Lecture 10: Print Reproduction Screening

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Questions and Answers

What is the purpose of halftone patterns in process colors?

To create spot colors

To apply ink or toner in a stochastic pattern

To create a rosette pattern

To represent tints of each base color (correct)

How are tints created in spot colors?

Through process colors

Through offset lithography

Through screening (correct)

Through halftone patterns

What is an advantage of using spot colors?

They are used for stochastic screening

They are used for process colors

They are used for high-volume print production

They provide exact color matches (correct)

What method dominates high-volume print production?

Offset lithography Signup and view all the answers

What is the purpose of the pre-press phase in offset lithography?

To produce printing plates Signup and view all the answers

What is a printing plate in offset lithography?

A sheet of aluminum that receives a positive, latent image Signup and view all the answers

What is the purpose of a proof in offset lithography?

To ensure that the map will be reproduced as intended Signup and view all the answers

What is the purpose of the offset press in offset lithography?

To transfer the image onto the print medium Signup and view all the answers

How do multicolor print jobs work in offset lithography?

One printing unit for each base color Signup and view all the answers

What is the characteristic of offset lithography that allows for a significant decrease in cost per unit as the number of copies increases?

Economies of scale Signup and view all the answers

What is the sequential order of colors in the ribbon?

Cyan, magenta, yellow, and black Signup and view all the answers

What is the highest quality graphic output obtained from?

Imagesetters Signup and view all the answers

What type of plotters are commonly used in proofing or producing a few copies of a large-format map in color?

Vector plotters Signup and view all the answers

What is the effect of stepping in vector plotters?

Zigzag increments along diagonal lines Signup and view all the answers

What is the problem that arises when maps designed and constructed in one medium are reproduced in another medium?

Mixed-media degradation Signup and view all the answers

What is the primary use of desktop thermal printers in cartographic production units?

Color proofing of small-size maps Signup and view all the answers

What is the characteristic of imagesetters that makes them suitable for high-volume print production?

They are relatively expensive and found in large mapping establishments Signup and view all the answers

What is the format in which some imagesetters work?

Large format at map reproduction scale Signup and view all the answers

What is a characteristic of electrostatic plotters?

They use one or more linear arrays of printing nibs to build up an image. Signup and view all the answers

What is the resolution limit of ink-jet printers?

300 dpi or less Signup and view all the answers

What is a characteristic of laser printers?

They are slower and more expensive than electrostatic and ink-jet printers. Signup and view all the answers

What is the difference between laser printer output at 300 dpi and 600 dpi?

The 300 dpi output is visibly inferior in graphic quality compared with the 600 dpi output. Signup and view all the answers

What is used in thermal printers?

A page-sized inking ribbon Signup and view all the answers

What is the coating on the ribbon in thermal printers?

Wax or plastic impregnated with color pigments Signup and view all the answers

What is the process referred to in laser printers?

Xerography Signup and view all the answers

What is the use of desktop laser printers in cartographic production units?

Convenient proofing devices Signup and view all the answers

Study Notes

Screening for Print Reproduction

Stochastic Screening is used primarily with ink-jet printing, applying ink or toner in a pattern of very small, pseudo-randomly spaced dots of uniform size.
Frequency Modulation (F.M.) is used in screening.

Aspects of Color Printing

Process Colors: CMYK (subtractive primaries + black) are mixed on the page by applying them in sequence to the same area.
When mixed, tints of each base color are represented by halftone patterns, each with a unique screen angle.
Spot Colors: opaque inks that are premixed before reaching the printing device, allowing for exact color matches.
Tints can be created through screening.

High Volume Print Production

Large numbers of maps require high-volume reproduction methods.
Offset Lithography is the dominant method for high-volume reproduction.
Other methods like laser and ink-jet printing become too costly or time-consuming.

Offset Lithography

A printing process where ink sticks only to certain areas of a surface.
Virtually all mass-produced maps are the result of offset lithography.
Characterized by excellent print quality and high printing speed.
Provides a significant decrease in the cost per unit as the number of copies increases.
Performed on an offset lithographic printing press.

Pre-press Phase

Consists of various technologies and procedures that make offset lithographic printing possible.
Printing plates are produced, and proofs are created.

Printing Plate

A sheet of aluminum that is ultimately mounted on a roller on an offset press.
Receives a positive, latent (invisible) image that ink will stick to.
One is created for each color.
Mounted on an offset press, washed with ink, and used to transfer an image onto the print medium.

Proof

A representation of what the final, reproduced map will look like.
An essential component of the pre-press phase.
Used in conjunction with editing to ensure that the map will be reproduced as intended.
Various levels of quality/cost.

File Formats for Pre-press

Digital maps can be delivered to the service bureau in various formats.
In the native format of the application software that created it (.MXD, .AI).
In a page description language (PostScript).
In a portable document format (EPS, PDF).

Offset Lithographic Printing

The offset press has one or more printing units that transfer ink to the print medium.
Each printing unit is capable of printing one base color.
The image is transferred from the printing plate to the blanket cylinder, which then transfers the image onto the print medium.
Multicolor print jobs employ multiple printing units, one for each base color.

Map Production

Diagram of the digital map production system currently used in the University of Wisconsin Cartographic Laboratory.

Output Options

Ink-Jet Printers: spray-print the artwork onto the image medium (uncoated paper or clear film).
Laser Printers: work much like a standard xerographic copier, using electronic xerography.
Thermal Printers: use a page-sized inking ribbon, a coated receptor material, and a heat-producing printhead.
Imagesetters: obtain high-quality graphic output by plotting in raster fashion directly on photographic film or paper.
Vector Plotters: plot mechanically, used for proofing or producing a few copies of a large-format map in color.

Digital Production Problems

Mixed-Media Degradation: when maps designed and constructed in one medium are reproduced in another medium, fidelity problems are common.

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Description

This lecture covers stochastic screening, a technique used in ink-jet printing, and frequency modulation. It explores the aspects of color printing and print reproduction.