SED1354 Datasheet, PDF (153/472 Pages) Epson Company – Color Graphics LCD/CRT Controller

Epson Research and Development
Vancouver Design Center
Page 13
3.2.3 Memory Organization for Four Bit-per-pixel (16 Colors/Gray Shades)
Two pixels are grouped into one byte of display buffer as shown below:
Table 3-3: Pixel Storage for 4 bpp (16 Colors/Gray Shades) in One Byte of Display Buffer
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Pixel 0
Bit 3
Pixel 0
Bit 2
Pixel 0
Bit 1
Pixel 0
Bit 0
Pixel 1
Bit 3
Pixel 1
Bit 2
Pixel 1
Bit 1
Pixel 1
Bit 0
Four bit-per-pixel provides sixteen shades of gray by indexing into positions 0 through F of the
Green LUT and 16 levels of color by indexing into positions 0 through F of the Red/Green/Blue
LUTs.
3.2.4 Memory Organization for Eight Bit-per-pixel (256 Colors)
One pixel is stored in one byte of display buffer as shown below:
Table 3-4: Pixel Storage for 8 bpp (256 Colors) in One Byte of Display Buffer
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Red Bit 2
Red Bit 1
Red Bit 0
Green Bit 2 Green Bit 1 Green Bit 0 Blue Bit 1
Bit 0
Blue Bit 0
As shown above, the 256 color pixel is divided into three parts: three bits for red, three bits for green,
and two bits for blue. The red bits represent an index into the red LUT, the green bits represent an
index into the green LUT, and the blue bits represent an index into the blue LUT. Although eight bit-
per-pixel only makes sense for a color panel, this memory model can be set on a monochrome panel,
however only eight shades of gray will be visible.
Programming Notes and Examples
Issue Date: 98/10/28
SED1354
X19A-G-002-06