Color Correction - Nuke 101: Professional Compositing and Visual Effects - page 182

26. Do the same from the Maximum Luminance Pixel value to Gain ( FIGURE 4.35 ) .
Figure 4.35. Dragging while holding Ctrl/Cmd creates a linking expression.
You have now matched the foreground's shadows and highlights to those of the
background ( FIGURE 4.36 ).
Figure 4.36. Shadows and highlights now match.