Figure 1.

The two original paintings, the Blue Boy (O1) and La Source (O2), were split into their luminance components (L1, L2) and their color components (C1, C2; second row). These were recombined, and transparently superimposed, into two frames (third row). Frame 1 contained both color pictures plus L1, and frame 2 contained both color pictures plus L2. Result: The luminance pictures dominated and gated the colors, so Frame 1 looked like the Blue Boy, while Frame 2 looked like La Source (see Figure 2).