Acrobat
A file created in Adobe Acrobat 'Portable Document Format' or PDF. PDF files typically define object relative position, type style employed, colour, size of page and whether raster or vector graphic files. By defining each object in mathematical terms, as does the PostScript printing language, a file can be compressed in size with little apparent loss in quality. In a PDF file, the relative resolution can also be defined. It is also platform-independent - capable of use by Apple and Windows users alike. To create an Acrobat file, the application program (i.e. Adobe Photoshop CS, Adobe InDesign etc) must include a Distiller component, to save the source file into the Acrobat PDF format. As of September 2004, the current release was Acrobat 6.02
Adjustment Layers
Often you want to experiment with colours when retouching images. An adjustment layer can be set up in programs like Adobe Photoshop or Jasc PaintShop Pro to allow you to try such changes, store the interim adjustment, but come back to the original later if it didn't work out. Adjustment layers can also be used to change relative brightness and contrast of selected items.
Anti-Alias
Anti-aliasing smoothes the edges of objects and the transitions between them. It is used when displaying type on a computer monitor to smooth the otherwise rough edges of rounded objects when displayed in square picture element displays. Anti-aliasing is also used when laying one object cut from one background colour and superimposed over another. An anti-alias filter is also employed over CCD sensors in digital cameras to integrate the R, G and B pixels.
Artifacts:
Unwanted effects in the image such as blotches (from over-compression), Christmas tree lights (multi-colored speckles from bright highlights), noise (granularity from underexposure) and other aberrations that sometimes afflict digicam images.
Aspherical Lens:
A lens designed to reproduce images better by having its edges flattened so that it is not a perfect sphere, hence: "a" (not) "spherical" (a sphere).
Autofocus: The camera automatically focuses on a subject or object at which it is pointed.
Bit:
The smallest unit of memory; a contraction from ´binary´ and ´digit´. Binary digits are 0 and 1, also known as ons and offs.
Bit Depth:
This refers to 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.) CCD are colored in a pixel by pixel method.
30/32 bit color is billions of colors. (Only supported with high-end CPU´s.)
24 bit color resolution is 16.7 million colors.
16 bit color is 32,000 colors.
8 bit color is 256 color
8 bit gray scale is 256 shades of gray
4 bit 64 colors or gray
2 bit black or white.
Bitmap:
The method of storing information that maps an image pixel, bit by bit. There are many bitmapped file formats, .bmp, .pcx, .pict, .pict-2, tiff, .tif, .gif (89a), and so on. Most image files are bit mapped. This type of file gives you the ´jaggies´, when examined closely you can see the line of pixels that create edges. Bitmap images are used by all computers. The desktop or screen information for all Windows machines uses .bmp files, while the Macintosh uses pict files.
CCD:
Charge-coupled device. The sensor array that makes up the imaging surface of the digicam. The more sensors a CCD has, the higher the image resolution will be.
CMYK:
Cyan, Magenta, Yellow, Black; These are the printer colors used to create color prints. Most Color Printers, Ink-Jet, Laser, Dye-Sublimation, Thermal, and Crayon printers use these as their printer colors. (This is one of the color management problems for computers. Converting RGB files to CMYK files cause´s color shifts.) When used by a printer the CMYK is also known as a reflective color since it is printed on paper, or reflective films
Color Temperature:
A method of describing the qualities of warm (yellowish) or cool (bluish) light and measuring it in Degrees Kelvin (°K).
Compact Flash:
A matchbook-sized memory card used in many digital cameras today and presently capable of storing over 200MB of information.
Compact Flash II:
A new Compact Flash standard with increased capacity.
Compression:
Process of compacting digital data, images and text. Software algorithms search the raster image to build a greatly condensed (from a file storage perspective) format of the image. In the case of CCITT Group IV, the file size reduction is about 25:1. The actual compression factor is greatly dependent upon the quality of the scan and upon the density of the information.
dpi:
Dots-per-inch. Printers lay down multiple dots of ink when printing to reproduce each pixel of the image. The higher the dpi rating of the printer, the better it can define each pixel. Also a measurement of a scanner’s resolution, although a more precise term would be spi (samples-per-inch).
Depth Of Field:
The range of sharpness in front of and behind the subject or object focused on.
Digital Zoom:
An electronic enlargement of part of the image making it appear to be closer and bigger, simulating an optical zoom lens at a telephoto setting. The image is actually cropped, resulting in loss of surrounding pixels and decreased resolution. In some digicams, interpolation is used to offset this loss. (see Interpolation).
