Digital Photography Glossary

Digital Video Equipment Introduction

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A/D Converter (Analog to Digital) A device that converts analog information (a photograph or video frame) into a series of numbers that a computer can store and manipulate.
Angle of View The amount of a scene that can be recorded by a particular lens. This is determined by the focal length of the lens.
Anti-aliasing The process of reducing stair-stepping by smoothing edges where individual pixels are visible.
Aperture The maximum size of the hole through which light enters the camera.
Artifact(ing) Distortions or excess noise which are caused by the sensor, the optical system or image processing (such as compression).
Aspect Ratio The ratio between the width and height of an image or image sensor.
Attachment A file sent along with an e-mail message so that it can be viewed or saved by the recipient.
Automatic Exposure A feature where the camera automatically adjusts the aperture or shutter speed or both for the proper exposure.
Automatic Flash A flash unit with a light-sensitive cell that determines the length of the flash for proper exposure by measuring the light reflected back from the subject.
Autofocus A system that automatically focuses the camera lens.
Averaging See Matrix Metering.
AVI A video format used by Microsoft Windows®.

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B&W Black and white.
Back Lit The subject is heavily lit from behind which generally causes it to be underexposed.
Banding An artifact of color gradation where graduated colors are reduced to larger blocks of a single color.
Barreling A distortion which occurs with wide-angle zoom, in which straight lines at the edges curve toward the center, giving the image a barrel-like appearance.
Bit (BInary digiT) The smallest unit of computer memory.
Bit Depth The color or gray scale of an individual pixel. A pixel with 8 bits per color gives a 24 bit image. (8 Bits x 3 colors is 24 bits.) 24 bit color resolution is 16.7 million colors.
Bitmap A method of storing information that maps an image pixel bit by bit.
Blooming A visual effect caused by overexposing a CCD sensor, which can cause distortions of the subject and/or color.
BMP An uncompressed bitmapped file format (BMP) used with Microsoft Windows.
Brightness The value of a pixel in an electronic image, representing its lightness value from black to white. Usually defined as brightness levels ranging in value from 0 (black) to 255 (white).
Buffer A temporary storage area usually held in RAM and used as a temporary holding area for data.
Burst Mode The ability to rapidly capture images as long as the shutter button is held down.
Byte A group of 8 bits, the basic unit of information for the computer.

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Capture A term used in digital imaging meaning " to photograph". The term is used to differentiate the method by which the image is made. As the word "photograph" is closely associated to film photography, "capturing" is applied to specify a digital sensor is used."
Card A sealed package containing storage chips or other electronic devices for use in a card slot on a camera, printer, computer, or other device.
Card Reader A device, which allows your computer to directly, read flash memory cards. See also PCMCIA and PC Card
CCD (Charge-coupled device) An image sensor that reads the charges from the sensor's photosites one row at a time.
CDR (CompactDisc Recordable) A recordable CD which can be written once, which holds 650~700 MB of digital data.
CDRW (CompactDisc ReWriteable) A CD-R that can be erased and re-used many times, which holds about 450 MB of data.
Center Weighted An autoexposure system that uses the center portion of the image to adjust the overall exposure value. See Spot Metering and Matrix Metering
Chromatic Aberration A fringing effect around the edges, which is caused by lens not focusing correctly.
CIFF (Camera Image File Format) A method of digital camera image storage used by many camera makers.
CMOS (Complementary Metal Oxide Semiconductor) An imaging system used by digital cameras.
Codec (Compression and Decompression) Compresses information so that it can be sent across a network faster, and decompresses information received via the network.
Color Balance The accuracy with which the colors in the image match those in the original scene.
Color Correction The process of correcting or enhancing the color of an image.
Color Depth The number of bits assigned to each pixel in the image and the number of colors that can be created from those bits. True Color uses 24 bits per pixel to render 16 million colors.
Color-Filter Array The filter dyes placed directly over each pixel on the chip surface (CCD, CMOS).
CompactFlash (CF) The most common type of digital camera flash memory storage. There are two types:
  • CF Type I: the original 5mm high card
  • CF Type II: cards and devices that are 9mm high. Type I devices are all solid state but Type II devices include the new IBM Microdrive, a miniature, rotating hard drive. and check here: Flash Memory Cards/Readers
  • CF Type III: used in double-height slots only.
COM port A serial communication port which support the RS-232 standard of communication.
Compression The process of reducing the size of a file. Compression is either lossless or lossy.
Continuous Autofocus An always-on autofocus system.
Contrast A measure of rate of change of brightness in an image.

