Anti-aliasing makes text look smooth in bitmap graphics.

A small, circular opening inside the lens 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. The aperture and shutter speed together control the total amount of light reaching the sensor. A larger aperture passes more light through to the sensor.

Some cameras allow you to manually set the aperture and the camera automatically chooses the suitable shutter speed to correctly expose the image.

These are blurry distortions which appear when files are compressed aggressively and image quality is degraded. Often seen in JPEG files which are highly compressed.

The basic unit in a binary numbering system. A single bit is expressed in the base 2, either on or off.
Imagine using bits of data to express gray scale. Progressive levels display are expressed as increasing powers of 2. In a one bit system (21) there would only be white or black.
A four bit system is 24 (16 gray scale levels) where a six bit system is 26 (64 levels of gray). The more gray, the better the picture.

This refers to the grey scale range of an individual pixel. A pixel with 8 bits per colour gives a 24 bit image (8 bits X 3 colours is 24 bits). CCD sensors are coloured in a pixel by pixel method.

• 30/32 bit colour is billions of colours
• 24 bit colour resolution is 16.7 million colours
• 16 bit colour is 65,536 colours.
• 8 bit colour is 256 colours
• 8 bit grey scale is 256 shades of grey
• 1 bit is black or white.

The method of storing information that maps an image pixel, bit by bit. There are many bitmapped file formats. eg. .bmp, .pict, .tif, .gif, .png.

File format extension for Windows bitmap images. BMP images can range from black and white (1 bit per pixel) up to 24 bit colour (16.7 million colours).

The common name used for any Internet access program. eg. Internet Explorer, Firefox, Safari, Opera, Google Chrome.

Any open window or web page in your Internet access program.

A unit of measure equal to 8 bits of digital information. The standard measurement unit of a file size. See also Kilobytes, Megabyte and Gigabyte.

• 1000 Bytes of computer information = 1 Kilobyte
• 1,000,000 Bytes of information (or 1000 kilobytes) = 1 megabyte
• 100,000,000 Bytes of computer information = 1 Gigabyte.

Computer assisted learning.

This is the name given to either one of the red, green or blue ‘layers’ which make up a digital image. Image-editing software allows you to view each layer separately for editing.

A common type of digital camera memory card. There are two types of cards, Type I and Type II. They vary only in their thickness, with Type I being slightly thinner. Depending on size they can hold 100s or 1000s of photographic images.

This is used to describe the different colour of light depending on its source. Colour temperature is measured in degrees K (Kelvin). During the course of a day, light temperature can range from red (2000k) – sunrise and sunset – to blue/white (9000k) around mid-day. Artificial light sources (eg, fluorescent and tungsten bulbs) also have their own colour temperatures. On a camera this is controlled through white balance adjustments.

The process of reducing the size of a digital file, usually through software. This speeds processing, transmission time and reduces storage requirements. Compression can be ‘lossless’ where image quality is maintained or ‘lossy’ where higher levels of compression will result in degradation of the image.

The arrangement of the elements within a photograph: the main subject, the foreground and background, and supporting objects. See ‘rule of thirds’.

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

Stands for Cyan Magenta Yellow Black. 4 colour system used in professional colour printing and for colour laser printers. Cyan, Magenta, Yellow, Black; These are the printer colours used to create colour prints. Most Colour Printers, Ink-Jet, Laser, Dye-Sublimation, Thermal, and Crayon printers use these as their printer colours. (This is one of the colour management problems for computers. Converting RGB files to CMYK files causes colour shifts.) When used by a printer the CMYK is also known as a reflective colour since it is printed on paper, or reflective films

This refers to the area in front of and behind the subject of a photograph that remains in focus. Depth of field is controlled by focal length of the lens, aperture setting, shutter speed and distance from the lens to the subject.

A camera that captures the photo not on film, but in an electronic imaging sensor that takes the place of film. May be compact (aimed at home users) or SLR (single lens reflex) aimed at professional photographers.

A digital image is a representation of a two-dimensional image using binary code ie. ones and zeros. Depending on whether or not the image resolution is fixed, it may be of vector or bitmap type. The term ‘digital image’ usually means bitmap or raster images.

Digital zoom (as opposed to optical zoom) uses interpolation to ‘blow up’ or enlarge the existing image electronically so it appears that you are zooming in on the subject. The result will degrade the quality of the image and is likely to be pixelated, depending on how much zoom is used. The effect is the same as cropping a photo and enlarging it to fill the space of the original uncropped image. Avoid using digital zoom when possible.

Measure of resolution for output devices such as printers. 300 dpi minimum is usually required for a printed page. Not to be confused with PPI.

