Exactly. Let's say cops stop 10% of blacks for "looking suspicious" (aka, being black), but only 1% of whites.
Now say that 10% of both whites and blacks are criminals. And they always get identified if stopped, and eventually arrested and sentenced. An that the population is evenly split between blacks and whites.
(1) Criminal prevalence: 50% B, 50% W
(2) Police stops: 91% B, 9% W
(3) Criminals caught (reports): 91% B, 9% W
(4) Incarceration: 91% B, 9% W
Now remember that only (3) and (4) are available to the public, so one might look and say that the problem isn't that blacks are incarcerated differently, but that blacks commit more crimes, when they don't.
[1] https://en.wikipedia.org/wiki/Driving_while_black