HD66781 Datasheet, PDF (106/196 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
Resizing setting
The HD66781 selects resizing (contraction) rate according to the setting of RSR bit. Specify the RAM
window-address range to fit into the resized picture. If resizing creates surplus pixels according to the
result of calculation using the following formulas, set them in RCV, RCH registers before writing data to
RAM.
X
Original
Y
image
data size
HD66781
GRAM Address
(X0,Y0)
Rx
RAM write
Ry
data
(1/N resizing)
(X0+Rx-1,Y0+Ry-1)
Formulas for calculating the number of surplus pixels
The number of surplus pixels in horizontal direction
L = X mod N
The number of surplus pixels in vertical direction
M = Y mod N
Resized picture size in horizontal direction
Rx = (X-L)/N
Resized picture size in vertical direction
Ry = (Y-M)/N
Resizing Setting, surplus pixel calculation
Table 57
Original image (before resizing)
number of data in horizontal direction
X
number of data in vertical direction
Y
resizing ratio
1/N
HD66781 settings
Resizing setting
number of data in horizontal direction
number of data in vertical direction
RAM writing start address
RAM window address
RSR
RCV
RCH
AD
HSA
HEA
VSA
VEA
N-1
L
M
(X0, Y0)
X0
X0+Rx - 1
Y0
Y0+Ry - 1
X=240
Y=320
Original
image data
240 x 320
(0,0)
HD66781
GRAM address
Rx=120
Ry=160
RAM write
data
(1/2 resizing)
120 x 160
(119,159)
Resizing setting example (1/2 size)
Rev.0.5, July.31.2003, page 106 of 196