
4: LOOK-UP TABLE (LUT)
2-10
EPSON
S1D13806 SERIES PROGRAMMING NOTES
AND EXAMPLES (X28B-G-003-01)
The LUT address register selects which of the 256 LUT entries will be accessed. Writing to this reg-
ister will select the red bank. After three successive reads or writes to the data register (REG[1E4h])
this register is automatically incremented by one.
This register is where the 4-bit red/green/blue data is written to/read from. With each successive
read or write the internal bank select is incremented. Three successive reads from this register will
result in reading the red, then the green, and finally the blue values associated with the index set in
the LUT address register.
After the third read the LUT address register is incremented and the internal bank select points to the
red bank again.
4.2 Look-Up Table Organization
The Look-Up Table treats the value of a pixel as an index into an array of colors or gray shades.
For example, a pixel value of zero would point to the first LUT entry, whereas a pixel value of
seven would point to the eighth LUT entry.
The value contained in each LUT entry represents the intensity of the given color or gray shade.
This intensity can range in value between 0 and 0Fh.
The S1D13806 Look-Up Table is linear. This means increasing the LUT entry number results in a
lighter color or gray shade. For example, a LUT entry of 0Fh in the red bank results in bright red
output while a LUT entry of 05h results in dull red.
REG[1E2h] Look-Up Table Address Register
LUT Address
Bit 7
LUT Address
Bit 6
LUT Address
Bit 5
LUT Address
Bit 4
LUT Address
Bit 3
LUT Address
Bit 2
LUT Address
Bit 1
LUT Address
Bit 0
REG[1E4h] Look-Up Table Data Register
LUT Data
Bit 3
LUT Data
Bit 2
LUT Data
Bit 1
LUT Data
Bit 0
n/a
Table 4-1 Look-Up Table Configurations
Display Mode
4-Bit Wide Look-Up Table
Effective Gray Shades/
Colors on an Passive Panel
With Dithering Disabled
Effective Gray Shades/
Colors on a Passive Panel
With Dithering Enabled
RED
GREEN
BLUE
4 bpp gray
16
16 gray shades
8 bpp gray
16
16 gray shades
16 bpp gray
16 gray shades
64 gray shades
4 bpp color
16
16 colors
8 bpp color
256
256 colors
16 bpp color
4096 colors
65536 colors
= Indicates the Look-Up Table is not used for that display mode