Eric Maggard

Assessment of Presence of Isolated Periodic and Aperiodic Bands in Laser Electrophotographic Printer Output

Laser electrophotographic printers are complex systems with many rotating components that are used to advance the media, and facilitate the charging, exposure, development, transfer, fusing, and cleaning steps. Irregularities that are constant along the axial direction of a roller or drum, but which are localized in circumference can give rise to distinct isolated bands in the output print that are constant in the scan direction, and which may or may not be observed to repeat at an interval in the process direction that corresponds to the circumference of the roller or drum that is responsible for the artifact. In this paper, we describe an image processing and analysis pipeline that can effectively assess the presence of isolated periodic and aperiodic bands in the output from laser electrophotographic printers. In our paper, we will discuss in detail the algorithms that comprise the image processing and analysis pipeline, and will illustrate the efficacy of the pipeline with an example.

A general approach for assessment of print quality

Laser electrophotographic printers are complex systems that can generate prints with a number of possible artifacts that are very di_erent in nature. It is a challenging task to develop a single processing algorithm that can effectively identify such a wide range of print quality defects. In this paper, we describe an image processing and analysis pipeline that can effectively assess the presence of a wide range of artifacts, as a general approach. In our paper, we will discuss in detail the algorithm that comprises the image processing and analysis pipeline, and will illustrate the efficacy of the pipeline with a number of examples.

Local Defect Detection and Print Quality Assessment

Print quality is an important criterion for a printers performance. The detection, classification, and assessment of printing defects can reflect the printers working status and help to locate mechanical problems inside. To handle all these questions, an efficient algorithm is needed to replace the traditionally visual checking method. In this paper, we focus on pages with local defects including gray spots and solid spots. We propose a coarse-to-fine method to detect local defects in a block-wise manner, and aggregate the blockwise attributes to generate the feature vector of the whole test page for a further ranking task. In the detection part, we first select candidate regions by thresholding a single feature. Then more detailed features of candidate blocks are calculated and sent to a decision tree that is previously trained on our training dataset. The final result is given by the decision tree model to control the false alarm rate while maintaining the required miss rate. Our algorithm is proved to be effective in detecting and classifying local defects compared with previous methods.

Gloss uniformity measurement update for ISO/IEC 19751

To address the standardization issues of perceptually based image quality for printing systems, ISO/IEC JTC1/SC28, the standardization committee for office equipment chartered the W1.1 project with the responsibility of drafting a proposal for an international standard for the evaluation of printed image quality1. An ISO draft Standard2, ISO/WD 19751-1, Office Equipment - Appearance-based image quality standards for printers - Part 1: Overview, Procedure and Common Methods, 2004 describes the overview of this multi-part appearance-based image quality standard. One of the ISO 19751 multi-part Standard’s tasks is to address the appearance-based gloss and gloss uniformity issues (in ISO 19751-2). This paper summarizes the current status and technical progress since the last two updates3, 4. In particular, we will be discussion our attempt to include 75 degree gloss (G75) objective measurement5 in differential gloss and within-page gloss uniformity. The result for a round-robin experiment involving objective measurement of differential gloss using G60 and G75 gloss measurement geometry is described. The results for two perceptual-based round-robin experiments relating to haze effect on the perception of gloss, and gloss artifacts (gloss streaks/bands, gloss graininess/mottle) are discussed.

AUTONOMOUS DETECTION OF ISO FADE POINT WITH COLOR LASER PRINTERS

Image quality assessment is a very important field in image processing. Human observation is slow and subjective, it also requires strict environment setup for the psychological test 1. Thus developing algorithms to match desired human experiments is always in need. Many studies have focused on detecting the fading phenomenon after the materials are printed, that is to monitor the persistence of the color ink 2-4. However, fading is also a common artifact produced by printing systems when the cartridges run low. We want to develop an automatic system to monitor cartridge life and report fading defects when they appear. In this paper, we first describe a psychological experiment that studies the human perspective on printed fading pages. Then we propose an algorithm based on Color Space Projection and K-means clustering to predict the visibility of fading defects. At last, we integrate the psychological experiment result with our algorithm to give a machine learning tool that monitors cartridge life.

Differential gloss quality scale experiment update: an appearance-based image quality standard initiative (INCITS W1.1)

Surface characteristics of a printed sample command a parallel group of visual attributes determining perceived image quality beyond color, and they manifest themselves through various perceived gloss features such as differential gloss, gloss granularity, gloss mottle, etc. Extending from the scope of ISO19799 with limited range of gloss level and printing technologies, the objective of this study is to derive an appearance-based differential gloss quality scale ranging from very low gloss level to very high gloss level composed by various printing technology/substrate combinations. Three psychophysical experiment procedures were proposed including the quality ruler method, pair comparison, and interval scaling with two anchor stimuli, where the pair comparison process was subsequently dropped because of the concern of experiment complexity and data consistency after preliminary trial study. In this paper, we will compare the obtained average quality scale after mapping to the sharpness quality ruler with the average perceived differential gloss via the interval scale. Our numerical analysis indicates a general inverse relationship between the perceived image quality and the gloss variation on an image.