HD66781 Datasheet, PDF (102/196 Pages) Renesas Technology Corp – 720-channel Source Driver for a-Si TFT/Low Temperature Poly-Si TFT Panels with 262,144-color display RAM

HD66781
Preliminary
OSD and α blending functions
The HD66781 incorporates OSD and α blending functions. The OSD image data has 3 α bits to select
transmission rates among 0, 25, 50, 75, 100%. The HD66781 not only handles 32,678-color OSD at
maximum but also enables picture display data as OSD, in addition to usual single color text display. The
HD66781 realizes various ways of display with a single-chip configuration.
The HD66781 eliminates the processing of OSD and α blending from the microcomputer. Just transmitting
OSD image data including α bits into the LCD driver as usual enables OSD and α blending display.
OSD and α blending processing
The HD66781 writes data to RAM as an OSD image according to the setting of OSD bit. An image read
out as OSD according to the OSD image display setting is displayed after being processed according to the
transmission rate set by α bits. OSD and α blending settings can be made by pixels (RGB).
Table 55
α2 α1 α0 Transmission Picture processing (Display data)
rate
Picture processing (Display data)
0 0 0 0%
Base image display
Base image x 1.0 + OSD image x 0
001
-
Setting disabled
-
0 1 0 25%
Base image (75%) + OSD image
(25%) display
25% transmission
0 1 1 75%
Base image (25%) + OSD image
(75%) display
75% transmission
1 0 0 50%
Base image (50%) + OSD image
(50%) display
Base image x 0.5 + OSD image x 0.5
101
-
Setting disabled
-
1 1 0 100%
OSD image display
Base image x 0 + OSD image x 1.0
111
-
Setting disabled
-
Note 1) The OSD image is displayed 100% when base image is turned off (BASEE = 0).
Rev.0.5, July.31.2003, page 102 of 196