Crosstalk is greatest at the bottom of the screen because of phosphor afterglow. One needs an especially light grey background there to counteract the strong crosstalk. One could have this light grey background uniform over the whole screen, making everything even more pastel. Or, toward the bottom of the screen one could have the grey background ramp up in brightness, which might be distracting. We chose a darker uniform background that allowed some crosstalk at the bottom of the screen.
Images often have little there anyway.
The subtracted estimated crosstalk appears as dark streaks. 2 balances the subtraction in Fig. The limited dynamic range of print film makes it hard to judge on paper. They also found that scanlines can be treated independently, although they really overlap slightly on the phosphor of the screen. They compensate with a 2-D lookup filter that depends on the actual luminance of the preceding pixel and the intended luminance of the present pixel.