Department of Information and Communications Engineering, Tokyo Institute of Technology, 4259-G2-1 Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan.
Department of Information and Communications Engineering, Tokyo Institute of Technology, 4259-G2-1 Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan.
Vision Res. 2022 Jul;196:108028. doi: 10.1016/j.visres.2022.108028. Epub 2022 Mar 2.
In conventional psychophysical reverse correlation methods using white or pink noise, the luminance noise is added to every pixel. Thus, the image features correlated with perception are often biased toward local mean luminance. Furthermore, spatial frequencies and orientations are represented in the primary visual cortex, which forms the basis of various visual perception. In this study, we proposed a new reverse correlation method using noise that modulated the spatial frequency sub-band contrast and examined its properties in psychophysical experiments on facial skin lightness perception. In the experiment, we asked the observers to compare the perceived skin lightness in a paired comparison manner on face stimuli with increased or decreased spatial frequency sub-band contrasts at random spatial locations. The results showed that the contrasts in the eyes or irises were strongly and positively correlated with the perceived skin lightness in most sub-bands, demonstrating that the proposed method reiterated the findings of previous studies that the sparkle of the irises makes the skin appear lighter. Contrarily, the conventional reverse correlation method using pink noise images was applied to the skin lightness perception. The results indicated that only the local mean luminance in some skin regions, such as the forehead, was correlated with skin lightness perception. In summary, with the proposed method, we found some image features in the facial parts other than the skin mean luminance relevant to skin lightness perception, which are difficult to detect using the conventional method. They are considered complementary given that the proposed method and the conventional method extracted considerably different image features. It depends on the psychophysical tasks and stimuli which one is more appropriate.
在使用白噪声或粉红噪声的传统心理物理学反向关联方法中，亮度噪声会被添加到每个像素。因此，与感知相关的图像特征往往偏向于局部平均亮度。此外，空间频率和方向在初级视觉皮层中得到表示，初级视觉皮层是各种视觉感知的基础。在这项研究中，我们提出了一种使用噪声调制空间频率子带对比度的新的反向关联方法，并在面部皮肤亮度感知的心理物理实验中检验了其性能。在实验中，我们要求观察者以配对比较的方式比较面部刺激中随机空间位置增加或减少空间频率子带对比度时的感知皮肤亮度。结果表明，在大多数子带中，眼睛或虹膜的对比度与感知皮肤亮度强烈正相关，这表明该方法重复了先前研究的发现，即虹膜的闪烁使皮肤看起来更亮。相反，使用粉红噪声图像的传统反向关联方法被应用于皮肤亮度感知。结果表明，只有前额等一些皮肤区域的局部平均亮度与皮肤亮度感知相关。总之，通过提出的方法，我们发现了一些与皮肤亮度感知相关的面部部位的图像特征，而这些特征是使用传统方法难以检测到的。鉴于提出的方法和传统方法提取了相当不同的图像特征，它们是互补的。这取决于心理物理任务和刺激，哪种方法更合适。
