Output

Densitometer
A device used to measure light absorbed by a piece of film or a substrate. A transmission densitometer is used for film and will read out density and halftone dot percentage. These devices are used to calibrate an output device. A device called a reflective densitometer is used to measure reflective surfaces such as a proof or a press sheet.
Density Adjustment
The first step in calibrating an output device. Density adjustment is accomplished by adjusting laser exposure and film development characteristics. Results are measured with a transmission densitometer which is used to measure the density of the film coming from the output device and developed in the processor.
Emulsion Up/Emulsion Down
Emulsion is the chemical coating on film that holds the image. This term describes the orientation of the emulsion when looking at the film and reading the type on it. Depending upon other prepress steps, it will be appropriate to create film that reads correctly (versus mirror image reversal) when the emulsion is up or when it is down. Sometimes abbreviated RREU or RRED standing for "right reading emulsion up (or down.)
Film
Material that is loaded into an imagesetter. Film is coated with a light sensitive emulsion and exposed with laser light inside the output device. After chemical development the film holds a very sharp image of the layout created by the designer. This film is used to prepare printing plates for a press run.
Hardcopy
Hardcopy is the generic term used to describe the materials containing images of our layouts and artwork that come out of a laser printer or an imagesetter.
Imagesetter
An output device containing a laser that is used to form an image on film from desktop files. Particularly, an output device equipped with a PostScript RIP to interpret commands in the PostScript language.
Laser Printer
(Some, but not all Laser Printers have PostScript capabilities.) A hardware device found in most offices that uses laser technology to form an image that is transferred to paper. It is toner particles (like a copier) that actually mark the page. Laser printers have an attribute of Resolution that is expressed as DPI (dots per inch.) 600 DPI lasers are most common but there are specialized lasers with greater resolution.
Linearization
A term referring to part of the calibration process for an imagesetter. Linearizing is the process by which one makes sure that a requested 40% halftone dot will output and measure as a 40% halftone dot. An output device is typically linearized by outputting a test file containing small patches of grey in 5% steps from 0% to 100%. Each patch on the resulting film is measured with a transmission densitometer and recorded in the calibration software. The resulting settings become a filter through all future files are output.
On-line Processor
For the development of film coming from an imagesetter, an on-line processor is connected directly to the imagesetter and exposed film is automatically carried from the imagesetter into the various chemical baths required for processing the film. It is generally considered preferable to have an on-line processor because it eliminates the need for the operator to hand carry exposed film to a remote processor.
Output Device
A printer. The term is most often used to describe a high-resolution imagesetter that is used to output desktop page layouts to film negatives.
Paper
A term used for the material that is fed through a laser printer. Also refers to the photographic material that can be used in an imagesetter as an alternate to film.
Plotter
An alternate term for an imagesetter. See imagesetter.
PostScript
A page description language described by its creator (Adobe Systems) as "the language of desktop publishing." The PostScript language is a programming language spoken by desktop software after the "print" command is issued. These PostScript instructions created by the software (in partnership with the printer driver) are sent to a PostScript laser printer to describe the page the user wishes to have output. The PostScript laser printer has an interpreter inside (called a RIP) that takes that page description and instructs the laser how to image the page.
PostScript Dump
The act of printing a page layout to a disk file rather than printing directly to a PostScript laser printer. This allows the user to transport the file to another location and download it to a PostScript laser printer. See PostScript.
PostScript Error
An event that occurs during the printing of a page layout. A PostScript error can occur when a page is too complex or it contains an element that has a technical defect. When a PostScript error occurs, the printing of that file terminates and usually no hardcopy emerges. To troubleshoot the problem, an individual knowledgeable in the PostScript language can (often) analyze the error and know where in the page layout to look for the troublesome element.
PostScript File
A file created by printing a page layout to a disk file rather than printing directly to a PostScript laser printer. This allows the user to transport the file to another location and download it to a PostScript laser printer. See PostScript.
Print Command
The command, present in all software that initiates the process of creating hardcopy. See also PostScript.
Print PostScript to Disk
The act of printing a page layout to a disk file rather than printing directly to a PostScript laser printer. This allows the user to transport the file to another location and download it to a PostScript laser printer. See PostScript.
Printer Driver
Important computer software that facilitates communication between software and the output device. See also PostScript.
Processor
For the development of film coming from an imagesetter, a processor contains the various chemical baths required for processing the film.
Resolution of an Output Device
Resolution of an Output Device is expressed as DPI (dots per inch) and refers to the number of laser spots per inch. It is generally considered that having output resolution of 600 DPI or above is important for attractive but achieving quality halftone reproduction relys on having much more resolution than that. A properly formed halftone dot will require a resolution many times higher than the halftone ruling. (A 150 line screen is best when output at a resolution of 2540 DPI.) This is why quality imagesetters have peak resolutions measured 3000 DPI and above.
RIP
Raster Image Processor. A RIP is a part of a PostScript laser printer and part of a PostScript imagesetter. It is a special computer that converts PostScript page descriptions into a rasterized image that can be edited or output directly. (A page layout must be ripped before it can be output.) See also PostScript
Ripping
The act of processing a PostScript file on a RIP. See also RIP
Service Bureau
An organization (frequently born out of an existing typesetting business) equipped with PostScript imagesetters and providing simple output services. Typically solicit business with low prices and quick turn-around times.
Spooler
A term referring to a specific productivity boosting software utility. A print spooler manages the print out function for the user and allows the user to regain control of their computer much faster than without. Also, a spooler will often coordinate print jobs received from many users sharing a particular laser printer; storing each print job in a "print queue" and sending them to the laser one at a time.
Spot Size
A term referring to the smallest element an imagesetter marks onto the page. Measured in microns, these spots are the building blocks that are used to create letter forms and halftone dots. When one refers to the resolution of an imagesetter (expressed in DPI) one is referring to the matrix in which these spots are imaged, not particularly to the size of the spot itself. Modern imagesetters have several spot sizes available for specialized purposes such as stochastic screening.
Stochastic Screening
Stochastic screening is a halftoning technology available in certain Output Devices where very small dots are positioned with varying spacing. Putting dots closer together simulates darker areas and putting them farther apart simulates lighter areas. Considered much harder to output and proof, there are two benefits to the user: Greater detail in any photographic image printed with Stochastic film. Elimination of screen angles allowing process color printing with more than four inks. Each imagesetter manufacturer has their own trade name for their Stochastic Screening technology.