Epson S1D13705 Bit-Per-Pixel 4 Colors/Gray Shades, Bit-Per-Pixel 16 Colors/Gray Shades, Pixel Bit

Epson Research and Development	Page 13
Vancouver Design Center

3.2 2 Bit-Per-Pixel (4 Colors/Gray Shades)

2-bit pixels support four color/gray shades. In this memory format each byte of display buffer contains four adjacent pixels. Setting or resetting any pixel requires reading the entire byte, masking out the appropriate bits and, if necessary, setting bits to “1”.

Color panels derive their four colors by indexing into positions 0 through 3 of the Look-Up Table. These four LUT entries can be set to any of the 4096 possible color combinations.

Monochrome panels derive four gray shades by indexing into the first four elements of the green component of the Look-Up Table. Any of the four LUT entries can be set to any of the sixteen possible gray shades.

Bit 7	Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1	Bit 0
Pixel 0	Pixel 0	Pixel 1	Pixel 1	Pixel 2	Pixel 2	Pixel 3	Pixel 3
Bit 1	Bit 0	Bit 1	Bit 0	Bit 1	Bit 0	Bit 1	Bit 0

Figure 3-2: Pixel Storage for 2 Bpp (4 Colors/Gray Shades) in One Byte of Display Buffer

3.3 4 Bit-Per-Pixel (16 Colors/Gray Shades)

Four bit pixels support 16 color/gray shades. In this memory format each byte of display buffer contains two adjacent pixels. Setting or resetting any pixel requires reading the entire byte, masking out the upper or lower nibble (4 bits) and setting the appropriate bits to “1”.

Color panels can display up to sixteen colors simultaneously. These sixteen colors are derived by indexing into the first sixteen elements of the Look-Up Table. Each of these colors may be selected from the 4096 possible available colors.

On a monochrome panel the gray shades are generated by indexing into the first sixteen green components of the LUT. Each of these sixteen possible gray shades can be adjusted to any of the sixteen possible gray shades. For instance, one could program the first eight green LUT entries to be 0 and the second green LUT entries to be FFh. This would result in nibble values of 0 through 7 displaying as black and nibble values 8 through 0Fh displaying as white.

Bit 7	Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1	Bit 0
Pixel 0	Pixel 0	Pixel 0	Pixel 0	Pixel 1	Pixel 1	Pixel 1	Pixel 1
Bit 3	Bit 2	Bit 1	Bit 0	Bit 3	Bit 2	Bit 1	Bit 0

Figure 3-3: Pixel Storage for 4 Bpp (16 Colors/Gray Shades) in One Byte of Display Buffer

Programming Notes and Examples	S1D13705
Issue Date: 02/01/22	X27A-G-002-03