Subfield Coding Research Articles

AssignFAST: An Autosuggest based tool for FAST Subject Assignment

Subject assignment is really a three-phase task. The first phase is intellectual—reviewing the material and determining its topic. The second phase is more mechanical, identifying the correct subject heading(s). The final phase is retyping or cutting and pasting the heading(s) into the cataloging interface along with any diacritics, and potentially correcting formatting and subfield coding. If authority control is available in the interface, some of these tasks may be automated or partially automated.
 A cataloger with a reasonable knowledge of FAST[i],[ii] or even LCSH[iii] can quickly get to the proper heading, but usually needs to confirm the final details—was it plural? Am I thinking of an alternate form? Is it inverted? Etc. This often requires consulting the full authority file interface. assignFAST is a Web service that consolidates the entire second phase of the manual process of subject assignment for FAST subjects into a single step based on autosuggest technology.
 
 
 [i] Chan, Lois Mai and Edward T. O'Neill. FAST: Faceted Application of Subject Terminology, Prnciples and Applications Libraries Unlimited, Santa Barbara, 2010.http://lu.com/showbook.cfm?isbn=9781591587224.
 
 
 [ii] OCLC Research Activities associated with FAST are summarized at http://www.oclc.org/research/activities/fast/
 
 
 [iii] Chan, Lois M. Library of Congress Subject Headings : Principles and Application: Principles and Application. Westport, Conn: Libraries Unlimited, 2005.
 

采用自适应有限灰度级子场编码方法提高等离子体显示器的显示质量

To improve the dynamic and static image quality,a new adaptive limited grays subfield coding method based on histogram equalization was proposed.In this method,a new probability density distribution was obtained by image histogram equalization.The gray scales were divided uniformity according to the number of subfield,and the grays in middle of each sub-section as the pre-sample grays were selected.The sample grays and subfield coding were obtained through the inverse transformation of histogram equalization.A subfield was set to zero for one gray coding to get the better image quality.Simulation results show that the proposed method has the advantages of simple-accumulation and combination lighting modes.It can improve the dynamic false contrast and gray scales expression simultaneously.

P‐88: Surface‐Based Adaptive Incremental Subfield Coding Method for Plasma Display Panels

AbstractThis paper proposes a new incremental subfield coding method using region segmentation for plasma display panels (PDPs). The proposed approach suppresses the halftone noise (HN) of the PDPs, while completely eliminating false contour noise (FCN), as do existing incremental subfield codes, by selecting an optimal incremental subfield code adaptively for a given input image. The proposed method selects the HN sensitive pixels using region segmentation and maps the problem of selecting the optimal incremental subfield code onto a special‐case shortest path problem.

Image-based dynamic subfield coding for improving gray scale smooth in color PDPs

Dynamic subfield coding (DSC) based on uniform sample and symmetrical segmentation for valid gray scales is proposed to resolve the lack of gray scale expression capability for static images in accumulation light emission mode. In this method, gray scale is sampled in isolated gray region, then gray scales left is segmented symmetrically and gray scales with higher histogram can be sampled in each gray region segmented. The subfield weight is the difference of adjacent sampled gray scales. So the gray scales sampled is distributed symmetrically, the gray scales sampled and subfield weight is varied according to the image. The simulation and experiment results show that the proposed method can not only express the large area background perfectly, but also keep the image details furthest and reduce the contour of static image.

An Improved Adaptive Subfield Coding Method for Driving AC PDPs

An improved adaptive subfield coding driving method was proposed to reduce the static false contours when the simple-accumulation lighting mode is applied to alternating current plasma display panels (ac PDPs). In the proposed method, when the weighted ratio of the subgrayscale interval to the main grayscale interval is smaller, the gray cumulative probability densities in the subgrayscale interval are sampled in order to locate the sampling gray levels at which the gray probability densities are larger. When the weighted ratio of the subgrayscale interval to the main grayscale interval is larger, the gray levels in the subgrayscale interval are sampled directly so as not to generate larger quantization error brought by the excessive convergence of the sampling gray levels. The simulation results show that the proposed method can eliminate the dynamic false contours in the AC PDPs and has better grayscale expression capability than the existing similar method appearing in the literature. The method proposed in this paper can reproduce the original image information more faithfully.