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Dark Current
Dark Noise
The charge accumulated by pixels while not exposed to light. Normally, this charge is reduced or eliminated prior to capturing a picture.
Decompression The process of restoring the contents of a compressed file.
Depth of Field The distance between the nearest and farthest points that appear in acceptably sharp focus in a photograph. Depth of field varies with lens aperture, focal length, and camera-to-subject distance.
Diaphragm The adjustable aperture of a lens, which controls the amount of light passing into the camera and may be in front of, within or behind the lens.
Digital Zoom A digital magnification of the center 50% of an image. Digital zooms increase the apparent image size by interpolation. They do not increase the amount of image information.
Digitization The process of converting analog information into digital format.
Diopter Correction An adjustment on the viewfinder of a camera, allowing someone to adjust the viewfinder to their vision and removing the need to wear their glasses when looking through it. Diopter adjustments cannot compensate for all vision problems, only near and far sightedness can be compensated
Direct Vision Cameras using an optical viewfinder.
Distortion A defect in an image caused by the lens, such as barreling and pincushioning.
Download Transfer data from a device to a computer using a cable connection.
DPI (Dots Per Inch) A measurement value used to describe either the resolution of a display screen or the output resolution of a printer.
DPOF (Digital Print Order Format) A format which allows you to embed printing information on your memory card. Select the pictures to be printed and how many prints to make. Some photo printers with card slots will use this info at print time.
DRAM (Dynamic Random Access Memory) A type of memory that is lost when the power is turned off.
DRAM Buffer Fixed memory used for image processing before the image is stored. Cameras with a burst mode have much larger DRAM buffers. This also makes them more expensive.
Dye Sub
Thermal Dye Sublimation
A printing process where the ink is thermally transferred to printing media. Usually expensive but providing extremely high quality. Thermal dye printers require special paper.
Dynamic Range A measurement of the accuracy of an image in color or gray level. More bits of dynamic range results in finer gradations being preserved.

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EPP (Enhanced Parallel Port) A high-speed, bi-directional printer port on modern computers used by some digital cameras and scanners.
E-TTL (Evaluative-Through The Lens) An exposure system that uses a brief pre-flash before the main flash to calculate the exposure index (used by Canon®).
EXIF Embedded camera and exposure information that a digital camera puts in the header of the JPG files it creates. Many programs can read and display this information.
Export To print, compress or save a data file using a particular file format or function.
Exposure The amount of light that reaches the image sensor. Exposure is controlled by a combination of the lens aperture and shutter speed.

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f numbers
f-stops
A numerical designation (f/2, f 2.8, f3 etc.) indicating the size of the aperture.
Firewire see IEEE-1394
Fixed Focus A lens, which is preset to a given focus, distance in order to provide the maximum depth of field.
Flash A flash supplies additional light to compensate for low lighting, back-lighting and other lighting issues.
Flash Memory Card A card containing chips that store images.
Flash Memory Reader An accessory that attaches to your computer by cable and allows your computer to read directly from a flash memory card.
Flash RAM (Flash Random Access Memory) Rewritable memory often used for temporarily storing information such as digital pictures.
Flat Bed Scanner An optical scanner in which the original image remains stationary while the sensors pass over or under it.
Focal Length The distance from the optical center of the lens to the image sensor when the lens is focused on infinity, usually expressed in millimeters.
Focus The process of bringing one plane of the scene into sharp focus on the image sensor.
FPX (FlashPiX) An image format that contains a number of resolutions, each of which is broken into tiles that can be edited and displayed independently.
Frame One of the still pictures that make up a video.
Frame Grabber A device that lets you capture individual frames out of a video camera or off a video tape.
Frame Rate The number of frames that are shown or sent each second. Live action relates to a frame rate of 30 frames per second.
Fringing A white fringe appearing on the edges of objects in the image.

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GIF A graphic file format limited to 256 colors, which used mainly for web graphics or small animated files.
Gradation A smooth transition between black and white, one color and another, or color and no color.
Gray Level The brightness of a pixel.
Gray Scale An image containing shades of gray as well as black and white.

