Xerox 721P87491 manual Rendering of color and gray values transfer function

Page 48

POSTSCRIPT

Rendering of color and gray values: transfer function

PostScript devices approximate source color values by a sampling and halftoning technique. These values can be modified by changing the output transfer function. The transfer function permits the correction of color (including gray) values to compensate for nonlinear color (and gray) level response in both an output device and the human eye.

The color levels presented to the setcmykcolor, sethsbcolor, setrgbcolor, and setgray operators and appearing as sampled data are not used directly, but are mapped through the current transfer functions. The resulting output consists of combinations of black and white on the DocuPrint monochrome printer, and black, white, and highlight color on the DocuPrint highlight color printers.

Note: The internal default transfer function in DocuPrint cannot be bypassed. Currently, there is an internal table that is used for converting input requests for a color value to a different number that is used to set the output device color level.

On the DocuPrint monochrome printer, PostScript masters that rely on the null transfer function (null transfer function is {} settransfer) do not overwrite the internal transfer function.

Furthermore, the operator currenttransfer returns what appears to be a null transfer function, that is, {}. However, the internal transfer function is not null. This achieves compatibility, because the xerography differs between DocuPrint and LaserWriter.

Note: For DocuPrint monochrome printers only, provision is made for compatibility with pattern generation, as long as the spot function returns values of 0 or 1.

When a gray value is presented to the setgray operator, DocuPrint

NPS performs the following processes:

1.Computes the index by multiplying the gray value by 255.0 and rounding the result:

index = Round (gray x 255.0 + 0.5)

2.Sets the device gray value to the value in the transfer array at the which the index was calculated:

device color = transferarray[index]

Note: Settransfer actually sets the transfer functions for all four color components (red, green, blue, and gray) to the same value. The setcolortransfer operator sets the transfer functions individually.

2-22

XEROX DOCUPRINT NPS GUIDE TO USING PAGE DESCRIPTION LANGUAGES

Page 47 Page 49
Image 48
Page 47 Page 49
Contents Version 7.1 August 2000 721P87491 Page Laser safety Operation safetyOzone information Conductor may result in risk of electrical shock. grounding Table of contents PostScript Vipp IndexViii Contents About this guideConventions Introduction Related publications Related informationPostScript publications HP PCL 5 publications Vipp publicationPCL Maintaining image qualityOFF PCL 5 media support PCL 5 font supportPCL 5 fonts installed with NPS software PCL command support PJL commandsPCL Copy command PCL Copy command example Duplex PCL Copy command examplePCL Duplex commands PCL Duplex commands DocuPrint NPS Collated HP LaserJet 4siPCL Job Separation command PCL Paper Source command tray assignment PCL media selectionPrecedence in selecting media PCL Output Bin command PCL Offset Registration commandsPCL 5c support PCL 5 coding recommendationsPCL 5c coding recommendations PCL 5c functions not applicable to DocuPrint NPSDriver recommendations for PCL 5c Limitations for custom PCL 5c driversCoordinate system default matrix Implementation-dependent operationsFloating-point arithmetic and math operators Fonts Adobe Type1 PostScript fontsFont Typeface Loading fonts User-defined fontsUsing Adobe Type 1 fonts Type 1 fontsUsing a Type 1 font in a document Producing Type 1 fonts for use with DocuPrintPostScript with embedded PJL commands PostScript language extensionsSystem Dict User Dict Server DictStatus Dict IdleTime DictionaryDfltkIdleArry needflush Nonstandard definitions Printer resolution and resolution enhancement Appearance consistencyExamples of nonstandard definitions Statusdict UserdictDpi image Printed on a 300 dpi printer Printer imaging characteristics Font consistency Proprietary PostScript extensionsControl-Z and superfluous errors Control-D as binary data and end-of-jobSolution to control-Z and control-D problems Multiple jobs in one input file DocuPrint NPS implementation of PostScript Level Simulated mixed plexPrinter Controller operations Scan conversion detailsStroke Fill ShapesZero-width lines strokes Curved shapesImages Image quality Rendering of color and gray values transfer function PostScript printer description PPD files Implementation limitsFile operators and standard devices Implementation limitsQuantity Limit Description Path limits PostScript VM limitsSetCacheDevice Device orientation and setscreen operatorPostScript storage object size limits Obsolete operators-banddevice, framedevice, renderbandsArc to Bezier conversion-pathforall Creating the necessary PostScript Ccitt Group 3 Print performance related to image printingScan order and rotation Purpose Image orientation mismatch aImage orientation mismatch B 10.Image pixel sequence example Considerations SummaryScan resolution and scaling 11.Scaling and resolution example12.PostScript with embedded image normal scan order MaxX exch def /minY exch def /minX exch def 14.Actual PostScript print Page Vipp Functionality Operating environmentVipp line mode extension XGFNub Page Symbols CcittIndex PCL PPD Index

721P87491 specifications

The Xerox 721P87491 is a remarkable printing device that showcases advanced technology tailored for professional environments, ensuring high-quality output and efficiency. Aimed at meeting the demands of busy offices, this model is recognized for its reliability and innovative features.

At the core of the Xerox 721P87491's appeal is its robust printing capabilities. It offers an impressive resolution, enabling the production of crisp and clear documents, whether in black and white or color. This high-resolution output is particularly essential for businesses that require detailed graphics, intricate charts, or professional-grade presentations.

One of the standout features of the Xerox 721P87491 is its impressive speed. It is designed to handle high-volume printing, significantly enhancing productivity in fast-paced work environments. With a rapid print speed per minute, users can expect swift processing of print jobs, ensuring that document delivery times are minimized.

The device also boasts advanced connectivity options. It supports both wired and wireless connections, allowing for seamless integration into a variety of office networks. This flexibility facilitates printing from multiple devices, including desktop computers, laptops, and mobile devices, enhancing overall workflow and collaboration within teams.

Additionally, the Xerox 721P87491 incorporates user-friendly interface options. With an intuitive touchscreen display, navigating the printer's functions becomes simpler. Users can easily access common features, adjust settings, and manage print jobs efficiently.

Another notable characteristic is its advanced security features. Given today's emphasis on data protection, the Xerox 721P87491 is equipped with robust security protocols to safeguard sensitive documents. It includes features like secure print, which holds documents until the authorized user enters a PIN, ensuring confidentiality in high-stakes environments.

Moreover, the Xerox 721P87491 demonstrates an emphasis on environmental sustainability. It is designed to be energy efficient, reducing power consumption during both idle and active states. The printer also supports duplex printing, which helps decrease paper use, contributing to a more sustainable office practice.

In summary, the Xerox 721P87491 is a versatile printing solution that merges efficiency, quality, and advanced technology. With high-speed printing, intuitive controls, robust security features, and a commitment to sustainability, it stands out as an excellent choice for businesses aiming to boost productivity while maintaining high standards. Its capabilities make it a worthy investment for any modern office environment.
Top Page Image Contents