Error Propagation Algorithm for Reduction of Errors Due to Total Load and Line Load in a Plasma Panel Display

The displayed gray level of a plasma display panel (PDP) is often different from the intended target gray level because the displayed level is affected by the load of the panel. The effect of the load on the displayed gray level is decomposed into three factors: total load; line load magnitude; and line load distribution. Previous attempts to reduce this difference (i.e., error) have achieved only limited success because they have not taken three factors into consideration altogether. This paper proposes a new method that compensates for the error caused by all three factors. The proposed method first attempts to compensate for the error caused by line load magnitude and distribution. To this end, the error generated by one sub-field of a PDP is propagated to and compensated for by the remaining sub-fields. The amount of the error is reduced for every incidence of error propagation and, consequently, the final amount of error is reduced to a negligible level. To reduce the computational complexity for the evaluation of the amount of the error caused by the line load distribution, an iterative method is proposed to derive the effect of line load distribution on each cell from its adjacent cell. When sub-field coding is completed for a whole cells on a panel, total load of each sub-field is obtained and the error caused by total load is compensated for by controlling the number of sustain pulses for each sub-field. A significant error reduction is achieved, which shown by simulations and experiments with a 42-in. PDP set, including 91.2% reduction of the mean absolute error obtained through simulations and 69.7% reduction of luminance variation range caused by the load variation in experiments.

Reduction of halftoning errors due to line load in a plasma display panel

The displayed gray level of a plasma display panel (PDP) is often different from the intended target gray level because the displayed level is affected by line load (the number of on-cells in a scan line). Previous attempts to reduce this difference (i.e. error) have been applicable to PDPs with no constraint imposed on the on-off decision for each sub-field. In order to improve the image quality (e.g. dynamic false contour (DFC) reduction), recently-developed PDPs impose constraints on sub-field coding and reduce the number of gray levels. This paper proposes a new sub-field coding algorithm that compensates for level error caused by the load when constraints are imposed on sub-field coding. As the number of gray levels is reduced, halftoning is employed in order to represent intermediate gray levels. In the proposed algorithm, the magnitude of the level error caused by the load effect is predicted and then two levels that are used for the halftoning are modified to compensate for the error. The modified levels are the nearest levels to the input level among the levels that satisfy the constraint of the sub-field coding. In order to reduce errors with moderate computational complexity, error prediction and level update are repeated by twice. A significant error reduction is achieved and shown by simulation and experimentation using a 42-inch PDP, including a 93.5% reduction in the mean absolute error (MAE) in simulations and a 67.2% reduction in MAE in experiments on a PDP.

A Subfield Coding Algorithm for the Reduction of Gray Level Errors Due to Line Load in a Plasma Display Panel

Displayed gray level of a plasma display panel (PDP) is often different from the intended target gray level due to the variation of the line load (the number of on-cells on a scan line). The conventional gray level generation algorithm does not take this difference into consideration and may deteriorate the displayed image quality. In this paper, luminance ratio variations that depend on the line load are formulated as the third-order regression equations for red, green and blue colors, respectively. Based on these equations, this paper proposes a new gray-level generation algorithm to reduce gray-level errors caused by the variation of the line load. The proposed algorithm performs the conventional algorithm three times with new weight vectors (i.e., the expected gray levels of subfields) adjusted based on the detected error of the previous run of the conventional algorithm. Simulations and experiments with a 50-in PDP show significant error reductions, including a 75.6% improvement of the mean absolute error evaluated with nine video sequences.

Image Adaptive Incremental Subfield Coding for Plasma Display Panels

In this letter, we propose a new approach to incremental coding of the subfield codes for plasma display panels (PDPs). The proposed approach suppresses the halftone noise of the PDPs, while completely eliminating false contour noise, as do existing incremental subfield codes, by selecting an optimal incremental subfield code adaptively for a given input image. The proposed method maps the problem of selecting the optimal incremental subfield code onto a special-case shortest path problem. Results of experiment using 109 sample images illustrated that the proposed method improved the average peak signal-to-noise ratio by 4.4-6.2 dB in halftone noise compared with existing incremental subfield coding methods.

An adaptive subfield coding method for driving AC PDPs

The image quality suffers from the lack of grayscale expression capability when the simple accumulation of light emission is applied to express grayscale in alternating current plasma display panels (ac PDP). To solve the problem, an adaptive subfield coding (ASC) method for driving ac PDP is proposed, in which subfield vector is adaptively figured out based on the normalized histogram of input image every television field. The calculated subfield vector can express the most grayscale information of input image. And then the number of sustain pulses in each subfield is adjusted according to the calculated subfield vector. Simulation results show that the proposed method can eliminate the dynamic false contours in ac PDPs and overcome the lack of grayscale expression capability caused by the simple-accumulation-lighting-mode. It could provide good grayscale expression in ac PDPs.

High-performance 55-in. diagonal WXGA PDP with extended ALIS technology

— We have developed a high-performance 55-in. diagonal WXGA PDP module with a novel structure by using Extended ALIS (Alternate Lighting of Surfaces) technology. The new cell structure that uses the common bus electrode concept was invented with a new driving scheme aimed toward progressive lighting. A new method of reducing dynamic false contour (DFC), motion adaptive subfield coding, was also developed. The newly developed 55-in. WXGA panel has a 1000-cd/m2 peak luminance and a 160-cd/m2 full-screen white luminance with a 9000 K color temperature at a 350-W display power consumption.