SD1200 Datasheet, PDF (18/35 Pages) List of Unclassifed Manufacturers – Analog-Interface XGA/SXGA TFT LCD Display Controller

SmartASIC, Inc.
SD1200
PRELIMINARY DATA SHEET
3.2.
Buffer memory and read/write control block
The SD1200 uses internal buffer memory to store a portion of the input image for
image scaling and output synchronization. No external memory buffer is needed for
the SD1200. The write control logic ensures the input data are stored into the right
area of the buffer memory, and the read control logic is responsible to fetch the data
from the buffer memory from the correct area and at the correct timing sequence.
With the precise timing control of the write and read logic, the output image is
appropriately scaled to the full screen, and the output signal is perfectly synchronized
with the input signals.
3.3. Image scaling, interpolation and dithering block
The SD1200 supports both automatic image scaling and interpolation.
3.3.1.
Image scaling
The SD1200 supports several different input modes, and the input image may have
different sizes. It is essential to support automatic image scaling so that the input
image is always displayed to the full screen regardless the input mode. The SD1200
scale the images in both horizontal and vertical directions. It calculates the correct
scaling ratio for both directions based upon the LCD panel resolution, and the input
mode and timing information produced by the “Input mode detection & auto
calibration” block. The scaling ratio is re-adjusted whenever a different input mode is
detected. The ratio is then fed to the buffer memory read control logic to fetch the
image data with the right sequence and timing. Some of the image data may be read
more than once to achieve scaling effect.
3.3.2.
Image interpolation
The SD1200 supports image interpolation to achieve better image quality. A basic
image scaling algorithm replicates the input images to achieve the scaling effect. The
replication scheme usually results in a poor image quality. The SD1200 implements
both linear interpolation and a proprietary interpolation algorithm. Through external
micro-controller, users can chose among different interpolation algorithm.
September, 1998
SmartASIC Confidential
18