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Quantification and Standardized Description of Color Vision Deficiency Caused by Anomalous Trichromats-Part I: Simulation and Measurement

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Quantification and Standardized Description of Color Vision Deficiency Caused by Anomalous Trichromats-Part I: Simulation and Measurement UC Irvine UC Irvine Previously Published Works Title Quantification and Standardized Description of Color Vision Deficiency Caused by Anomalous Trichromats-Part I: Simulation and Measurement Permalink https://escholarship.org/uc/item/91g0z1x8 Journal EURASIP Journal on Image and Video Processing, 2008 ISSN 1687-5176 1687-5281 Authors Yang, Seungji Ro, Yong Man Wong, Edward K et al. Publication Date 2008 DOI 10.1155/2008/487618 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Hindawi Publishing Corporation EURASIP Journal on Image and Video Processing Volume 2008, Article ID 487618, 9 pages doi:10.1155/2008/487618 Research Article Quantification and Standardized Description of Color Vision Deficiency Caused by Anomalous Trichromats—Part I: Simulation and Measurement Seungji Yang,1 Yong Man Ro,1 Edward K. Wong,2 and Jin-Hak Lee3 1 Image and Video Systems Lab, Information and Communications University, Munji 119, Yuseong, Daejeon 305-732, South Korea 2 Department of Ophthalmology, University of California at Irvine, Irvine, CA 92697-4375, USA 3 Department of Ophthalmology, Seoul National University Hospital, 28 Yongon-Dong, Chongno-Gu, Seoul 110-744, South Korea Correspondence should be addressed to Yong Man Ro, [email protected] Received 8 October 2007; Revised 14 December 2007; Accepted 22 December 2007 Recommended by Alain Tremeau The MPEG-21 Multimedia Framework allows visually impaired users to have an improved access to visual content by enabling content adaptation techniques such as color compensation. However, one important issue is the method to create and interpret the standardized CVD descriptions when making the use of generic color vision tests. In Part I of our study to tackle the issue, we present a novel computerized hue test (CHT) to examine and quantify CVD, which allows reproducing and manipulating test colors for the purposes of computer simulation and analysis of CVD. Both objective evaluation via color difference measurement and subjective evaluation via clinical experiment showed that the CHT works well as a color vision test: it is highly correlated with the Farnsworth-Munsell 100 Hue (FM100H) test and allows for a more elaborate and correct color reproduction than the FM100H test. Copyright © 2008 Seungji Yang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1. INTRODUCTION there is no satisfactory cure for CVD and this condition is lifelong. However, there has been a little consideration about Today, the use of color display in the multimedia-enabled any assistance to people with CVD in color perception. devices is very common. Portable multimedia devices even Recently, universal multimedia access (UMA) has be- allow real-time displays of high-quality color information. come an emerging trend in the world of multimedia commu- As such, with the proliferation of color displays, it becomes nication. A UMA system adapts rich multimedia content to more important for ordinary people to perceive colors cor- various constraints imposed by users, devices, and networks, rectly. Color displays create no problems for normal people, providing the best possible multimedia experience to a par- although color perception might be slightly different among ticular user, anytime and anywhere. Meanwhile, the recently different people with a different normal color vision. Mean- developed MPEG-21 multimedia framework facilitates the while, color displays do cause problems for people with color realization of UMA systems in an interoperable manner [2]. vision deficiency (CVD). For these people, the use of rich col- Among other tools that enable seamless access to multime- ors may lead to confusion. It may even result in misinterpret- dia, the MPEG-21 multimedia framework provides a norma- ing information that colors are carrying because people with tive description of CVD. In this way, visually impaired users CVD may suffer from inability to discriminate among differ- can have improved access to visual content through content ent colors. The problem even gets worse in cases where color adaptation, more specifically by means of color compensa- is the only visual clue to recognize something important. tion. In this context, the color compensation process can be Up to 8% of the world’s male population exhibits a type guided and optimized by the CVD description standardized of CVD. More than 80% of them has one form of anoma- by the MPEG-21 [2, 3]. lous trichromacy, which demonstrates a milder and variable However, to suitably accommodate color compensa- severity than those with dichromacy [1]. It is known that tion using the CVD description provided by the MPEG-21 2 EURASIP Journal on Image and Video Processing multimedia framework, two important issues should be re- be discolored or changed due to contamination over