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Hot Shoe A flash connector generally found on the top of the camera that lets you attach a flash unit and trigger it in sync with the shutter.
Hunting An autofocus system that has trouble finding the focus in an image so that the system moves in and out of focus continuously, "hunting" for the correct focus point.

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IEEE-1284 A high-speed bidirectional parallel port specification used by printers and devices like card readers.
IEEE 1394 A port capable of transferring large amounts of data. Currently the fastest available port. Commonly known as Firewire.
IFF (Interchange File Format) the Amiga file format.
Image Formats The method of compressing and saving an image file.
Image Processing Time The time lag that occurs between the shutter is pressed and the camera is ready to take another picture, which occurs while the camera converts the image from an analog format to a digital format and stores the data.
Image Sensor A solid-state device containing a photosite for each pixel in the image. Each photosite records the brightness of the light that strikes it during an exposure.
Image Stabilization An optical or digital system for removing or reducing camera movement.
Inkjet A type of printer that sprays dots of ink onto paper to create the image. Modern inkjet printers can have resolutions of up to 2880 dpi (dots per inch) and create true photo-quality prints.
Interlaced An image sensor that gathers its data by first processing the odd lines and then the even lines. See also Progressive Scan.
Interpolation Method used to increase the resolution of an image map by adding pixels to an image based on the value of surrounding pixels. This method can cause artifacting.
IR (InfraRed) A method of transferring data from camera to a computer using a beam of invisible light, requiring no cables.
IrDA A standard that allows data to be transferred between devices using infrared light instead of cables.
ISO A number rating indicating the relative sensitivity to light of an image sensor or photographic film. Faster film (higher ISO) is more sensitive to light and requires less exposure than slower film.
Iris Diaphragm A continuously adjustable lens aperture consisting of interposed metal leaves.

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Jaggies Slang term for the stair-stepped appearance of a curved or angled line in digital imaging. The smaller the pixels, and the greater their number the less apparent the "jaggies". Also known as pixelization.
JFIF A specific type of the JPG file format. Also known as EXIF.
JPEG, JPG (Joint Photographic Experts Group) A lossy compression format, this is the most common type of image file format used in digital cameras.

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KB (Kilobyte) 1024 bytes.

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Landscape An image taken with the camera in its normal horizontal orientation.
LCD (Liquid Crystal Display) Two types: (1) a high-resolution color display device used in handheld televisions and digital photography viewfinders. (2) A monochrome information display using black alphanumeric characters on a gray/green background.
Lossless An image format which stores the image in a non-compressed format.
Lossy An image format that sacrifices a certain amount of image information in order to create a smaller compressed file.
LZW (Lempel-Ziv-Welch) A compression scheme used to reduce the size of image files.

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Macro The ability of a lens to focus very close (less than 8") for taking pictures of small objects at a 1:1 ratio.
Matrix Array CCD's that can capture full-color images instantaneously.
Matrix Metering A metering method which uses the entire image; however, it breaks the area down into smaller segments and uses the individual readings to calculate the best possible exposure. Matrix-metering is the most accurate of the metering systems.
MiniDisc (MD) Digital recording media like a small floppy disc.
MB (Megabyte) 1024 kilobytes.
Megapixel (MP) Having a resolution of one million pixels. A megapixel digital camera has an image resolution of 1280 x 960 pixels or greater. The most common digital cameras are rated at 1.3 megapixel, 2.11 megapixel and 3.34 megapixel.
Memory Stick A flash memory storage device developed by Sony that comes in sizes from 4 MB up to 128 MB.
Metering The process of calculating the exposure from the existing light conditions. See: Matrix Metering, Spot Metering and Center Weighted
MMC (MultiMedia Card) A flash memory card used in some digital cameras and MP3 players.
Moiré A visible pattern that occurs when one or more halftone screens are misregistered in a color image.
MOV Apple QuickTime MOVie motion video file format.
MPEG (Motion Pictures Expert Group) A motion JPEG movie file.
Multi-megapixel An image or image sensor with over two million pixels.
Multi Spot Focusing An autofocus system using several different portions of the image to determine the proper focus.
Multiple Exposure An image made up of two or more superimposed images.

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Noise Misinterpreted pixels found in your digital image, usually occurring in longer exposures. Can be seen as misplaced or random bright pixels in the picture.