Encapsulated postscript file extension. A file format often used by graphic designers and commercial printers to get high quality print. Used for capturing precise image and text information.

Exchangeable Image File: 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.

The combination of settings used to take a photograph with a camera. Settings include shutter speed, aperture and white balance. Automatic exposure will work out the best settings for you. Manual or semi-automatic exposure allows the user to control the settings. eg. 1/60 second at F8.

A number that indicates the relative size of the opening of the lens (aperture) and written, for example, as f/16. Because the number is obtained by dividing the focal length of a lens by it’s effective aperture, the larger the aperture, the smaller the f-number.

The way in which a digital image is saved to a camera’s storage card or computer hard drive.

The file size of an image is proportional to its resolution. The higher the resolution, the bigger the file size. File size is different from image size.

A flash technique used to brighten deep shadow areas, typically outdoors on sunny days. Some digital cameras include a fill flash mode that forces the flash to fire, even in bright light.

A very fast external bus that supports data transfer rates of up to 400 Mbps. Firewire was developed by Apple and falls under the IEEE 1394 standard. Other companies follow the IEEE 1394 but have names such as Lynx and I-Link.

Name commonly used to describe storage cards for digital cameras.

A very fast external bus that supports data transfer rates of up to 400 Mbps (megabits per second).

The distance, usually given in mm, between the optical centre of a lens and the point at which rays of light from objects at infinity are brought to focus. In general, the greater the focal length, the smaller and more magnified the part of the scene, it includes in the picture frame.

Graphic Interchange Format. GIF is suitable for images with 256 colours or less. The format allows transparency in images by selecting and defining area to be transparent eg. on web page so that the background colour of the web page shows through. The primary use is on the Internet and other on-line services. It supports up to 256 colours or 8 bit imaging.

A photo made up of varying tones of black and white (including 256 tones of grey).

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. The horizontal axis represents the tones from pure black (0) on the left to pure white (255) on the right. The vertical axis represents the number of pixels with each tone.

The brightest parts of a photo.

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, remove red-eye and much more.

This is the name of the method used to increase the size of a digital image by adding more pixels. Small amounts of interpolation can be quite successful. However, use with care! Too much will create artefacts and jaggies (pixels with a blocky appearance).

In film photography (pre-digital photography age), ISO indicates the light sensitivity of the film. The higher the ISO, the faster or more sensitive the film. The same applies to digital ‘film’. ISO is used to describe the output signal generated by a camera’s sensor. By adjusting the signal, a higher or lower ISO setting can be used. Normal conditions make ISO 100 suitable, while in poor light conditions ISO can be set to 400, 800 or even higher. Very high ISO settings however can lead to noise (graininess).

When examined closely a bitmapped image will show a line of pixels that create edges. Because they are made up of individual pixels they form a slightly rough or jaggy edge. Anti-aliasing is often used to try to smooth the edges for better viewing on screen.

A standard for compressing image data developed by the Joint Photographic Experts Group, hence the name JPEG. It is referred to as a lossy format, which means some quality is lost in achieving JPEG’s high compression rates. 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. JPEG is compatible with most imaging and playback devices.

An amount of computer memory, disk space, or document size consisting of approximately one thousand bytes. Actual value is 1024 bytes.

Layers are used in many image-editing applications. Very useful for applying effects or making adjustments on an image. Changes can then be made easily by editing or deleting layers.

Liquid Crystal Display: a low-power monitor often used the rear and/or top of a digital camera to display settings or the photo itself.

A method of image compression where there is no loss in quality when the image is uncompressed. The uncompressed image is mathematically identical to its original. Lossless compression is usually lower in compression radio than lossy compression.

A method of image compression where some image quality is sacrificed in exchange for higher compression ratios. The amount of quality degradation depends on the compression algorithm used and a user selected quality variable.

A unit of measure of stored data equaling 1,024 Kilobytes, or 1,048,576 bytes.

One million pixels or more. The more pixels that exist in an image the higher the resolution and therefore the greater the detail in the image.

Removable storage card that can be inserted into the camera to hold images. When the card is full it can be removed and another card inserted. The memory is non-volatile-m ie, images are not lost when removed from the camera. The image can later be downloaded from the card, and when the images are erased from the card it is ready to be reused. Examples include compact flash, secure digital, memory stick (Sony cameras) and XD.

This is the method cameras use to determine correct exposure. ‘Evaluative’ metering measures the exposure for the whole scene, ‘centre-weighted’ metering measures the entire scene but gives more weight to the centre of the frame, and ‘spot’ metering measures the correct exposure only for the subject in the centre of the frame.

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.

A form of artefact which makes an image grainy or blotchy. Usually caused by using high ISO settings in low light conditions on a camera with a small sensor.

