Glossary for Digital Photography

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Additive Primary color (see also RGB)- The RGB color model used by emitted imaging devices that allows white to be created by adding all colors, while black is the absence of all colors.

Aliasing- The noticeable repeated patterns, lines, or textures in any photographed or scanned subject that conflict with the pattern of an electronic sensor’s pixel arrangement. For example, diagonal lines represented by square pixels will produce jagged lines.

Anti-aliasing- The process used to remove “jaggies” or stair stepping in an image. Anti-aliasing smoothens diagonal lines by placing dots of an in-between tone in appropriate places.

Aperture (see also f-stop)- The opening in the lens that light passes through to expose the image sensor and thus make an image. The size of aperture is indicated by the f-stop number; the smaller the number, the bigger the opening.

Aperture Priority Mode- Usually denoted by “Av” or “A” on the command dial or menu of camera. It allows user to select the aperture while the camera automatically sets the shutter speed to obtain optimal exposure.

Archival Quality- The ability of a medium to resist deterioration over time. The term is often used to describe printed that resist fading and color changes.

Artifacts (or “Artifacting”)- Misinterpreted or extraneous digital information resulting from the technical limits of an imaging system. Artifacts alter pixel values, and are the results of flare, motion, compression, dust, scratches, and so on. Artifacts creat color faults or line faults that visibly impact the image negatively.

Aspect Ratio- The ration of length to width. This term can be used at many levels to describe an individual pixel, a CCD, an image, or a device such as computer monitor or television screen.

Bit- The smalles amount of digital information. Made up of a 1 or 0 representing an on or off state.

Bit Depth- Refers to the gray scale range of an individual pixel. A pixel with 8 bits oer color gives a 24-bit image (8 bits x 3 colors). 30- or 36-bit is billions of colors; 24-bit is 16.7 million colors; 16-bit is 65,535 colors; 8-bit is 256 levels of gray or color.  The bigger the bit depth,  the better the differentiation between colors.

Bitmap- Originally was the image file using the on or off bit to produce a black or white dot. Now it is more generally referred to the method of storing information that maps an image pixel bit-by-bit. Most image files are of this type including .bmp, .pcx, .pict, .tif, .jpg, and so on. When examined closely, user can see the line of pixels that creates edges that could be stair-stepped edges, or the “jaggies.”

Bleeding- The color value of one pixel unintentionally appearing in th e adjuacent pizel or pixels.

.bmp- Windows Bitmap file format that was created by Microsoft as the system standard format.

Brightness- One of the three dimensions of color (HSB). Brightness is the relative lightness or darkness from 0% black to 100% white.

Burst Rate- The number of images a camera can shoot in rapid sequence before it needs to pause and process the files, High burst rate are good for photographers who like to shoot fast-action subjects like sports.

Byte- Digital or computer measurement of storage, memory, file size or information made of 8 bits of information.

Calibration (see also Color Management System)- The method of adjusting scanners, printers, displays, and other devices to a defined standard to represent colors accurately. Color calibration is necessary for accurate WYSIWYG color management.

Card Reader- A device used to transfer data from memory cards to computer without the need to connect digital camera.

CCD- Charged Coupled Device, a light sensitive chip used for image gathering. In the normal condition, it is a grayscale device. To create color, a color Bayer pattern is laid down on the sensor pixels, using a color mask like RGBG (Red, Green, Blue and Green, where the extra green is used to create contrast in the image). CCD pizels gather the color from the light and pass it to the shift register for storage.

CMOS- Complementary Metal Oxide Semiconductor, an integrated circuitry having both digital and analog circuits fabricated on the same substrate allowing for controlling ASIC technology to be embedded into the chip design. Commonly used in computer designs for controllers, but now applied to light sensitive products such as image sensors in digital cameras.

CMYK- Cyan, Magenta, Yellow, and Black. Colors used in printing. It is also known as a reflective color since it is printed on paper or reflective films. Converting RGB file to CMYK files could cause color shifts. This is where calibration and color management is needed to make sure the printer prints what is shown on the display.