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Optical Zoom Indicates that the camera has a real multi-focal length lens, as opposed to a digital zoom, which magnifies the center portion of the picture.
Orientation Sensor A sensor that knows when you turn the camera to take a vertical shot and rotates the picture so it won't be displayed on it's side when you view it.
Overexposure An image that appears too light because of too much light reaching the sensor.

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Palette A thumbnail of all available colors to a computer or devices. The palette allows the user to chose which colors are available for the computer to display. The greater the number of colors, the larger the data file becomes and more processing time is required to display your images. If the system uses 24-bit color, then over 16.7 million colors are included in the palette.
Panorama A panorama shot is an extremely wide-view image created by capturing a series of images.
Parallel Port A port on the computer that is faster than a serial port but slower than SCSI, USB, or IEEE 1394 ports.
PC Card
PCMCIA Card
(Personal Computer Memory Card International Association) A credit card-sized device which can be a flash memory card, a network card, a modem or even a hard drive.
PCMCIA Adapter A device that allows the use of memory cards in a PCMCIA slot. The adapter accepts the smaller memory card and transfers its connections to a standard PCMCIA connection
PCX A compressed, lossy file format which supports RGB, indexed-color, grayscale, and bitmap color modes.
Photosite A small area on the surface of an image sensor that captures the brightness for a single pixel in the image. There is one photosite for every pixel in the image.
PICT A graphics file format used primarily on Macintosh® computers.
Pincushioning An effect which occurs with telephoto zoom, in which straight lines at the edges curve in toward the far corners.
Pixel (Picture Element) An individual element of either a CCD sensor or a digital image.
Pixelization An effect seen when you enlarge a digital image too much and the pixels become obvious. See also Jaggies.
PNG (Portable Network Graphics) A compressed image file format similar to JPG.
Point and Shoot A simple, easy to use camera with a minimum of user controls and automatic control of most functions.
Port A connection point on the computer that accepts a cable, allowing communication between the computer and another device.
Portrait mode Turning the camera to take a vertically oriented photograph.
PPI (Pixels Per Inch) A measurement to describe the size of a printed image. The higher the number, the more detailed the print will be.
Preview Screen A small LCD display screen on the back of the camera used to compose or look at photographs. Also called Electronic Viewfinder.
Progressive Scan An image sensor that gathers its data and processes each scan line one after another in sequence. Compare to Interlaced.

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QuickTime® A motion video standard created by Apple®. QuickTime® video sequences are stored as .MOV files and can contain an audio track. Additional information is available on the QuickTime website.
QVGA An image resolution of 320 x 240 pixels.

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RAM (Random Access Memory) The most common type of computer memory, which is used by the CPU to store software, programs, and data currently being used. RAM is usually volatile memory, meaning that when the computer is turned off, crashes, or loses power, the contents of the memory are lost. A large amount of RAM usually offers faster manipulation or faster background processing.
Rangefinder The viewfinder on most cameras is a separate viewing device that is independent of the lens. Often mounted above and to the right or left of the lens. It exhibits a problem known as parallax when trying to frame subjects closer than five feet from the camera so it is advisable to use the color LCD when shooting close-ups for this very reason.
RAW (CCD raw format) The uninterpolated data collected directly from the image sensor before processing.
Recycle time The time it takes to process and store a captured image.
Red-eye and Red-eye Reduction Red-eye is an effect caused by an electronic flash reflecting off of the human eye and making it look red. Red-eye reduction mode fires a preliminary flash to close the iris of the eye before firing the main flash to take the picture.
Refresh rate The time it takes the camera to capture the image after you press the shutter release.
Resolution Resolution is expressed as either the number of pixels counted horizontally by the number of pixels counted vertically or by the number of megapixels. It can be expressed as one of the following formats: QVGA (320 x 240), VGA (640 x 480), SVGA (800 x 600), XGA (1024 x 768) UXGA (1600 x 1200).
Resolution, Digital See Resolution, Interpolated.
Resolution, Interpolated A number based on adding pixels to the image. Note: interpolation does not add any new information to the image.
Resolution, Optical An absolute number that the camera's image sensor can physically record.
RGB (Red, Green and Blue) The color system used in most digital cameras in which the image is separated by capturing the red, green, and blue light separately and then are re-combined to create a full color image.

