Maximum density. The greatest density in an image. Also, the greatest density possible for a particular film or paper.

Minimum density. The smallest density in a image. Also, the smallest density possible for a particular film or paper.

A graph of density (D) against the logarithm of exposure (log E) Used in sensitometry to compare the sensitivity of different emulsions to light.

link together sequentially as in linking multiple drives on the SCSI bus.

(Desktop Colour Separation) A format that contains five PostScript files for each colour image.

Straightening an image that as been scanned crookedly, or straightening type that is slanted.

To remove or reduce speckles or dust spots introduced during scanning or image processing.

The distance between two colours in the CIELAB colour space, used to indicate colour differences and to establish quantitative colour tolerances.

A hardware device to measure the amount of light transmitted through film to check the quality of imagesetter output. Also a software feature for measuring the grey and RGB levels of an on-screen image.

The relative amount of silver in various areas of film or paper after exposure or development therefore the darkness of a photographic print or the light-stopping ability of a negative or transparency.

"The zone of acceptable sharpness in a picture extending in front of and behind the plane of the subject, that is most precisely focused by the lens. You can control or exploit depth of field by varying three factors

Scale on a lens barrel showing the near and far limits of depth of field possible when the lens is set at any particular focus and aperture.

Depth of focus refers to the zone in front of and behind the focal plane in which the blurred image point is smaller than the acceptable circle of confusion. An image, if it is not on the focal plane but within the depth of focus, is distinguished as a sharp image although it is, in fact, slightly blurred. Depth of focus depends on the f-number and the acceptable circle of confusion. The focal length of the lens does not affect the depth of focus.

Removal of halftone dot patterns during or after scanning printed matter by defocusing the image. This avoid moiré patterning and colour shifts during subsequent halftone reprinting.

Software that tells the computer how to communicate with a peripheral device, i.e. printer, CD-ROM.

A representation, in the CIE model, of the colour rendering characteristics of any input, display or output device.

Describes a colour space that can be defined only by using information on the colour-rendering capabilities of a specific device.

Describes a colour space that can be defined using the full gamut of human vision, as defined by a standard observer, independent of the colour- rendering capabilities of any specific device.

Light that has lost some intensity by being reflected or by passing through a translucent material. Diffusion softens light, eliminating both glare and harsh shadows, and thus can be of great value in photography, notably in portraiture.

A material that softens light passing through it. The effect is to soften the character of light. The closer a diffuser is to a light source the less it scatters light.

A flat glass with a pattern of lines or concentric rings that breaks up and scatters light from an enlarger or camera lens and softens detail in a photograph.

"An enlarger that illuminates the negative by scattering light from many angles evenly over the surface of the negative. detail is not as sharp as with a condenser enlarger

"A system whereby information is represented by binary digits, or "bits." Binary information has two states, "0" and "1,"or "on" and "off," and can thus be easily processed by electronic systems. Analog information can be converted to and from digital information via devices called "Analog to Digital Converters" or "Digital to Analog Converters." Digital information does not suffer from the degradation and noise problems prevalent in analog circuits."

"Instead of using film, this kind of camera records data in "pixels," small squares of light of varying hues that can be directly loaded into and interpreted by a computer."

Reproductions of an image that are produced by scanning the original analog image to produce a digital image file, and then imaging the digital file using some variety of digital printing or recording device.

"A digital "container" that surrounds an image with information (or metadata) in a file. Such information might be used to find the image, guarantee its authenticity, or limit access to authorized users. An envelope adds additional "overhead" to a file in excess of the actual "data" of an image."

The analogous component in digital cameras to film in optical cameras. This usually consists of some type of semiconductor memory, with or without additional components, usually in the physical form of a removable cartridge.

The use of fine pixels to create the halftone pattern that is then written to film, direct-to-plate or direct-to-press for printing.

Processing on an image performed by combining or comparing individual pixels with their neighbors. Many interesting and useful effects can be obtained, such as sharpening, blurring, edge detection, and embossing.

A method of image editing in which a picture is recorded as digital information that can be read and manipulated by a computer, and subsequently reformed as a visible image.

Internegs that are produced by digitally scanning the original transparency to create a digital file, and then imaging the digital data using a film recorder to record the image onto a negative film stock.

A printing device that is capable of translating digital data into hardcopy output.

Microprocessor chips specially designed to convert, modify and manipulate streams of digitized signals in real time. These chips allow for faster telephony, faxing, and audio and video capture and editing.

Rather different from Optical Zoom. With Digital Zoom the image is magnified by spacing out the pixels electronically, and as such is really very little different from blowing an image up to a larger size using a software package on your PC. Digital Zoom has a detrimental effect on image quality, so depending on your application, you need to be careful how you use it.

To convert an image into binary code. Visual images are digitized by scanning them and assigning a binary code to the resulting vector graphic or bit-mapped image data.

The reduction in the strength of a liquid by mixing it with an appropriate quantity of water.

A phenomenon in which straight lines are not rendered perfectly straight in a picture. There are two types of distortion--barrel distortion and pincushion distortion. Distortion cannot be improved by stopping down the lens.

A halftoning process that uses clusters of dots rather than evenly spaced halftone cells.

(Direct Memory Access) - Allows the I/O subsystem to access main memory for the transfer of data.

In photographic printing, to dodge a print is to reduce the exposure in a section of the image to make that area lighter. Compare this to the technique of burning.

"The smallest raster element of an image. Many dots together produce one pixel. Meaning, for example, that in the specification "8 bit depth", three "layers" of 256 dots each are on top of one another to produce one pixel."

A printing defect in which halftone dots print larger than intended.

The distance between the dots on a computer monitor, typically 0.2 to 0.3 millimeters. The closer the dots the sharper the image on the monitor.

Minute, symmetrical individual subdivisions of the printing surface formed by a half-tone screen.

Two pictures taken on one frame, or two images printed on one piece of photographic paper.

The process of moving computer data from one location to another. Though the term is normally used to describe the transfer, or downloading, of data from the Internet, it is also used to describe the transfer of photos from a camera memory card to the computer. Example: I downloaded photos to my PC.

(dots per inch) The unit of measure for a printerÕs output resolution. Also used for scanner resolution although ppi or spi is more accurate.

A colour that you set the scanner not to recognise.

The ability of a scanner to register a wide range of tonal values--something from near white to near black. A scanner with good dynamic range is able to map input shades correctly to output shades, making images look brighter and giving them more visible detail. Generally the number of bits determines the maximum dynamic range of a scanner. For example a 36-bit scanner has a higher dynamic range than a 24-bit scanner.