Color Fringing- A CCD artifact caused when color filtering arrays or patterns conflict with information scene.

Color Gamut- The extent or range of colors that can be produced or displayed by a particular device (such as a monitor or printer). Also a color model or color space used to describe visible colors used in images.

Color Management System (see also Calibration, CMYK, RGB)- A set of software utilities that help calibrate color on input and output devices like displays, printers, and scanners. Color management systems control the accurate conversion colors from RGB to CMYK, in printing and display.

CompactFlash Card- Rewritable, removable memory or function card developed by SanDisk in 1994. In contrast with SmartMedia, it has a built-in controller. In contrast with Microdrive, it is solid state, meaning there are no moving parts (electronics rather than mechanics do the work).

Compositing- Combining parts of two or more photographs (or other types of images) to create one final image.

Composition- The art of carefully designing an image and consciously deciding how to frame a scene of subject.

Compression- Software algorithms that reduce the number of binary digits in a digital file by eliminating redundant information. The resulting files are reduced in size.

Compression Ration- The ratio of the size of a compressed digital file to the original uncompressed digital file. Ratios between 15:1 and 8:1 are the most often used in digital cameras. Highest quality ratios are less than 5:1; non-lossy compression is 2:1 or less.

Continuous Tone- The smooth infinite gradation of colors or grayscale without banding.

Contrast- The relationship between the lightest and darkest tones that appear in an image. High contrast will produce an abrupt and sharp difference in tones, when low in the image will appear flat.

DCF- Design Rule for Camera File System, an industry standard for saving digital images. This not only determined the file type, but also sets the rule for naming the folder and file structure. It allows the conversion of uncompressed TIFF files into compressed JPEG files.

Density- The ability of a color or gray to stop or absorb light. The less light reflected or absorbed, the higher the density.

Density Range- The range from the smallest highlight dot the press can print to the largest shadow dot that can be printed. The amount of details that can be seen in the shadow (blacks) to the highlights (whites) of an image.

Depth of Field (DOF)- the distance in front of and beyond the subject that appears to be in focus. Precisely, the range of distances along the axis of an optical instrument, usually a camera lens, through which an object will produce a relatively distinct image.

Dithering- A method of simulating gradations or grays or colors by spacing the same colored dots or pixels different intervals.

Download- Describes the process of receiving data, usually via the internet or from another device such as digital camera to a computer.

Dot- The unit (size) printers use to describe the ink or toner places for printing. Dot can correspond to a pixel used to show an image or a group of pixels to produce a larger printer dot(s) to represent grays.

Dot Gain- The tendency in printing for dots to print larger than they should. The increased dot size causes darker tones or color, and an increase in the density of light reflected by the image. This is most pronounced when using poor quality papers, or when inks are absorbed and spread.

DPI- Dots Per Inch, a printing term that describes the number of dots per inch that are used to create an image. The smaller the size and g4eateer the number, te higher the geometric resolution of the printer. (Note: digital input devices such as scanners and cameras do not have a dpi but use pixels.)

DPOF- Digital Print Order Format, a format that enables images stored on memory cards to be accessed directly by supporting printers for a simpler printing solution.

Dye-Sublimation Printer- A type of printer in which dry colorants (usually on ribbons) are rapidly heated to a gas state then transferred to and solidified onto paper. Dye-sub printers can produce continuous tones that usually results in photographic quality images.

Dynamic Range- Usually referred to the ratio of contrast, tonal range, or density in an image between black and white. Loosely speaking, human eyes can usually recognize 11 exposure zones, while negative films can capture 9 zones and positive films (slide film) can only capture 5 zones. Digital image sensor varies depending on bit depth; typically an 8-bit sensor can capture 5 zones while a 14-bit sensor can capture 11 zones.

Emitted Color- The additive RGB color model used to produce colors on televisions and computer displays.

