  Wavefront shaping allows focusing light through or inside strongly scattering
media, but the background intensity also increases due to long-range
correlations, reducing the target's contrast. By manipulating non-local
intensity correlations of scattered waves in a disordered system with input
wavefront shaping, we create high-contrast patterns behind strongly scattering
media and targeted energy delivery into a diffusive system with minimal change
in the surrounding intensity. These are achieved by introducing the contrast
operator and the difference operator, and utilizing their eigenstates to
maximize the target-to-background intensity contrast and energy difference.
This work opens the door to coherent control of non-local effects in wave
transport for practical applications.
