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The Heidelberg website glossary explains, in alphabetical order, a multitude of terms relevant to printing, as well as some terms used in Heidelberg's product catalogue.

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Rag

Fiber from cotton material.

Rag paper

Paper with a rag content of at least 10 percent primarily used for banknotes and documents.

RAL colors

Standard colors based on a series of color collections for industry published by the Deutsches Institut für Gütesicherung und Kennzeichnung, Sankt Augustin. There are over 2,000 RAL colors, and the RAL Design System, a color system which takes in the entire color space, contains 1688 color tones. All RAL colors in the RAL Design System and the RAL 840-HR classical color collection are also defined digitally. They can be used with all standard graphic arts programs and can be used with more than 20 output variants, that is with different screens and printers.

RAM (random access memory)

The memory a computer utilizes when in operation and that is lost when the machine is switched off.

RAMDAC (random access memory digital-to-analog converter)

A direct access storage or memory used to convert digitally encoded data into analog signals performed by specific chips.

Rasterizer

A software program that converts font data for output as raster graphics, that is, into bitmaps. This step must be performed before characters can be displayed on the monitor or printed as a hardcopy. Unlike vector graphics, a raster graphic consists of pixels arranged in a fixed grid.

Raw text

Raw text is a type of text design in which the lines are not made to be of uniform length by correspondingly enlarging the spaces between words. Deliberately varying line lengths as a creative technique is referred to as ragged setting.

Ream

A unit of measurement for sheets of paper. Though formerly defined as a 480 sheets, in the U.S. the term now refers to 500 sheets or, in the case of a so-called printer’s ream, 516 sheets. The German “new” ream refers to 1,000 sheets of paper.

Recycled paper

Paper produced from 100 percent used paper. Used paper fibers (also known as secondary fibers) can be used three to five times in this manner. If the recycled paper needs to be pure white, de-inking chemicals have to be used to remove the inks from the used paper, and the fibers also have to undergo a bleaching process.

Redigitization

Process by which print originals in the form of film material are converted back into digital data using scanners and software. The data can be stored in common file formats and then undergo further processing with the appropriate applications, thus allowing a print shop or prepress company to use the scanned films in a digital workflow.

Reduction factor

See "reproduction scale".

Reel spool

The take-up roll around which the paper web is wound after reaching the end of its journey through the paper machine.

Rendering

The accurate representation of three-dimensional models by a computer, whereby the object is given the most realistic surface possible, illuminated by an artificial light source and embedded in an equally three-dimensional environment with light, shadows, reflections, etc.

Reproduction scale (enlargement factor, reduction factor, reproduction ratio)

Ratio of the size of the reproduction to the original size of the object.

Resolution

In an optical context, a measure of the ability of input and output devices or of photographic films to visualize two adjacent dots independent of one another. The resolution depends on the physical properties of the visualizing or recording device or material and is usually limited by the wavelength of the light source. Resolution is usually given in dots per inch (dpi) or in lines per millimeter.

RFID (Radio Frequency Identification)

Labels used to identify objects that work with radio signals for data transmission in the production, transportation and storage sectors. Instead of barcodes and optical scanning devices, RFID systems use transponders as markers on the objects to be monitored. These units receive radio signals from the relevant interrogation devices and transmit their information back. Some of the key advantages of this technology include the fact that larger volumes of data can be stored in the transponders, the link between the transponder and the interrogation device is reliable without a direct line of sight, the data is interrogated more quickly and the data can be changed.

RGB

The standard additive color model for the primary colors red, green and blue, is used for self-illuminating output devices such as monitors, but also for electronic recording equipment such as scanners and video cameras.

RIP (raster image processor)

A processor that prepares data from the prepress stage for the production of printing plates. Its most important function is to create screens for printing images and other graphic elements. As a rule, an RIP is a separate computer, but it can also come in the form of software.

Rollover

A graphic or image that changes when the cursor is moved over it.

Roman face

The term used for fonts whose letters have small end-strokes (serifs) at the ends. The basic form of Roman face stems directly from the antique Capitalis style of the Romans. The upper-case letters are borrowed from the Roman script, while the lower-case letters come from the Caroline minuscule. Varying weights are another common feature of Roman faces. They are especially easy to read in running texts, and include Times, Bodoni and Garamond.

RTF (Rich Text Format)

A data format for texts that contains information on font, font size and formatting. The Rich Text Format was specified by Microsoft as a software-independent format for formatted texts.

Rub-off

The phenomenon by which pressure on stacked sheets causes ink on one surface to be smeared on to the next. This “carbon-copy effect” can occur due to the pressure of the clamp in trimming machines.

Rubber blanket

The blanket wrapped around the cylinder that is essential to the offset printing process. It transfers the printed image from the forme onto the paper. The term “offset” is derived from the process by which color is displaced onto the rubber blanket. Printing over a blanket provides an even print surface which makes it possible to work with coarse and granular papers.

Rubel, Ira Washington

Considered the inventor of the offset printing process. The owner of a small print shop in New Jersey, in 1903 Rubel accidentally discovered that he could obtain better results with indirect printing using a blanket cylinder than with direct printing. He covered the impression cylinder of a printing press with a rubber blanket and paper sheets were then fed incorrectly several times during a printing run. The impression from the printing forme ended up on the rubber blanket and from there was passed on to the back of the sheet. Rubel discovered that these misprints were of a better quality than the regular prints, and consequently went on to develop the first offset printing press.

Running directions

The direction through which paper is passed through the paper machine, generally the same as the grain direction. The running direction is often indicated by an arrow on sheet packages. See also “grain direction”.

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