.EPS- Encapsulated Postscript, a file standard set by Adobe for printers, which is the mathematical definition of shapes, lines, color, and space. This is one of the most accurate ways to define a font or image and also add page description information to the files. .EPS images can be reduced or enlarged in size with no loss in quality.

EXIF- A new storage, compression file format used to store images on memory cards and digital cameras. EXIF files contain either JPEG or TIFF, and additional header information.

Exposure- The total amount of light received by a photosensitive surface (in digital, it is the image sensor in camera), expressed as the product of the degree of illumination (aperture) and the period of illumination (shutter speed).

File Format- The “language” in which the digital image is written. Tells an application how it should handle the data in the file to display it correctly.

Filter- An optical attachment placed on the front of the lens. It is used to protect lens, correct color, adjust exposure, create a special effect, or enhance an image by absorbing part(s) of the visible light spectrum. Many effects can now be reproduced in image editing software and thus known as digital filters.

Firmware- An often-used micro-program or instruction set stored in ROM. Usually referred to the ROM-based software that controls a unit. Firmware is found in all computer-based products from digital cameras to other peripherals. 

Focal Length (35 mm equivalent)- Different effective focus with which lenses function depending on the size of the image-sensor chip being used. Because the size of the image-sensor chips in digital cameras vary widely, manufacturers base their listings of focal length on the size of a classic 35mm film frame.

f-stop- Sometime referred as “f number, “ it is the measurement of lens aperture. More precisely, the ratio of the focal length of a lens or lens system to the effective diameter of its aperture. Therefore, the smaller the number, the bigger the opening

Gamma- The mid-tone contrast in an image or on a display. Gamma values will affect the balance of the midtowns without any effect on pure white or pure black.

.GIF- Graphic Interface, a file format designed by CompuServe for using images online. This is a 256 color (8-bit) image.

Gigabyte (or GB)- A unit of data measurement equal to a billion bytes. The storage capacity of computer hard drives and memory cards is often described using this unit of measurement.

Grayscale- A color mode hat consists of only one channel, black.

Highlight- The lightest area in an image

Histogram- A graphic representation of the tones in an image. This can be viewed from within most image-editing software and on the LCD screens of many cameras when reviewing images.

HSB- Hue, Saturation, and Brightness, the color model that most closely resembles the human perception of color.

Hue- One of the three dimensions of color (HSB), the wavelength of light reflected from or transmitted through an object, seen as the visible spectrum. Red, yellow, blue, and so on are the names of hues.

ICC- International Color Consortium, device dependant color profiles used to manage color in the captured editing and printing or digital images.

Image Editing Software- Software that allows user to view and alter digital images.

Image Sensor (see also CCD and CMOS)- The part of the camera that captures the image. Its unique qualities determine that resolution of the images captured on it.

Indexed Color- Reduced color mapping, 8 bits or less, done to reduce images to their smallest size. Commonly used for images placed on home pages of the internet.

Inkjet Printer- A type of printer in which fine droplets of ink are squirted through very small nozzles onto paper

Interpolation- The digital process of inserting extra pixels into a digital image to increase its size or resolution.

ISO- International Standards Organization, a committee of representative from different countries responsible for the establishment of consistent global standards. ISO products include film speeds, computer standards such as JPEG, and so on.

ISO Setting (on digital cameras)- How sensitive to light the image sensor is set to be. Higher ISP settings allows user to work more easily in low light but produce more noise, which could affect the image quality.

“Jaggies”- common term for the stair-stepped appearance of a curved or angles line in digital imaging. The smaller the pixels are the grater their number, the less apparent the “jaggies.” Also known as pixelization. 

.jpg, JPEG- Joint Photographic Expert Group, the de facto ISO standard for image compression in digital imaging devices. There are several versions of JPEG, such as JFIF. JPEG uses 8x8 pixels and compresses the information to its lowest common value based on a set ratio.

Kilobyte (KB)- A measurement of file size that equals to 1024 bytes.

LCD- Liquid Crystal Display, widely used in computer monitors, TV screens, and digital camera displays.

