用伪同色光谱图像检测色觉正常观察者的锥细胞光谱响应

The Spectral Pseudoisochromatic Images for Testing Retinal Cone Spectral Responses of Observers with Normal Color Vision

为了能够快速、准确的检测色觉正常观察者的辨色差异,从而对其红、绿、蓝三通道的锥细胞光谱响应进行研究,设计并制作了由背景层(或和明度层)以及数字层组成的伪同色光谱图像,其中背景层和数字层具有不同的光谱反射曲线,经过照明光源以及人眼锥细胞光谱响应的共同作用,使色觉正常的观察者产生不同的颜色感知差异。实验首先基于不同光谱原色的输出设备,在不同的照明光源下,制作出能够放大观察者差异的近同色异谱色样对。要求用不同颜色匹配函数计算近同色异谱色样对的CIEDE2000色差值,有的色差在人眼辨色阈值之内,有的色差人眼可明显识别。通过优化计算,将放大观察者色觉差异的近同色异谱色样对应用于伪同色光谱图像的数字层和背景层,并利用Epson Stylus Pro7908喷墨打印机和OKI C9600激光打印机分别输出伪同色光谱图像的背景层和数字层。同时组织了72名色觉正常的观察者(包含55名18~25岁的年轻观察者和17名62~74岁的老年观察者)分别在D65和LED-5000K两种光源下,对伪同色光谱图像进行识读检验。识读结果表明,伪同色光谱图像可以较为准确的判定年轻和老年观察者的视网膜锥细胞光谱响应是否老化。同种照明光源下,年轻观察者可以识读出数字的伪同色光谱图像(②/④)老年观察者不能识读,老年观察者可以识读的伪同色光谱图像(①/③)大多年轻观察者不能识读,且55名年轻观察者中有4名观察者的目视结果与老年人相同。另外,年轻观察者的锥细胞光谱响应与CIE1964和CIE2006(age=25 y)颜色匹配函数较为一致,而老年观察者的锥细胞光谱响应与CIE1931和CIE2006(age=75 y)颜色匹配函数更为一致。对比颜色匹配函数的分布,发现老年观察者的锥细胞光谱响应向长波段偏移,同时由于屈光系统光学密度增加导致其锥细胞光谱响应有所降低。

In order to test the variability in color discrimination among observers with normal color vision and study the spectral responses of cone cells in R,G,B three channels,the spectral pseudoisochromatic images consisting of background layer,lightness layer and number layer,which have different spectral reflectance were designed and created.By interacting with the light source and the spectral response of the human cone cells,different observers perceive various color differences.The obtained visual results were used to further study the difference of human perception on the metameric color pairs.The experiments were based on different output equipments with different primary inks producing different spectral reflectances,and the metameric color pairs were created under different light sources,which can amplify the observer’s variability.For the CIEDE2000 color difference calculated by different color matching functions,some were within the threshold of color discrimination,and some could be clearly recognized.By optimizing calculation,the nearly metameric color pairs,which can magnify the color discrimination of observers,were applied to design the number and background layers of the spectral pseudochromatic image.The Epson inkjet printer and OKI laser printer were used to print the number layer and background layer of the pseudochromatic spectral image correspondingly.72 color-normal observers,including 55 young observers aged from 18 to 25 and 17 old observers aged from 62 to 74,were organized to view and test the images under D65 and LED-5000K light sources respectively.The visual results showed that the spectral pseudochromatic images can be successfully used to classify whether the spectral response of retinal cone cells is aging or not.Under the same light source,young observers can read the numbers in images (②/④) that the old observers can’t read,while the old observers can read the numbers in images (①/③) that most young observers can’t read,and 4 of the 55 young observers have the same visual results as the elderly.In addition,the spectral responses of young observers were consistent with the CIE1964 and CIE2006 (age=25 y) Color Matching Functions(CMFs),while the spectral response of old observers were more consistent with the CIE1931 and CIE2006 (age=75 y) CMFs.It was found that the cone cell spectral responses of old observers were shifted to the long wavelength,and the spectral responses decreased due to the increase of the optical density of the ocular system.