Demo: varying the (optically mixed) lighting using sliders
Here is the MixIM 1.0 interface for a lighting matching experiment, presenting a stimulus image (left) and a probe (right). Three sliders below the probe represent the three canonical lighting modes, namely ambient, focus, and brilliance light, respectively. How a golf ball appeared under the corresponding light was shown next to each slider to give observers a purely visual reference about what each slider represents. The use of a golf ball as a light probe (Kartashova et al., 2015; Pont & Koenderink, 2007) was chosen because the texture gradients due to the surface structure of the golf ball helps to disambiguate the diffuseness and direction of the light (Xia et al., 2014).
In a matching experiment, a stimulus image is shown on the left. Observers’ task is then match the lighting in the probe image (at right) to the lighting in the stimulus, by moving the sliders that adjusting the weights of corresponding lighting mode.
The interface was developed using the graphic user interfaces features in MATLAB R2014a.
Fan Zhang, Huib de Ridder, Sylvia C. Pont; Asymmetric perceptual confounds between canonical lightings and materials. Journal of Vision 2018;18(11):11. doi: 10.1167/18.11.11.
Kartashova, T., de Ridder, H., te Pas, S. F., Schoemaker, M., & Pont, S. C. (2015). The visual light field in paintings of Museum Prinsenhof: Comparing settings in empty space and on objects. In B. E. Rogowitz, T. N. Pappas, H. de Ridder (Eds.), SPIE/IS&T Electronic Imaging (pp. 93941M–93941M). International Society for Optics and Photonics.
Pont, S. C., & Koenderink, J. J. (2007). Matching illumination of solid objects. Attention, Perception, & Psychophysics, 69 (3), 459–468.
Xia, L., Pont, S. C., & Heynderickx, I. (2014). The visual light field in real scenes. i-Perception, 5 (7), 613–629.