A company that receives digital photos uploaded to its Web site, prints them, then sends the prints back by mail or courier.

Refers to reducing the file size of a digital image by compression and/or reducing the number of pixels so that the image is suitable for using on the Web.

Portable Document Format. This is a widely used file format which captures all the elements of a printed document as an electronic image that you can view, navigate, print, or forward to someone else. PDF files are created using Adobe Acrobat. To view and use the files, you need the free Acrobat Reader, which you can easily download. Once you’ve downloaded the Reader, it will start automatically whenever you want to look at a PDF file. PDF files are very useful for documents such as magazine articles, product brochures, or flyers in which you want to preserve the original graphic appearance online. A PDF file contains one or more page images, each of which you can zoom in on or out from. You can page forward and backward.

Picture Element: digital photographs are comprised of thousands or millions of them; they are the building blocks of a digital photo. Each pixel has specific colour and tonal values.

Portable Network Graphics. Developed as a patent-free alternative to GIF, the Portable Network Graphics (PNG) format is used for losslessly compressing and displaying images on the World Wide Web. Unlike GIF, PNG supports 24-bit images and produces background transparency without jagged edges; however, some older versions of Web browsers may not support PNG images. The PNG format supports grayscale and RGB colour modes with a single alpha channel, and Bitmap and indexed-colour modes without alpha channels. PNG uses the saved alpha channel to define transparency in the file.

PPI [spoiler /(show info)/ /(hide info)/]
Pixels Per Inch. This is the standard of measurement that governs the resolution of a digital image.

Adobe Photoshop file. A sophisticated software program, produced by Adobe Systems, for editing and processing of images. Files tend to be very large in size and do not use any form of compression so that quality and detail are maintained. Photoshop images are often built up in layers which can be edited separately before exporting them to other formats for different purposes.

is a multimedia framework developed by Apple, capable of handling various formats of digital video, media clips, sound, text, animation, music, and several types of interactive panoramic images. Available for Mac OS and Microsoft Windows operating systems, it provides essential support for software packages including iTunes, QuickTime Player (which can also serve as a helper application for web browsers to play media files.

A digital file made up of pixels.

Red-eye
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.

RAW images can be shot and saved on higher end cameras. Unlike JPEG or TIF files which are subject to in-camera processing, RAW files are unprocessed and only contain the information captured by the sensor. They need special software to download and edit them. The benefit is that they can have more effective and powerful adjustments made than any other file type. However they take up a lot more space on a memory card than the equivalent number of files saved as JPEG.

The appearance of deep red dots in the eyes of human and animal photographic subjects. Red-eye is is caused by the flash reflecting off the retina in their eyes. It can be prevented by adjusting the camera angle, improving the lighting, being sure the subject does not look straight at the flash, or with a redeye-reducing pre-flash. The pre-flash causes the subjects’ pupils to contract, reducing the visible retina and thus the possibility of light reflecting from it.

Refers to the sharpness and clarity of an image. The term is most often used to describe monitors, printers, and bitmapped graphic images. In relation to printers, the resolution indicates the number of dots per inch. For example, a 300-dpi (dots per inch) printer is one that is capable of printing 300 distinct dots in a line 1 inch long. This means it can print 90,000 dots per square inch. For computer monitors, the screen resolution signifies the number of dots (pixels) on the entire screen. eg. a 640 x 480 pixel screen is capable of displaying 640 distinct dots on each of 480 lines, or about 300,000 pixels. This translates into different ppi measurements depending on the size of the screen. eg. a 15-inch VGA monitor (640 x 480) displays about 50 dots per inch. Printers, monitors and scanners are often classified as high resolution, medium resolution, or low resolution.
Standard resolutions for computer screens are: 640 x 480 (older and less common now), 800 x 600, 1024 x 768 (most common), 1280 x 1024 and 1600 x 1200 pixels. The higher the resolution the finer the image detail that can be seen.

The number of dots per inch (DPI) or pixels per inch (PPI)used to display an image on a display device (monitor) or in print.

Stands for Red Green Blue. Used for viewing images on screen, inkjet printers and scanners.

The rule of thirds offers guidelines for good composition in photography and art. Imaginary lines are drawn dividing the image into thirds, both horizontally and vertically. Important elements of the composition are placed where these lines intersect. The best place to put main objects are a third of the way up, or a third of the way in from the left or right. Using the Rule of Thirds helps produce nicely balanced pictures which are easy on the eye. When the rule of thirds is broken, eg if an object is right in the middle, right at the top, right at the bottom it tends to produce an uncomfortable composition.
The rule of thirds is a guideline; it is not set in stone, and may often be broken for specific effect.

