Digital Photography Glossary of Terms

Digital Photography Glossary

Digital Photography Glossary: A

Ambient light – Using natural light in a scene.

Aperture – Behind the lens of your camera is a small, circular opening that can change in diameter to control the amount of light reaching the camera's sensor as a picture is taken. The aperture diameter is expressed in f-stops; the lower the number, the larger the aperture. For instance, the aperture opening when set to f/2.8 is larger than at f/8. Altering the aperture will also change the depth of field.

Application – A computer program, for example an image editor or image browser.

Artefacts - An image has to be compressed to fit when stored in a digital camera's memory. When this happens, any noise that creeps in will appear as angular blocks, which are known as 'artefacts'.

Digital Photography Glossary: B

Barrel Distortion - If you take a photo of a seascape with a wide-angle setting and the horizon seems to curve in the image, you've been hit by 'barrel distortion'. It happens when the camera's lens distorts an image to the extent that it appears spherized.

BMP - Refers to a bitmapped graphic file format that is often used on Windows PCs.

Buffer – Refers to memory in the camera that stores digital photos before they are written to the memory card. It enables you to shoot several photos in succession without waiting for each to be saved.

Burning – A process where you selectively darken parts of a photo with an image editing program.

...also

Burning - Taking the photographs that are stored on your camera and, via a computer, storing them on a compact disk for safekeeping.

Digital Photography Glossary: C

Candid shots - This is the simple technique of catching a subject unposed and off guard. It can create beautiful, natural-looking photos.

CCD – Stands for 'Charge Coupled Device'. This refers to the light sensor in a camera that records the image. It consists of millions of tiny light sensors, one for each pixel. The size of a CCD is measured in megapixels, and the more there are of these, the better in terms of quality.

CD-R – Short for 'CD-Recordable'. This is a compact disc that holds either 650 or 700 MB of digital information, including digital photos. Creating one is commonly referred to as burning a CD. A CD-R disc can only be written to once, and is an ideal storage medium for original digital photos.

CD-RW – Short for 'CD-Rewritable'. Similar in virtually all respects to a CD-R, except that a CD-RW disc can be written and erased many times. This makes them best suited to many backup tasks, but not for long term storage of original digital photos.

Clipping - (Also known as blown highlights.) When too much light falls on parts of a digitial camera's sensor, the site on the photo that corresponds to pixels in that region will hit the maximum value they're able to record. When the light is 'off-the-scale' like this, the sensor will simply output a flat maximum signal no matter what the actual light levels. The resulting pixels will be pure white and contain no image information.

Cloning - Refers to an image manipulation technique that allows you to remove unwanted aspects of a photograph by copying surrounding areas of the image.

CMYK – Stands for Cyan, Magenta, Yellow, and Black, the four colors in the inksets of many photo-quality printers. Some printers use six ink colors to achieve smoother, more photographic prints. The two additional colors are often lighter shades of cyan and magenta. Note that this is different to computers and digital cameras, which use varying combinations of RGB (Red, Green and Blue) to display images on screen.

CompactFlash™ – A common type of digital camera memory card, it is about the size of a matchbook and weighs about half an ounce. There are two types of cards, Type I and Type II that vary only in their thickness, with Type I being slightly thinner. A CompactFlash memory card can contain either flash memory or a miniature hard drive. The flash memory type is used more widely.

Compression - The process of reducing the storage needed for computer data - including digital photos - by encoding that data into a different form.

CMOS – Short for 'Complementary Metal-Oxide Semiconductor'. This a light sensor that offers higher resolutions than a CCD at a fraction of the cost, but are currently found in only a handful of digital cameras.

Contrast – The difference between the darkest and lightest areas in a photo. The greater the difference, the higher the contrast.

Digital Photography Glossary: D

Digital camera – A camera that captures the photo not on film, but in an electronic imaging sensor that takes the place of film.

Digital compact - This refers to the most commonly used camera as it's pocket-sized shape makes it easily portable. Digital cameras with changeable lenses - as used by professional photographers - are called digital SLR's.

Digital zoom - Some digicams can zoom in on the centre of an image by expanding it in the camera. The zoomed area appears bigger but contains the same number of pixels, so it will look blocky. Optical zoom is far superior.

Dodging – The process of selectively lightening parts of a photo with an image editing program.

Download – The process of moving computer data from one location to another. Though the term is normally used to describe the transfer, or downloading, of data from the Internet, it is also used to describe the transfer of photos from a camera memory card to the computer. Example: I downloaded photos to my PC.

DPI – Short for 'Dots per inch'. Refers to a measurement of the resolution of a digital photo or digital device, including digital cameras and printers. The higher the number, the greater the resolution and therefore the better the quality.