Dye Sublimation:
A type of printing process in which a dye ribbon is heated by the print head creating a gas that hardens onto special paper. This creates soft-edged spots of color that melt into each other and give the appearance of a continuous tone photograph.
File Format:
The specific organization of data within a file. There are multiple raster and vector file formats, including TIFF, IOCA, Tiled TIFF, IGES and DXF. Some file formats have been specified for file interchange to facilitate data storage.
Filter:
A specialized mini-application to extend or offer unique expansions of a software package. Usually through the use of plug-in architecture. This is a key component of many imaging software packages
Fixed Focus:
The camera’s focus is pre-set to a distance at which most subjects or objects will be in focus from near to far. Not as precise as autofocus.
GIF:
Graphic Interface Format designed by CompuServe for using images on line art. This is a 256 color or 8 bit image. A file format that is more appropriate for flat art or line art. The GIF format supports transparency whereas the JPEG format does not.
Inkjet:
A type of printing in which dots of ink are sprayed onto paper to create the image. Some inkjet printers can lay down 1440 dots of ink per inch, resulting in photo-quality prints (provided that the image has adequate resolution in pixels to begin with).
Interpolation:
The process of adding or subtracting pixels to an image (usually in an imaging program) to increase or reduce its size at a desired resolution. Also known as resampling or upsampling and downsampling. Interpolation changes the file size of the image. See also: "Resizing."
ISO Equivalency:
A measure of the digicam’s sensitivity to light using conventional film speeds as a yardstick. Most digicams have fixed ISO (International Standards Organization) equivalents but others can be set to sensitivities ranging from 80—640 to achieve adequate exposure under different lighting conditions.
Jaggies:
The stair-stepping effect that can be seen in curves and diagonal lines when a picture’s resolution is too low and individual pixels begin to show in the image. The smaller the pixels, and the greater their number the less apparent the "jaggies". Also known as pixelization.
JPEG:
Image compression in digital imaging. There are several versions of JPEG, some proprietary. JPEG, also known as JFIF takes areas of 8 x 8 pixels and compresses the information to its lowest common value. This is one of the reasons you can get as many images in to the digital cameras. The results in decompression of the files can cause "blockyness", the "jaggies", or "pixelization" in some digital images. The higher the compression ratio the more the pixelization or blockyness occurs. The greater the pixel count the less pixelization may occur.
Lab Color:
L*a*b* is a color model developed by the Centre Internationale d´Eclairage (CIE). These standards are internationally accepted standards for all colormetric measurements. The Lab model, like other CIE color models, defines color values mathematically, in a device independent manner. Lab color is consistent color regardless of the device producing the color.
LCD Monitor:
The Liquid Crystal Display color screen on most digicams, usually 1.8 to 2.5 inches measured diagonally and used to check images after they are shot. The LCD monitor can also be used to frame pictures before they are taken and is usually more accurate than the optical viewfinder, though not as convenient to use.
Lens Distortion:
An abnormal rendering of lines in an image; most commonly they may appear to be bending inward (pincushion distortion) or outward (barrel distortion). Correctable by using a plug-in in an imaging program.
Lithium-ion (LI-ion):
A long-lasting rechargeable battery used in some digicams.
Macro: The ability of a lens to focus just inches away from an object or subject so as to produce big close-ups, sometimes even larger-than-life size.
Manual Focus:
The digicam’s focus can be set by the user at any point from near to far or in steps such as 3 feet, 15 feet, Infinity. A useful override feature on some autofocus cameras which sometimes refuse to fire when they cannot focus accurately in very low light or on fast-moving subjects or objects.
Maximum Aperture:
A measure of how much light can pass through a lens when its diaphragm is opened fully. Lenses with maximum apertures of f-2 or f-2.8 are categorized as "fast" and can produce correct exposures under lower light than "slow" lenses with maximum apertures of f-3.5 or smaller.
Megabyte:
1024 Kilobytes, written MB used to refer to size of files or media such as hard drives. Refers to amount of information in a file, or how much information can be contained on a Hard Drive or Disk.
MegaPixel (also MP):
One million pixels. When the length times width of a digicam’s pixel array reaches one million, its resolution is then described in MegaPixels. 1,300,000 pixels equals 1.3 MegaPixels. The greater the pixel count of an image the higher the resolution of that image.
Memory Card Reader:
Allows rapid transfer of images recorded on digicam memory cards to a computer. The memory card —containing a folder of images— shows up as an external drive on the computer’s desktop and the entire folder can be copied over to the hard drive in seconds.
MemoryStick:
Sony’s proprietary memory card.