Lens, Fixed (or Prime)- The type of lens that offers only one view angle.

Lens, Zoom- The type of lens that lets user choose between different view angles. Users can zoom in (using a telephoto setting) to get a closer view or zoom out (using a wide angle setting) to see a broader view.

Light Meter- An instrument that measures the smount of light and recommends an appropriate exposure setting. Digital cameras usually have a reflective light meter built-in that measures amount of light reflected off a subject. External light meters (handheld device) usually use incident metering, which measures the amount of light shed on the subject.

LPI- Line Per Inch, refers to the rows of dot in half tones or the frequency of the screen. Most newspaper print at 85 lpi, while a magazine or book will use 133 lpi.

Macro photography- Close-up shots that fill up the entire frame with a small subject. Usually the camera lens has to be just a few inches from the subject, but is still able to focus precisely. Most compact digital cameras have a built-in macro setting, and digital SLR cameras is best to pair with macro lenses to achieve the effect.

Manual Mode- A camera setting where the user makes all the decisions abou exposure, focus, flash, white balance, etc.

Megabyte (MB)- A measurement of file size that equals to 1024 KB (or 1,048,576 bytes).

Megapixel- One million pixels. Commonly used measurement unit to describe the resolution of image sensor in digital cameras.

Memory Card- Devices used to store digital images after they are captured by the camera’s sensor.

Memory Stick- A removable flash memory card format launched by Sony in October 1998. Also used in general to describe the whole family of Memory Sticks. This family includes the Memory Stick PRO, a revision that allows greater maximum storage capacity and faster file transfer speeds; Memory Stick Duo, a small-form-factor version of the Memory Stick (including the PRO Duo); and the even smaller Memory Stick Micro (M2). In December 2006 Sony added the Memory Stick PRO-HG, a high speed variant of the PRO, to be used for high definition still and video cameras.

Metering- Evvaluating the amount of light in a scene to determine the correct exposure.

Microdrive- A type of memory card that is actually a miniature hard disk designed to fit in a Compact Flash (CF) Type II slot. However, they may consume more power than flash memory and therefore may not work in some low-power devices (e.g. handheld computers).

Midtones- All of the tones in an image that are neither pure white nor pure black.

MultiMediaCard (MMC)- A flash memory memory card standard developed in 1997 by Siemens AG and SanDisk. MMC is about the size of a postage stamp: 24 mm x 32 mm x 1.4 mm. MMC originally used a 1-bit serial interface, but newer versions of the specification allow transfers of 4 or sometimes even 8 bits at a time. They have been more or less superseded by SD card (see also Secure Digital), but still in current market because MMCs can be used in most devices which support SD cards.

Noise- A grainy appearance in digital images that occurs when using high ISP setting that caused unwanted or uncontrolled electronic buildup in the image sensor. Sometimes noise may be added intentionally using image-editing software to create a desired look.

Panoramic Image- Long, narrow photographs that often show as much as a 360-degree view of a scene.

Pantone- The industry standard color management system for printer color reproduction.

.PDF- Portable Document Format, a cross-platform file designed by Adobe. Images, text, graphics, or even movies can be browsed on different computers with the Acrobat Reader.

Pixel- Short for “Picture Elements,” the smallest discrete part of a digitized or digital image. Also used in measuring  image size and geometric resolution,  

Program Mode- The program mode (usually indicated by a “P”) allows user to control some setting (like white balance, ISO, etc.) but not as man as the fully manual mode.

Red-Eye Reduction- Red-eye occurs when the lens and light source (usually an on-camera flash) are directly in line with the subject’s eyes. To combat this effect, most cameras now include a red-eye reduction setting. When this setting is used, an initial burst of light closes down the pupil, preventing the second burst of light from reflecting off the retina and back into the camera when the shutter is released. If red-eye still occurs, user can fix it easily in most image-editing software.

Reflected Color (see also CMYK)- The color model hat allows people to see colors. The visible light striking an object that absorbed all colors not seen while reflecting the visible colors.

