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Epson Research and Development
Page 17
Vancouver Design Center
Programming Notes and Examples S1D13505
Issue Date: 01/02/05 X23A-G-003-07
3.1.2 Memory Organization for Two Bit-Per-Pixel (4 Colors/Gray Shades)
Figure 3-2: Pixel Storage for 2 Bpp (4 Colors/Gray Shades) in One Byte of Display Buffer
In this memory format each byte of display buffer contains four adjacent pixels. Setting or
resetting any pixel will require reading the entire byte, masking out the appropriate bits and,
if necessary, setting the bits to '1'.
Two bit pixels are capable of displaying four gray shade/color combinations. For
monochrome panels the four gray shades are generated by indexing into the first four
elements of the green component of the Look-Up Table. For color panels the four colors
are derived by indexing into positions 0 through 3 of the Look-Up Table.
3.1.3 Memory Organization for Four Bit-Per-Pixel (16 Colors/Gray Shades)
Figure 3-3: Pixel Storage for 4 Bpp (16 Colors/Gray Shades) in One Byte of Display Buffer
In this memory format each byte of display buffer contains two adjacent pixels. Setting or
resetting any pixel will require reading the entire byte, masking out the upper or lower
nibble (4 bits) and setting the appropriate bits to '1'.
Four bit pixels provide 16 gray shade/color possibilities. For monochrome panels the gray
shades are generated by indexing into the first 16 elements of the green component of the
Look-Up Table. For color panels the 16 colors are derived by indexing into the first 16
positions of the Look-Up Table.
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Pixel 0
Bit 1
Pixel 0
Bit 0
Pixel 1
Bit 1
Pixel 1
Bit 0
Pixel 2
Bit 1
Pixel 2
Bit 0
Pixel 3
Bit 1
Pixel 3
Bit 0
Bit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 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