Noise:
The electronic equivalent of excessive grain in a film image. Usually found in images shot at high ISO settings.
Optical Viewfinder:
An optical glass device on the digicam which, when looked through, shows the intended image to be photographed. The best digicams have optical viewfinders in addition to LCD monitors because the LCD can "wash out" in bright sunlight, making it virtually impossible to see the image.
Optical Zoom:
A zoom lens which uses movement of lens elements to achieve various fields of view. Regardless of whether the zoom is set for taking pictures at wide-angle or telephoto settings, the resolution of the image remains the same.
Photo CD:
A CD-ROM holding about 100 images, each scanned from slides or negatives at five different resolutions. The photographer can then choose the best resolution to achieve the size of a desired photo.
Picture CD:
Similar to Photo CD but with only one medium resolution scan for each image.
Pixel:
From a contraction of the words Picture Element. The basic element of resolution. Digicam resolution is expressed in pixels (not pixels-per-inch).
Pixelation:
See "Jaggies."
Plug-in:
A small application that can be added (plugged-in) to a program to give it more functionality. For example, a distortion-removal plug-in.
ppi:
Pixels-per-inch. A measurement used to describe the size of the final printed image. An image that has a higher number of pixels-per-inch will show more detail than one which has fewer pixels-per-inch.
Pre-Flash:
Some digicams fire two flashes, the first adjusts the white balance (see below) and the second exposes the picture. This is different from a red-eye reduction mode in which multiple weak flashes are fired to close down the subject’s iris prior to the actual exposure.
Rasterization :
The process that automatically converts vector and text into raster. This process is done on-the-fly for plotting, or can be stored as a file in raster format.
Red-Eye:
A phenomenon which occurs when the flash is fired directly into the subject’s eyes in a dimly lit or dark environment. Blood vessels in the back of the eye reflect their color back through the iris of the eye which is usually opened wide in dim light. Most digicams have a flash mode to reduce or eliminate this condition.
Reflex Viewing:
The intended image is viewed directly by your eye through the taking lens giving you as close to what you see as you’re apt to find. Also called TTL (through the lens) and SLR (single lens reflex) viewing.
Resizing:
In which the size of the image is changed by squeezing pixels together (to make them smaller) or spreading them apart (to make them bigger) without adding or subtracting any. Thus, the image’s file size remains the same. See also: "Interpolation."
Resolution (Res):
A measure of how much information a digital camera can record, usually expressed in pixels or MegaPixels and arrived at by multiplying the length (in pixels) times the width (in pixels) of the CCD sensor array.
RGB: Red, Green, and Blue:
The primary colors of light which, when mixed in varying proportions can produce all colors. Digital cameras and monitors use RGB to record and display colors.
Shutter Priority:
A mode in which a desired shutter speed is manually selected and locked in; the camera then chooses an appropriate lens opening (f-stop) for proper exposure. Used primarily to prevent motion-blur in fast-moving subjects or objects.
Slow Synch: A flash mode in which the image is given some exposure before or after the flash is fired so as to bring out details in the background that would normally be underexposed or not recorded at all.
SmartMedia: Also known as SSFDC (Solid State Floppy Disk Card). A postage stamp-sized memory card used by some digicam manufacturers as an alternative to Compact Flash cards and presently capable of storing up to 64MB of digital image information.
TIFF: Tagged Image File Format. Most digicam images are recorded as TIFFs and then JPEG-compressed in the camera. Some digicams now offer an uncompressed TIFF option so an image can be retrieved in its original state, eliminating the possibility of compression artifacts.
USB:
Universal Serial Bus. A computer port to which peripherals can be connected and, when used by a USB-equipped digicam, allows rapid transfer of digital camera images to the computer.
Vector Graphics:
The use of geometrical primitives such as points, lines, curves, and polygons to represent images in computer graphics. The rendering of shapes in a mathematical way. It is used by contrast to the term raster graphics, which is the representation of images as a collection of pixels
White Balance:
In which the color temperature of the scene is measured prior to exposure and electronically adjusted so that white objects will not take on excessive color casts of red, blue or, if shot under most fluorescent lighting, green.
Zoom Lens Apertures:
Designated as two maximum apertures on the lens ring as: 1:2.8—4.0. The first number after the "1" (f-2.8) applies if the lens is in full wide angle position. The second (f-4), if it is at full telephoto. Similarly, minimum apertures will also vary by a full f-stop. If the zoom is set between wide and telephoto, the maximum aperture will fall in the middle, in this case, f-3.5.