Dynamic Range - Refers to the difference between the brightest and darkest parts of an image. If a shot has very bright highlights and lots of dark shadows, it has a wide dynamic range.

Ditital Photography Glossary: E

Equivalent Focal Length - The focal length of a given lens expressed in terms of the field of view that length would give in a 35mm camera. This allows lenses for different camera designs to be expressed in terms of their real-world field of view. For example, a 28mm-equivalent focal length lens will always be a wide-angle lens, no matter what the actual focal length of the design involved.

EV - Stands for 'Exposure Value', which is the amount of shutter speed or aperture adjustment required to double or halve the amount of light entering the camera. It is also referred to as a 'stop'.

EXIF – Short for 'Exchangeable Image File' and refers to the file format used by most digital cameras. For example, when a typical camera is set to record a JPEG, it's actually recording an EXIF file that uses JPEG compression to compress the photo data within the file.

Exposure - When taking a picture, the camera's light meter determines how long the shutter should be open for and how wide the aperture should be to obtain the correct exposure. If an image is too dark, it is said to be underexposed; if it is too light, it is overexposed.

External flash – A supplementary flash unit that connects to the camera with a cable, or is triggered by the light from the camera's internal flash. Many fun and creative effects can be created with external flash.

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Digital Photography Glossary: F

Fill-in flash – This is additional light from an external flash, lamp or reflector that is used to soften or fill in shadow areas caused by the brighter main flash. The result is that the image is more subtly illuminated.

Fire – Slang for shooting a picture. Example: I pressed the shutter button to fire.

FireWire – A type of cabling technology for transferring data to and from digital devices at high speed. Some professional digital cameras and memory card readers connect to the computer over FireWire. FireWire card readers are typically faster than those that connect via USB. Also known as IEEE 1394, FireWire was invented by Apple Computer but is now commonly used with Windows-based PCs as well.

f-number - Also known as f-stop, the f-number refers to the ratio of the aperture of a camera's lens to its focal length. A higher quality length will have a smaller f-number, which conversely means a wider maximum aperture, and thus more light entering the lens.

Focal length - A term that describes the magnifying power of a lens: the longer the focal length, the greater the magnification; the smaller the focal length, the more wide-angle the lens.

Framing - Using an object, such as an archway, as a natural frame within the image, to help draw the eye in.

Digital Photography Glossary: G

Grayscale – A photo made up of varying tones of black and white. Grayscale is synonymous with black and white.

Digital Photography Glossary: H

Highlights – The brightest parts of a photo.

Histogram – A graphic representation of the range of tones from dark to light in a photo. Some digital cameras include a histogram feature that enables a precise check on the exposure of the photo.

Digital Photography Glossary: I

Image editor – A computer program that enables you to adjust a photo to improve its appearance. With image editing software, you can darken or lighten a photo, rotate it, adjust its contrast, crop out extraneous detail, remove red-eye and more.

Image format - This is the manner in which digital images are stored. There are various ways to store an image, including jpeg, gif, tiff, bitmap and RAW files. It's easy to identify which format is used by looking at the end of the file name after the period. For example, photo.jpeg is a jpeg image.

Image resolution - The number of pixels in a digital photo is commonly referred to as its image resolution.

Inkjet Printer – This is the most popular type of printer. It places ink on the paper by spraying droplets through tiny nozzles and can produce photo printouts that are indistinguishable from traditional prints.

Interpolation - Also known as 'resampling,' it refers to how some cameras and editing software can increase the size of an image by adding pixels in between the original ones. There are several resampling methods, including bilinear, bicubic and nearest neighbour.

ISO speed – A rating of a film's sensitivity to light. Though digital cameras don't use film, they have adopted the same rating system for describing the sensitivity of the camera's imaging sensor. Digital cameras often include a control for adjusting the ISO speed; some will adjust it automatically depending on the lighting conditions, adjusting it upwards as the available light dims. Generally, as ISO speed climbs, image quality drops.

Digital Photography Glossary: J

JPEG – The most commonly used system for compressing image data developed by the Joint Photographic Experts Group, hence the name JPEG. Strictly speaking, JPEG is not a file format, it's a compression method that is used within a file format, such as the EXIF-JPEG format common to digital cameras. Using a sliding scale between the file size and picture quality, it enables digital cameras and computers to store a large picture into a small amount of memory. Usually, if a high-quality, low-compression JPEG setting is chosen on a digital camera, the loss of quality is not detectable to the eye.

