24-bit color:
Condition where 16.7 million possible colors are displayed on the screen at one time.
48-bit:
Usually referring to a color file with three 16 bit grayscale channels, each defining 65,536 levels of grayscale brightness.
8-bit color:
256 possible colors displayed on the screen at one time.
8-bit grayscale:
256 possible levels of gray displayed on the screen at one time.
Analog:
continuously variable electrical signals.
Archival:
Stable over time, should be coupled with life estimate.
Binary:
A numbering system based on ones and zeros.
Bit:
The basic binary signal: 1 or 0, on or off, black or white.
Bit depth:
Levels of gray that can be seen or recorded by digital devices; 8 bit (256 levels of gray) is the native Macintosh bit depth.
Bitmap:
Any computer image made up of pixels. Photoshop's term for the line art mode (1 bit, black or white).
Byte:
8 bits (2x2x2x2x2x2x2x2) or 256 levels of gray.
CCD (Charge - Coupled Device):
A light-sensitive device that produces varying amounts of analog electrical current when struck by light. Commonly known as a "sensor".
Channel:
A single plane of image information; three grayscale channels (red, green, blue) are needed to produce a color image.
Chromatic aberration:
The failure of the three primary colors of light to come into focus at the same point.
CMYK:
Initials that stand for cyan, magenta, yellow , and black - the opposites of the primary colors of light (red, green, blue) on the color wheel. Also known as "subtractive color". The colors of the inks used in the printing process.
Compression:
Reductions of the size of a digital file through code repetition modeling or specific image compression technology like JPEG.
Contrast:
The relative intensity of blacks and whites.
CPU: (Central processing Unit)
The primary chip found with in a computer.
Curves:
An editing interface similar to film contrast curves.
Density:
The opacity of the image or ink.
DPI (Dots Per Inch):
Referring to the number of ink dots on an inch of paper. Not to be confused with PPI (Pixels Per inch).
Digital:
Information represented as on or off conditions; absolute values for gray level in images.
DNG:
Adobe's digital negative format, which is a documented standard for writing and reading raw digital image data.
Dye-Sublimation (Dye-Sub):
A heat dye-transfer process printer that creates prints that appear almost continuous-tone.
EPS (Encapsulated Postscript):
A postscript page description language file format.
Extrapolation:
A formula for decreasing the ppi (and file size) of an image, reducing the number of pixels.
Four-color:
Refers to the process color printing using cyan, magenta, yellow and black inks to reproduce full color photographs.
Gamma:
The overall contrast of the image expressed numerically.
Grayscale:
A continuous tone black and white image (256 levels of cray) similar to a black and white photograph.
Halftone:
An image filtered through a screen of dots to imitate a continuous-tone photograph by rendering it with large and small dots of ink to from light and dark areas of an image.
Highlights:
The lightest portion of an image.
Histogram:
A graphic representation of the distribution of grays in a digital image, essentially a pixel brightness counter.
Interpolation:
A formula for increasing the ppi (and file size) of an image, creating more pixels by sampling current pixel data and calculation the value for new pixels.
ISO (International Standards Organization):
Refers to film or an image sensor's sensitivity to light as defined by the International Standards Organization.
JPEG (Joint Photographic Experts Group):
A compressed file format developed by a committee to set a standard for image data compression.
Opacity:
Degree of transparency.
Pixel:
A picture element, individual block of data that makes up a digital image.
PPI (Pixels Per Inch)
Referring to the linear measure of pixels in an image (resolution).
RAW:
The image data captured by a digital camera sensor prior to being processed by custom software.
RGB:
A muti-channel image consisting of three grayscale images separated through red, green, and blue filters during scanning or the camera capture process.
Resolution:
The amount of data present to represent images (pixel dimensions), generally expressed as ppi(in conjunction with size: 300ppi 8 x 10 inches).
Saturation:
The relative intensity of color.
Shadows:
The darkest areas of an image.
Sharpen:
To make an image appear to be more in focus, usually through edge-contrast enhancement.
TIFF (Tagged Image File Format):
A protocol for image data.