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首页> 外文学位 >Psychophysics study and reduction of banding artifact in secondary colors using an embedded implementation of closed-loop control on multiple motion systems in an electrophotographic process.
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Psychophysics study and reduction of banding artifact in secondary colors using an embedded implementation of closed-loop control on multiple motion systems in an electrophotographic process.

机译：心理物理学研究和在电子照相过程中使用对多个运动系统的闭环控制的嵌入式实现，减少了二次色中的条带伪影。

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摘要

Banding is a common print artifact, which shows as quasi-periodic contrast, hue, and saturation variations. Motion quality of moving components in a laser printer, such as speed fluctuation of photoconductor drums and laser beam vibrations, have been shown to be a major contribution factor to the occurrence of banding. The human visual system's contrast sensitivity threshold is often used as the detection threshold model for banding perception. On color electrophotographic (EP) platforms, due to multiple primary color layers being superimposed together, banding patterns in these different layers may interact and be perceptible. As a result, color banding appears as quasi-periodic hue or lightness gratings. In the literature, work has been done in studying human visual perception of hue variations in isoluminance conditions. However, in a color electrophotographic process, when multiple primary color layers superimpose, they may not necessarily be isoluminant. In addition, because banding is mainly caused by motion imperfections, to reduce the perception of banding, it is important to relate human visual response to banding to motion control variables. Hardcopy and softcopy psychophysics experiments were conducted to study perception of color banding characteristics. To use a printer to generate hardcopy psychophysics stimuli, an embedded closed-loop control system was implemented on the printer. The closed-loop control system effectively reduces the amplitude of the printer's intrinsic banding at multiple frequencies and allows extrinsic banding to be injected by controlling multiple motion systems. With the closed-loop control system, banding with frequencies that are Will integer and fraction multiples of the sampling frequencies can be reduced. The challenge of the implementation is to achieve performance while minimizing cost. The integration and design of the closed-loop control system is described. It was found that when banding in each of the primary colors is reduced to just below the detection thresholds, there is no guarantee that there will be no perceivable banding in secondary colors. To reduce banding in secondary colors, a tighter requirement for process control specification is needed than the simple reduction of banding in primary colors to just below individual perception thresholds. The hardcopy and softcopy experiments produced the same results when the same level of noise was included in the stimuli. The effect of the speed fluctuation of the photoconductor drums on the variations in the International Commission on Illumination's (CIE) L*a*b* is identified for different printed background levels. This mapping between the variations in the CIE L*a*b* and the drum speed fluctuation can convert the color banding detection thresholds obtained from softcopy psychophysics experiments to the process control specification requirement.
机译：条带是常见的打印伪影，显示为准周期对比度，色相和饱和度变化。激光打印机中移动部件的运动质量，例如光电导鼓的速度波动和激光束振动，已被证明是造成条带现象的主要因素。人类视觉系统的对比度敏感度阈值通常用作带状感知的检测阈值模型。在彩色电子照相（EP）平台上，由于多个原色层叠加在一起，这些不同层中的条纹图案可能会相互作用并且可以感知。结果，色带表现为准周期的色调或亮度光栅。在文献中，已经进行了研究人类在等亮度条件下对色调变化的视觉感知的工作。但是，在彩色电子照相方法中，当多个原色层重叠时，它们不一定是等离子发光体。另外，由于条带主要是由运动缺陷引起的，因此，为了减少条带的感觉，重要的是将人对条带的视觉响应与运动控制变量相关联。进行了硬拷贝和软拷贝心理物理学实验，以研究色带特征的感知。为了使用打印机生成硬拷贝心理物理学刺激，在打印机上实现了嵌入式闭环控制系统。闭环控制系统有效地降低了打印机在多个频率上固有条带的振幅，并通过控制多个运动系统允许注入外部条带。使用闭环控制系统，可以减少频率为采样频率的整数倍和分数倍的频带。实施的挑战是在最小化成本的同时实现性能。描述了闭环控制系统的集成和设计。已经发现，当将每种原色中的条带减少到恰好低于检测阈值时，不能保证在第二原色中不会有可察觉的条带。为了减少第二色中的条带，需要比简单地将原色中的条带减小到个体感知阈值以下的过程控制规范更严格的要求。当刺激中包含相同水平的噪声时，硬拷贝和软拷贝实验产生相同的结果。对于不同的印刷背景水平，确定了感光鼓的速度波动对国际照明委员会（CIE）L * a * b *的变化的影响。 CIE L * a * b *的变化与感光鼓速度波动之间的这种映射可以将从软拷贝心理物理学实验获得的色带检测阈值转换为过程控制规范要求。

著录项

  • 作者

    Chen, Mu-Chih.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 104 p.
  • 总页数 104
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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