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.
Flatbed scanners have been adopted successfully in the measurement
of microscopic image artifacts, such as granularity and mottle, in
print samples because of their capability of providing full color, high resolution images. Accurate macroscopic color measurement relies on the use of colorimeters or spectrophotometers to provide a surrogate for human vision. The very different color response characteristics of flatbed scanners from any standard colorimetric response limits the utility of a flatbed scanner as a macroscopic color measuring device. This metamerism constraint can be significantly relaxed if our objective is mainly to quantify the color variations within a printed page or between pages where a small bias in measured colors can be tolerated as long as the color distributions relative to the individual mean values is similar. Two scenarios when converting color from the device <i>RG</i>B color space to a standardized color space such as <i>CIELab</i> are studied in this paper, blind and semi-blind color transformation, depending on the availability of the black channel information. We will show that both approaches offer satisfactory results in quantifying macroscopic color variation across pages while the semi-blind color transformation further provides fairly accurate color prediction capability.
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.
To address the standarization issues of perceptually based image quality for printing systems, ISO/IEC JTC1/SC28, the standarization committee for office equipment charactered the W1.1 project with the responsibiltiy of drafting a proposal for an international standard for the evaluation of printed image quality. One of the W1.1 task teams is charactered to address the issue of 'Gloss and Gloss Uniformity". This paper summarizes the current status and technical progress of this ad hoc team in 2003.
The amount of documents in electronic formats has dramatically increased because of the ease of information sharing. Hence, it is highly desirable to design an efficient document compression technique. In this paper, a divide-and-conquer technique is propose to classify a local region into uni-level, bi-level and multi-level classes. As a result, various compression approaches can be applied to suitable area to increase compression efficiency. The color sigma filtering technique is adopted as a preprocessing stage to facilitate the following segmentation and cluster validation processes. Experiment results demonstrate that this technique successfully dichotomize a color document into regions with similar characteristics.
Most commercially printed images are halftoned using a screening process. IN order to reproduce printed documents containing images, one usually performs descreening or inverse half toning to avoid possible moire patterns. There exists a variety of gray scale halftone descreening techniques in the literature. However, color halftone descreening is still an ongoing research topic. In this paper, we present two descreening approaches: suboptimal FIR filter and a two-stage color sigma filter. The suboptimal FIR descreening filter offers an efficient descreening approach for gray scale halftoned images. In the mean time, a color halftone descreening technique based on the color sigma filter does not assume any a priori knowledge about the half toning process, making it applicable to any color halftone image. Similar to the anisotropic diffusion algorithm and total variation minimization techniques designed for gray scale images, the color sigma filter is an O(N) algorithm which can smooth out variation within each region and preserve edge information in the RGB color space. When combined with halftone segmentation techniques, a complete document processing algorithm for gray-scale and color documents can be created.