Resolution- The sharpness, tonal range and color accuracy of an image. The pixel count determined the geometric resolution and tonal dynamic range of the image. The optical resolution of lens determines the clarity, focus and contrast of the information provided to the image capture material (in digital camera, the image sensor).

Retouching- Using image-editing software to reduce or correct problems in an image that were unnoticed or impossible to correct at the time the image was taken.

RGB- Red, Green, and Blue, the color model of computers. Monitors and digital cameras use these colors to create all the colors seen on the monitors and saved in files. Green gives the color green but is also used for contrast control. RGB is an emitted color set, which may appear differently when printed.

Saturation-  One of the three dimensions of color (HSB), the measure of the purity of a color. De-saturated color is 0% black.

Secure Digital (SD)- A flash memory card format developed by Matsushita, SanDisk and Toshiba for use in portable devices, including digital cameras, handheld computers, PDAs and GPS units. As of 2007, SD card capacities range from 8 MB to 16 GB. Several companies have announced SD cards with 32 GB. Cards with 4-32 GB are considered high-capacity.

Shadow- The darkest areas in your image

Sharpen- To increase the apparent focus o an image (or areas of an image) to enhance image details.

Shutter Lag- A delay between when you push the shutter button on a digital camera and when the photo is actually taken.

Shutter Priority Mode- In the mode (commonly indicated by “Tv” or “S”), user select the shutter speed and the camera selects the best aperture setting to match the brightness of the scene.

Shutter Speed-  How long the camera’s shutter remains open to make an exposure. Shutter speed is usually measured in fraction of a second. Therefore, the larger the number shown on the camera, the shorter and faster the shutter speed. Choose a short shutter speed to freeze moving subjects, or a long one to blur the motion in the image.

SmartMedia- A type of memory card for file storage that looks like a miniature floppy disk.

Subtractive Primary Color (see also CMYK)- The color model that allows the absorption of light, reflecting only the visible color.

TIFF (file extension “.tif” or “.tiff”)- Tagged Information File Format, a file format that employs lossless compression to reduce the memory required to store images. This preserves the visual quality of the image.

Tonal Range- The maximum range of tones visible in any image or reproduction.

Twain- An acquire interface developed by a consortium of software developers as a standard for communications between scanners, imaging devices, and some digital cameras and the computer software.

Viewfinder- A window on the camera through which user sees to compose images.

White Balance- The ability of digital cameras to adjust color based on the lighting situation of a shot. The cameras use white as a reference point and adjust the color balance to give as true as possible a white, correcting all the other colors by doing so. Some cameras may offer preset modes such as sunny day, fluorescent, cloudy, incandescent, and so on. Advanced cameras also offer manual mode in which user may use a white card as reference for accurate white balance control or enter a precise color temperature number for the camera to adjust accordingly.

Workflow- An individualized procedure followed when uploading, backing up, editing, and archiving images. A good workflow should be designed to safely and efficiently process digital files.

WYSIWYG- “What you see is what you get,” refers to accurate screen images to print out. 

xD-Picture Card- A type of flash memory card used mainly in digital cameras. xD originally stood for “extreme Digital.” Developed by Olympus and Fujifilm and manufactured by Toshiba Corporation and Samsung Electronics, xD cards were introduced into the market in July 2002. They are now sold under many other brands, including Kodak, SanDisk, and Lexar. Used mainly in Olympus and Fujifilm digital cameras, Olympus digital voice recorders, and Fujifilm MP3 player, xD cards are available in capacities of 16 MB, 32 MB, 64 MB, 128 MB, 256 MB, 512 MB, 1 GB, and 2 GB. xD cards have dimensions of 20 mm × 25 mm × 1.78 mm.

Zoom, Digital- Usually seen on compact point-and-shoot cameras, this is image enlargement that is provided by software or rather than the lens. This reduces the image quality and is usually defaulted as off.

Zoom, Optical- Image enlargement or change of view angles provided by the mechanical qualities of the lens. This usually does not affect image quality.