SD1210 Datasheet, PDF (17/46 Pages) List of Unclassifed Manufacturers – Dual-Interface SXGA TFT LCD Display Controller

SmartASIC, Inc.
SD1210
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 SD1210 supports both automatic image scaling and interpolation.
3.3.1.
Image scaling
The SD1210 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 SD1210
scales 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 the scaling effect.
3.3.2.
Image interpolation
The SD1210 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 SD1210 implements a
proprietary interpolation algorithm to improve the image quality. The programmable
interpolation is implemented with a 256-entry mapping table in the EEPROM to allow
system users to adjust the bi-linear interpolation parameters to control the sharpness
and smoothness quality of the image. In the default setting, the mapping table
contains a straight line of slope equal to 1, i.e. the data in entry N equal to the value
N. If the mapping table contains a line of slope equal to 2, then the output image will
be a bit sharper than the image generated by a table with the default setting. Through
an external microcontroller, users can chose among different interpolation algorithm.
3.3.3.
Dithering
The SD1210 supports 16.7 million true colors for a 6-bit panel. Two dithering
algorithms are implemented and users can chose between them through the external
microcontroller. The first one is area-based dithering, and the second one is a frame-
based frame modulation, which also is called frame rate control. Through the external
microcontroller, users can choose among different dithering algorithms.
November, 1999
SmartASIC Confidential
17
Revision B