An LCD display with an RGB interface, many displays of 3.5” and larger have this type of interface, can not be interfaced with a PIC directly.  In this case, the high voltage gate driver is built into the display. The 16-bit data bus may have 5 lines for R, 5 lines for B, and 6 data lines for G with additional signals for the clock and horizontal and vertical syncs. This interface is a fully digital interface and usually accepts TTL level signals. This situation requires a graphics controller chip between the PIC24 and LCD modules. The graphics controller chip has digital voltage creation logic, an image buffer, and sometimes a graphic accelerator. It will have a CPU interface for the host connection and an RGB output to drive the LCD module. Usually the graphics controller chip is highly configurable and can drive a variety of LCD displays like STN, TFT, monochrome, etc. and supports a variety of timing needs. Additionally, it is possible to create a graphics controller using an FPGA or CPLD.  In this case, it will most likely use a dedicated RAM chip for the image buffer.