S1D13505 Epson Electronics America, Inc., S1D13505 Datasheet - Page 172

• Manufacturer Part Number: S1D13505
• Description: LCD Controller
• Manufacturer: Epson Electronics America, Inc.

Page 18
3.1.4 Memory Organization for Eight Bit-Per-Pixel (256 Colors/16 Gray Shades)
3.1.5 Memory Organization for Fifteen Bit-Per-Pixel (32768 Colors/16 Gray Shades)
S1D13505
X23A-G-003-07
Bit 7
One Pixel
Bit 15
Reserved
Bit 7
Green Bit 2
Figure 3-5: Pixel Storage for 15 Bpp (32768 Colors/16 Gray Shades) in Two Bytes of Display Buffer
Figure 3-4: Pixel Storage for 8 Bpp (256 Colors/16 Gray Shades) in One Byte of Display Buffer
Bit 6
Bit 14
Red Bit 4
Bit 6
Green Bit 1
In eight bit-per-pixel mode each byte of display buffer represents one pixel on the display.
At this color depth the read-modify-write cycles of the lessor pixel depths are eliminated.
Each byte indexes into one of the 256 positions of the Look-Up Table. The S1D13505 LUT
supports four bits per primary color, therefore this translates into 4096 possible colors when
color mode is selected. To display the fullest dynamic range of colors will require careful
selection of the colors in the LUT indices and in the image to be displayed.
When monochrome mode is selected, the green component of the LUT is used to determine
the gray shade intensity. The green indices, with only four bits, can resolve 16 gray shades.
In this situation one might as well use four bit-per-pixel mode and conserve display buffer.
In 15 bit-per-pixel mode the S1D13505 is capable of displaying 32768 colors. The 32768
color pixel is divided into four parts: one reserved bit, five bits for red, five bits for green,
and five bits for blue. In this mode the Look-Up Table is bypassed and output goes directly
into the Frame Rate Modulator.
The full color range is only available on TFT/D-TFD or CRT displays. Passive LCD
displays are limited to using the four most significant bits from each of the red, green and
blue portions of each color. The result is 4096 (2
Should monochrome mode be chosen at this color depth, the output reverts to sending the
four most significant bits of the green LUT component to the modulator for a total of 16
possible gray shades. In this situation one might as well use four bit-per-pixel mode and
conserve display buffer.
Bit 5
Bit 13
Red Bit 3
Bit 5
Green Bit 0
Bit 4
Bit 12
Red Bit 2
Bit 4
Blue Bit 4
Bit 3
Bit 11
Red Bit 1
Bit 3
Blue Bit 3
Bit 2
Bit 10
Red Bit 0
Bit 2
Blue Bit 2
4
* 2
4
* 2
4
) possible colors.
Epson Research and Development
Programming Notes and Examples
Bit 1
Bit 9
Green Bit 4
Bit 1
Blue Bit 1
Vancouver Design Center
Issue Date: 01/02/05
Bit 0
Bit 8
Green Bit 3
Bit 0
Blue Bit 0