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Method and Apparatus for rendering Grayscales at a printing device using a calibrated threshold matrix via the Virtual Printer.

IP.com Disclosure Number: IPCOM000014890D
Original Publication Date: 2000-Apr-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 3 page(s) / 62K

Publishing Venue

IBM

Abstract

Described is a method for increasing the fidelity of grayscaled images in a diversified print environment. Owing to differences in microcode and toner fusing mechanisms, each model of print engine will render a grayscale image differently. Even identical printer models will render the same image differently from machine to machine due to wear, operating temperature, toner quality, and other factors. In the prior art two approaches were taken to insure consistent results in a multiple printer environment: modify data generating applications to produce a different image for each output device, or apply a data transform with a threshold array and calibration curve to produce corrected images. The first approach is excessively burdensome to end users of the print environment, who may not even be aware of how the print environment is configured. The second approach requires technology created by IBM specifically for Advanced Function Printing (AFP) environments, restricting its use to printers that support the Intelligent Printer Data Stream (IPDS) [1]. By presenting a virtual printer as an IPDS proxy, a heterogeneous network of printers at various quality levels and accepting any variety of printer languages can create homogenized and high fidelity output without modification to any user application.

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  Method and Apparatus for rendering Grayscales at a printing device using a calibrated threshold matrix via the Virtual Printer.

   Described is a method for increasing the fidelity of grayscaled images in a
diversified print environment. Owing to differences in microcode and toner
fusing mechanisms, each model of print engine will render a grayscale image
differently. Even identical printer models will render the same image
differently from machine to machine due to wear, operating temperature, toner
quality, and other factors. In the prior art two approaches were taken to insure
consistent results in a multiple printer environment: modify data generating
applications to produce a different image for each output device, or apply a data
transform with a threshold array and calibration curve to produce corrected
images. The first approach is excessively burdensome to end users of the print
environment, who may not even be aware of how the print environment is
configured. The second approach requires technology created by IBM specifically
for Advanced Function Printing (AFP) environments, restricting its use to
printers that support the Intelligent Printer Data Stream (IPDS) [1]. By
presenting a virtual printer as an IPDS proxy, a heterogeneous network of
printers at various quality levels and accepting any variety of printer languages
can create homogenized and high fidelity output without modification to any user
application.

   A typical embodiment is depicted in Figure 1. When
a job is scheduled by print management system 100, the
threshold array and calibration curves appropriate to
the model or instance of printer can be sent to data
format transform 101 along with the application data.
A wide variety of datastreams may be converted into
Mixed Object Document Content Architecture (MODCA) [2]
by data format transform 101. The data formats listed
in the figure are illustrative, not intended as a
comprehensive list. Print management system 100
converts MODCA into IPDS. Value added in MODCA may
include impositioning instructions and...