time. solved. The first issue consists of matching CVD characteris- Due to these problems, although the FM100H test is known tics to the MPEG-21 CVD description, while the second issue to be the most accurate clinical test, it has been less com- consists of the design of a content adaptation scheme that is monly used than many other tests. harmonized with the MPEG-21 CVD description. In this pa- Several studies have been done to simplify the analysis per, in order to tackle these two issues, we present a compre- of the results of the FM100H test [6, 11, 13]. In this study, hensive study that examines CVD through a computerized we present an alternative approach by considering a comput- color vision test (referred to as CHT), utilizes color compen- erized color vision test. Color vision testing using the com- sation techniques through anomalous cone modeling, and puter has a number of important advantages. In using the quantifies color vision defects using a new computerized hue computer and monitor after calibration, any color can be eas- test (CHT) with color compensation. ilyreproducedaswellaschangedforspecificpurposes.The The major contribution of Part I of our study is the devel- test and resulting data can be easily managed, analyzed, and opment of a reproducible, computer-based color vision test, shared. Modifications and improvements of the test method called the CHT. The fundamental idea behind the CHT stems are also possible if necessary. from generic color arrangement tests such as the Farnsworth- Munsell 100-Hue (referred to as FM100H) test. One ma- 3. COMPUTERIZED HUE TEST FOR COLOR ff jor di erence is the fact that the CHT is a reproducible and VISION DEFICIENCY computer-based test, which allows easy manipulation of test colors for the purposes of simulation and analysis of anoma- 3.1. Color vision deficiency lies in color vision. In Part I of our study, we have also com- pared the efficiency of the CHT to the FM100H test. A com- A significant number of studies have been conducted to puter simulation is used to study the variation of color de- understand human color perception and cone fundamen- fects according to the spectral cone shift. Finally, in Part II tals [14–20]. Normal color vision has three cones whose of our study, we will discuss a color compensation scheme peak sensitivities lie in the long-wavelength (L), middle- for anomalous trichromats. This color compensation scheme wavelength (M), and short-wavelength (S) bands of the vis- operates according to the deficiency degree standardized by ible spectrum [1, 19]. Meanwhile, CVD arises from two the MPEG-21 multimedia framework. causes: (1) complete lack of a cone pigment or (2) alteration of one of the three cone pigments. The former is known as 2. RELATED WORK: CONVENTIONAL COLOR dichromacy, and the latter is known as anomalous trichro- VISION TESTS macy. There is an extreme case, called achromatopsia, where no cone is present in the eyes. Anomalous trichromacy is In order to examine anomalies in color vision, many clinical known to have various causes [1].Themostfrequentone color vision tests were developed several decades ago. In gen- is the shifting of cone spectral sensitivity from the normal eral, two major test methodologies have been developed: one position [1, 15, 17, 21]. Anomalous trichromats have three is related to the colors reflected from a colored object, while classes of cone pigments, but the peak sensitivity wavelengths the other is related to the colors emitted from a solid light of two of these classes lie closer together. Depending on source. The tests using reflected light are subdivided into two the type of shifted cone, anomalous trichromacy is divided types: one type is the pseudoisochromatic plate tests such as into protanomalous (having a shifted L cone), deuteranoma- the Ishihara test [4, 5] and the Hardy-Rand-Rittler (HRR) lous (having a shifted M cone), and tritanomalous (having a test [6], while the other type is the color arrangement testing shifted S cone) trichromacy. The protanomalous and deuter- such as the Farnsworth Panel D-15 test and the FM100H test anomalous trichromats are X-chromosome-linked, genetic, [7–9]. The test using emitted colors includes several types of anomalous trichromats, while the tritanomalous trichromats anomaloscopes developed by Jyrki [10]. aremostlyacquired.Duetoabnormalconecharacteristics, Among all of the tests, the FM100H test is known to be people with CVD may have great difficulty with color dis- one of the most accurate tests showing high sensitivity to find crimination. color defects at an early stage and to determine the degrees of severity. The FM100H test has the subject place 85 differ- 3.2. Implementation of the computerized hue test ent color caps in a specific order. The color caps are divided into four groups, each of which comprises 22, 21, 21, and 21 The CHT is a kind of color arrangement test. It is designed color caps, respectively. The type of CVD and its severity de- to display several color caps with different colors on a black gree are determined by the location of the caps after testing.
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