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Saturation The degree to which a color is undiluted by white light. If a color is 100 percent saturated, it contains no white light. If a color has no saturation, it is a shade of gray.
Scanner A device that uses light to read printed information and converts it into the computer in a digital form for editing.
SCSI (Small Computer System Interface) A high-speed input/output bus which is faster than serial and parallel ports but slower (and harder to configure) than USB and Firewire ports.
SD Card (Secure Digital card) A flash memory card identical in size and shape to the MultiMedia Card (MMC) flash cards.
Sensor An electronic device that converts the light allowed in by the shutter to an electrical signal.
Sepia Describing the shades of brown found in the pictures from very early in photography, the term is also used as a special effect on some digital cameras, which converts the existing image into shades of brown.
Serial Port Standard, but extremely slow, connection port found on most computers. Also called RS-232.
Shutter The device in the camera that opens and closes to let light from the scene strike the image sensor and expose the image. The three primary types used in digital photography are digital shutters, iris shutters and focal plane shutters.
Shutter Lag The time between pressing the shutter and actually capturing the image. This is due to the camera having to calculate the exposure, set the white balance and focus the lens.
Shutter Speed The length of time the shutter opens to let light pass through the lens to the focal plane
SLR (Single-lens Reflex) A camera that has one lens that is used for both composing the frame and capturing the image to memory, as opposed to Range Finder. The same as TTL.
SmartMedia (SSFDC, Solid State Floppy Disc Card) A popular form of flash memory card.
Smoothing An editing tool which averages pixels with their neighbors to reduces contrast and simulate an out-of-focus image.
Spot Metering A method of autoexposure based on a meter reading of a small circle in the center of the viewfinder.
SVGA An image resolution of 800 x 600 pixels.

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TIFF (Tagged Image File Format) An lossless uncompressed image file format that produces no artifacts as is common with other image formats such as JPG.
Telephoto A lens with a focal length that gives you the narrowest angle of coverage, good for bringing distant objects closer.
TFT (Thin Film Transistor) The type of hi-resolution color LCD screen used in many digital photography cameras.
Thermal Dye Sublimation see Dye Sub.
Thermo Autochrome Printer A printer technology that uses specialized paper with three heat-sensitive pigment layers (cyan, magenta, and yellow) in the paper. Each layer is sensitive to a different temperature. The printer selectively heats areas of the paper with ultraviolet light, one color at a time, to activate and then fix the pigments.
Thumbnail A small, low-resolution version of a larger image file that is used for quick identification.
Time-Lapse Capturing a series of images at preset intervals.
True Color Color with a depth of 24-bits and 16.7 million colors.
TTL (Through The Lens) An autofocus or autoexposure system that works through the camera's lens.
Type I, II, III Denotes various PCMCIA or PC Card storage devices (both flash memory and removable hard disk drives). Type I and II fit in the single-height card slots, Type III only fit in the double-height slots.
TWAIN A protocol for exchanging information between applications and devices such as scanners and digital cameras. TWAIN makes it possible for digital cameras and software to "talk" with one another on PCs.

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Underexposure A picture that appears too dark because not enough light got to the imaging system.
Unsharp Masking A process by which the apparent detail of an image is increased; generally accomplished by the input scanner or through computer manipulation.
Upload Send a file from your computer to another device.
URL (Uniform Resource Locator) The address of a Web site.
USB (Universal Serial Bus) A high-speed port found on digital photography devices and newer computers, which allows much faster transfer speeds than a serial or parallel port.
UXGA An image resolution of 1600 x 1200 pixels.

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VGA An image resolution of 640 x 480 pixels.
Video Card A card the fits into a computer's expansion slot so you can edit digital video.
Video Out An output jack which can connect to televisions, monitors, and VCR's using either NTSC or PAL format.
Viewfinder The window you use to frame the subject.
Viewfinder, Optical An eyelevel viewfinder that is used to compose the photograph.
Viewfinder, Electronic A small color LCD with a magnified lens that displays the scene being presented to the image sensor.

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Wide-angle Lens A lens using the focal length that gives you the widest angle of coverage, also called a short-focal-length lens.

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XGA An image resolution of 1024 x 768 pixels.

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ZLR (Zoom Lens Reflex) A term used by Olympus® to describe their fixed mount lens SLR type cameras. An SLR camera has interchangeable lenses, a ZLR has a non-removable lens.
Zoom Lens A variable focal length lens. The most common zoom lens on digital cameras has a 3:1 ratio.

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