Allred Sarah R, Radonjic Ana, Gilchrist Alan L, Brainard David H
Department of Psychology, Rutgers, The State University of New Jersey, Camden, NJ, USA.
J Vis. 2012 Feb 8;12(2):10.1167/12.2.7 7. doi: 10.1167/12.2.7.
We measured the perceived lightness of target patches embedded in high dynamic range checkerboards. We independently varied the luminance of checks immediately surrounding the test and those remote from it. The data establish context transfer functions (CTFs) that characterize perceptual matches across checkerboard contexts. Several features of the CTFs are broadly consistent with previous research: Matched luminance decreases when overall context luminance decreases; matched luminance increases when overall context luminance increases; manipulating context locations near the target has a greater effect than manipulating locations far from the target patch. The measured CTFs are not well described, however, by changes with context in multiplicative gain alone or by changes in both multiplicative and subtractive adaptation parameters. We were able to fit the data with a three-parameter model of adaptation. This allowed us to characterize the CTFs by specifying the luminances that appeared white, black, and gray (white point, black point, and gray point, respectively). The white and black points depended additively on the local and remote contrasts, but accounting for the gray point required an interaction term. Analysis of this effect suggests that the target patch itself must be included in a description of the visual context.
我们测量了嵌入高动态范围棋盘格中的目标色块的感知亮度。我们分别改变紧邻测试色块的方格以及远离测试色块的方格的亮度。这些数据建立了上下文传递函数（CTF），该函数表征了跨棋盘格上下文的感知匹配。CTF的几个特征与先前的研究大致一致：当整体上下文亮度降低时，匹配亮度降低；当整体上下文亮度增加时，匹配亮度增加；操纵目标附近的上下文位置比操纵远离目标色块的位置具有更大的影响。然而，单独的乘法增益随上下文的变化或乘法和减法适应参数的变化都不能很好地描述所测量的CTF。我们能够用一个三参数适应模型来拟合数据。这使我们能够通过指定呈现白色、黑色和灰色的亮度（分别为白点、黑点和灰点）来表征CTF。白点和黑点分别取决于局部和远程对比度，但要解释灰点则需要一个交互项。对这种效应的分析表明，目标色块本身必须包含在视觉上下文的描述中。
