Samsung S3C2440A - Manual (Page 374)

LCD CONTROLLER S3C2440A RISC MICROPROCESSOR
15-6
256 Level Color Mode Operation
The S3C2440A LCD controller can support an 8-bit per pixel 256 color display mode. The color display mode can
generate 256 levels of color using the dithering algorithm and FRC. The 8-bit per pixel are encoded into 3-bits for
red, 3-bits for green, and 2-bits for blue. The color display mode uses separate lookup tables for red, green, and
blue. Each lookup table uses the REDVAL[31:0] of REDLUT register, GREENVAL[31:0] of GREENLUT register,
and BLUEVAL[15:0] of BLUELUT register as the programmable lookup table entries.
Similar to the gray level display, 8 group or field of 4 bits in the REDLUR register, i.e., REDVAL[31:28],
REDLUT[27:24], REDLUT[23:20], REDLUT[19:16], REDLUT[15:12], REDLUT[11:8], REDLUT[7:4], and
REDLUT[3:0], are assigned to each red level. The possible combination of 4 bits (each field) is 16, and each red
level should be assigned to one level among possible 16 cases. In other words, the user can select the suitable
red level by using this type of lookup table. For green color, the GREENVAL[31:0] of the GREENLUT register is
assigned as the lookup table, as was done in the case of red color. Similarly, the BLUEVAL[15:0] of the BLUELUT
register is also assigned as a lookup table. For blue color, 2 bits are allocated for 4 blue levels, different from the 8
red or green levels.
4096 Level Color Mode Operation
The S3C2440A LCD controller can support a 12-bit per pixel 4096 color display mode. The color display mode can
generate 4096 levels of color using the dithering algorithm and FRC. The 12-bit per pixel are encoded into 4-bits
for red, 4-bits for green, and 4-bits for blue. The 4096 color display mode does not use lookup tables.