Digital Photography Glossary: K - L

Li-Ion - Stands for 'Lithium-Ion'. At the time of writing this, it is the latest kind of rechargeable battery, superior to Ni-MH. It can hold more charge, and does not suffer from 'memory effect,' where a partially chargen battery, when recharged, will only register the additional charge rather than its full capacity. Li-Ion cells are quite expensive compated to standard power cells.

Digital Photography Glossary: M

Manual mode - Provides full control over both aperture and shutter speed, which enables you to change exposure and depth of field.

Media – Refers to material that information is written to and stored on. Digital photography storage media includes CompactFlash cards and CDs.

Megabyte (MB) – A measurement of data storage equal to 1024 kilobytes (KB).

Megapixel – A measure of the size and resolution of the pictures that a digicam can produce - a megapixel is equal to one million pixels (or more accurately a million light sensors on the camera's CCD.

Memory Stick® — A memory card slightly smaller than a single stick of chewing gum. Like CompactFlash and SmartMedia, it is flash-based storage for your photos.

Digital Photography Glossary: N

NiMH – Nickel Metal-Hydride: a type of rechargeable battery that can be recharged many times. NiMH batteries provide sufficient power to run digital cameras and flashes.

Digital Photography Glossary: O

Optical Zoom - Optical zoom lenses can be adjusted to magnify an image (zoom in) or to capture a wide-angle shot (zoom out). Optical uses the full capability of the CCD, so it is superior to digital zoom.

Digital Photography Glossary: P

Pixel – Short for 'Picture Element': digital photographs are comprised of thousands or millions of them; they are the building blocks of a digital photo.

Point and Shoot - Simple digicams are referred to as 'point and shoot' cameras as the user just needs to aim and press the shutter release.

Portrait mode - This is a program exposure mode that optimizes the digital camera for taking portrait shots by widening the aperture to minimize depth of field.

Program exposure - An automatic camera setting where the metering system selectsand appropriate aperture setting and shutter speed to get the best performance out of the lens.

Digital Photography Glossary: Q - R

Red-eye – Refers to the red glow from a subject's eyes caused by light from a flash reflecting off the blood vessels behind the retina in the eye. The effect is most common when light levels are low, outdoor at night, or indoor in a dimly-lit room.

Resolution - The more pixels there are in a digital image, the sharper it will appear. This is the resolution. It is usually expressed as two figures representing the photo's height and width, such as 1200 x 1600 pixels.

RGB – Red, Green, Blue: the three colors to which the human visual system, digital cameras and many other devices are sensitive.

Digital Photography Glossary: S

Sensitivity – See ISO speed.

Serial – A method for connecting an external device such as a printer, scanner, or camera, to a computer. It has been all but replaced by USB and FireWire in modern computers.

Sharpness – The clarity of detail in a photo.

Shutter lag - There is often a delay between pressing the button and the camera taking the photo in digital cameras. This is called 'shutter lag'.

Shutter priority - Refers to a semi-manual mode that enables you to specify a shutter speed while the camera sets the appropriate aperture for the correct exposure.

Shutter speed – The camera's shutter speed is a measurement of how long its shutter remains open as the picture is taken. The slower the shutter speed, the longer the exposure time. When the shutter speed is set to 1/125 or simply 125, this means that the shutter will be open for exactly 1/125th of one second. The shutter speed and aperture together control the total amount of light reaching the sensor. Some digital cameras have a shutter priority mode that allows you to set the shutter speed to your liking. See also aperture.

Slow-sync Flash - This camera feature is ideal for night-time photography to, for example, illuminate subjects standing in front of dark buildings. The flash fires just before the shutter closes.

SLR - Stands for 'Single-Lens Reflex'. A mirror or prism reflects the light coming in through the lens to the viewfinder, so when you look through it you see exactly what the camera does.

Slow-sync flash - This feature fires the flash just prior to the shutter clsoing. It's ideal for night photography to illuminate subjects in front of darkened buildings.

SmartMedia™ — a wafer-thin, matchbook size memory card. This is also a flash-memory based storage medium.

Digital Photography Glossary: T

TIFF - Stands for 'Tagged Image File Format' and is often used for saving digital images. Unlike JPEGs, which can be compressed, quality is not reduced when the file is saved as a TIFF.

Digital Photography Glossary: U

Digital Photography Glossary: V

VGA - stands for 'Video Graphics Array'. This is normally the lowest resolution that computers use to display an image. The picture size is 640 x 480 pixels.

Digital Photography Glossary: W

Wide angle - In terms of lenses, wide angle means giving a large field of view. Examples of wide-angle photography are landscapes and street photography. It corresponds to a short focal length.

Digital Photography Glossary: X - Z

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