Confusion-line-guided hue-arrangement test for quantitative diagnosis of deutan color vision deficiency

With the advancement of display technologies and the widespread use of mobile devices, color vision tests have become accessible to the general public at a relatively low cost. Among the test methods, the hue-arrangement test is widely adopted for its simple operation and ability to map the physiological wavelength shift of cone sensitivity. However, constrained by conventional methodology in color cap selection, it is difficult to achieve high mapping accuracy, and the test process is time-consuming. In this paper, we propose a novel, to our knowledge, hue-arrangement test methodology based on a color cap selection strategy that follows the deutan confusion lines of color vision deficiency (CVD). In contrast to the conventional design, the colors within confusion lines have the advantage of greatly increasing the discrimination difficulty for deutan observers without affecting color normal observers (CNOs), resulting in a more accurate mapping relationship to the wavelength shift, defined here as the spectral shift between the peak sensitivities of the normal M cone and the anomalous M^' cone in deutan observers. Such a hypothesis was validated through human factor experiments. We adjusted combinations of individual confusion lines, luminance settings, and the number of caps to investigate the impact of these factors on time efficiency and diagnostic accuracy. Moreover, we compared the confusion effect of deutan versus protan confusion lines (Smith & Pokorny's version). The deutan lines demonstrated pronounced effects, whereas the protan lines showed minimal impact, which may be due to a combination of factors, including the risk of inaccuracy of the theoretical confusion line implemented. The findings of this study provide a more accurate and efficient methodology, which contributes to areas like CVD diagnosis, wavelength shift assessment, color enhancement, personalized color settings, etc.