamron’s extended range super-telephoto zoom lenses, such as the 28-300mm VC XR lens, due for launch in the latter part of 2007.

Y

YouTube
A highly popular website for video material of all descriptions, also very helpful for finding instructional video materials on lens use, Photoshop techniques and general photography.

Z

Zip

1. A Zip disk is a small magnetic media file from Iomega, with a capacity of either 100MB or 250MB, depending on the version, first used to transport more files than would fit on a 3.5" floppy disk, which holds only 1.4MB. Now largely replaced by the 800MB CD-ROM or even DVD.
2. The original use of the term was to compress a file, literally zipping up a single file or several files into a single file that is compressed for faster transfer over e-mail or across networks. The most frequently used file-zipping program is WinZip for Microsoft Windows files. The Macintosh equivalent is StuffIt.

Compiled, written and updated by John Swainston.
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