DS90CF364A: LVDS to RGB 18 bit clarification

Hi,

We need to convert LVDS to RGB, 

For LVDS signal we have 

LVDS0_TX0_N
LVDS0_TX0_P

.

.
.
LVDS0_TX3_DN
LVDS0_TX3_DP

4 pair of input are there as above.

We need to convert LVDS to RGB (18 bit), but in DS90CF364A there is only 3 pairs inputs. Who can we connect remaining pair pins of LVDS to  DS90CF364A?

or do we need to use DS90CF384A which has 4 pair of LVDS inputs? If we use DS90CF384A the RGB output will be 24 bits (8*Red,8*Green,8*Red).

We need 18 bit (6*Red,6*Green,6*Red). Please help us to resolve the issue.