The size of the rectangular grid of pixels displayed on a monitor. eg. 640 x 480, 800 x 600, 1024 x 768.

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.

A device that captures an image for your computer and converts it to a digital form that your computer can display, edit store and output. A scanner can be used for a wide variety of application, such as incorporating artwork or photos into documents, scanning printed text into your word processor to eliminate retyping, scanning faxed document into a database for storage, and adding images to multimedia productions.

A semi-automatic setting which allows you to set the shutter speed manually. The camera then automatically sets the correct aperture for the image to be taken.

Memory card about the size of a postage stamp that weighs approximately two grams; available with storage capacities as high as 128MB. Secure Digital memory is gaining favor in all types of personal electronics devices.

Higher end cameras aimed at professional and semi-professional photographers. Prior to capture the image is viewed and framed directly through the lens rather than through a viewfinder or on an lcd screen. Non-SLR cameras tend to be referred to as ‘compact’ cameras. They are usually much smaller than SLR cameras.

File created by Macromedia Flash (now Adobe) often used to upload to the Web. Often contain animated graphics and interactivity.

A small version of a photo. Image browsers commonly display thumbnails of photos several or even dozens at a time. In Windows XP’s My Pictures, you can view thumbnails of photos in both the Thumbnails and Filmstrip view modes.

Tagged Image File Format. A popular image file format supported by the majority of image-editing programs running on a variety of computer platforms. Much larger size than JPEG format. Suitable for printing at high quality. Unsuitable for the Web.

This is the term used to describe the process of increasing the resolution of an image through increasing the number of pixels. Extreme care must be taken for this process and is only recommended as a last resort if a larger image is not available.

Universal Serial Bus: a protocol for transferring data to and from digital devices. Many digital cameras and memory card readers connect to the USB port on a computer. USB card readers are typically faster than cameras or readers that connect to the serial port, but slower than those that connect via FireWire.

Vector graphics is the use of geometrical elements such as points, lines, curves, and shapes or polygons, which are all based upon mathematical equations, to represent images in computer graphics. Vector graphics formats are complementary to raster graphics, which is the representation of images as an array of pixels, as it is typically used for the representation of photographic images. There are instances when working with vector tools and formats is best practice, and instances when working with raster tools and formats is best practice. There are times when both formats come together. An understanding of the advantages and limitations of each technology and the relationship between them is most likely to result in efficient and effective use of tools.

View finder [spoiler /(show info)/ /(hide info)/]
Either an optical or electrical display used to frame in the camera.

Virtual learning environment. Examples are Blackboard, WebCT, Elearn, Moodle. A vle is the web area where you access and interact with learning resources.

Virtual reality.

When a photo or graphic is produced its file size is often too large for use on a website. Optimization is acheived by reducing the size of a large file by converting it to GIF or JPEG format.

Colours in which will display accurately and consistently on every version of internet browser (Internet Explorer, Netscape Navigator, etc.) or computer platform (PC or Mac). There are 216 web safe colours.

A function on the camera to compensate for different colors of light being emitted by different light sources. The perceived colour of an object is affected by the colour of the lighting under which it is viewed. The human brain is able to detect and compensate for such changes in perceived colour. As a result, a white object will look white to humans whether viewed in sunlight or under overcast skies, or indoors under incandescent or fluorescent lighting. A digital camera must emulate the human brain and adjust colours accordingly to lighting so that colours appear white when viewed directly also appear white in the final photograph. This adjustment is called “White Balance”. Most video systems use a “white balance” to aid in overcoming colour problems created by adverse lighting conditions. The colour balance assumes that under normal conditions, that if a white object can be made to look white, then the remaining colours will be accurate too. If the original lighting is not close to the proper colour temperature (typically daylight), the “white balance” may reproduce white at the expense of other hues. Most digital cameras feature automatic white balance, this means that the camera looks at the overall colour of the image and calculates the best-fit white balance, however these systems are often fooled (especially if taking a photograph dominated by one colour, say green). Modern “prosumer” digital cameras also allow “white preset” which simply means measuring the white point from a white sheet of paper or card (or nearby wall), the camera will then record that temperature and use it to correct all images until you reset it.

Whereas an optical zoom uses the optics (lens) of the digital camera to move you closer to your subject, a digital zoom simply uses the existing image and enlarges it digitally.Enlarging the image digitally reduces picture quality, and should therefore usually be avoided. However, a judicious use of digital zoom may sometimes yield images that are of quite acceptable quality. So, use with caution.What is important when comparing digital cameras is the optical zoom. Digital zoom can always be achieved later in an image editing software, such as Photoshop, so should not really be a determining factor when choosing a digital camera.