Victor Loewen

A web-based troubleshooting tool to help customers self-solve color issues with a digital printing workflow

Current printing technologies enable customers to reproduce high quality, realistic, and colorful hard copies of their digital documents. Although the activity of printing is transparent to the customers, the progression of a customers document through the color printing workflow (CPW) is a complex process that may alter the colors in the print job. Given the complexity of the CPW, it is a difficult problem to diagnose the source of the color issue. Novel tools and methods that address this challenge are beneficial for both the manufacturer and its customers. We propose a Web-based troubleshooting tool that helps customers to self-solve color issues with electrophotographic laser printers when printing solid colors in graphics and text. The tool helps the customer to reconfigure his/her CPW following printing best practices. If the issue is still unresolved, the tool guides the user to search the gamut of the printer for his/her color preference. The usability of the tool was carefully evaluated with human subject experiments. Also, the description and organization of the troubleshooting tasks were continuously reviewed and improved in regular meetings of the development team. In this paper, we describe the troubleshooting strategy, the color preference search algorithm, and the results of the usability experiments.

Halftone blending between smooth and detail screens to improve print quality with electrophotographic printers

In this paper, we consider a dual-mode halftoning process for the electrophotographic laser printer - a low frequency halftoning for smooth regions and a high frequency halftoning for detail regions. These regions are described by an object map that is extracted from the page description language (PDL) version of the document. This manner of switching screens depending on the local content provides a stable halftone without artifacts in smooth areas and preserves detail rendering in detail or texture areas. However, when switching between halftones with two different frequencies, jaggies may occur along the boundaries between areas halftoned with low and high frequency screens. To reduce the jaggies, our screens obey a harmonic relationship. In addition, we implement a blending process based on a transition region. We propose a nonlinear blending process in which at each pixel, we choose the maximum of the two weighted halftones where the weights vary according to the position in the transition region. Moreover, we describe an on-line tone-mapping for the boundary blending process, based on an off-line calibration procedure that effectively assures the desired tone values within the transition region.

Houston, we have a color issue!

Todays color imaging systems are powerful and complex entities that enable users to replicate lifelike colors. However when a color issue arises, it is very difficult to diagnose and solve. Therefore, it is beneficial to complement a color imaging system with sophisticated and user-friendly tools that help users to self-solve color issues. This paper discusses the assessment of a color printing workflow (CPW) for personal computers and the development of a web-based self-service customer support tool for color printing issues that may arise with electrophotographic color printers. We study the stages in the CPW where the colors of a document may change. From this evaluation, we find the system configuration that may have caused the change. This study provides the foundation for the development of our web-based tool, named the Color Printing Workflow Troubleshooting (CPWT) Tool. This comprehensive assessment of the CPW helps us to determine a troubleshooting strategy for our web-based tool. The set of color issues considered are those that arise when one attempts to reproduce a Pantone spot color.