Face-Based Luminance Matching: lumCompare2.tcl

The purpose of this program is to allow experimentation with face-based luminance matching, allowing arbitrary selection of the two colors that comprise the image. No files or information is read in or saved; this is entirely stand-alone.

The "Image:" radiobutton allows a choice between three different face images, and two non-face images. "MDB" stands for minimally distinct border, the luminance matching method that the paper used as a point of comparison. The first face image and the first MDB image were the ones used in the user study.

The top row of sliders allows selection of color "A", the foreground color in the left image, and the shadow color in the right image. The bottom row of sliders is for color "B". The color selection is in HLS space, the "double hexcone" of hue, lightness, and saturation. In both cases, the actual 8-bit RGB values which are used are displayed under the sliders.

By clicking inside the image and dragging left and right, the lightness coordinate of color "A" can be adjusted. Drag away from the positive face in order to bring the colors towards luminance match. Dragging inside the image offers much greater precision in setting the lightness than is possible with the small slider.

Once you've got one color matched with a gray, try varying the hue coordinate to see the extent of luminance variation of colors along the RGB rainbow. The face will appear on one side or the other depending on the contrast polarity between the face and the gray.

This program also allows you to compare the luminance of two colors, instead of just a color and a gray. This kind of color matching was not at all explored in the paper, but it could provide a transitivity test in the matching of various colors to gray.