![](http://datasheet.mmic.net.cn/280000/HMS30C7202N_datasheet_16073790/HMS30C7202N_60.png)
HMS30C7202N
2004 MagnaChip Semiconductor Ltd. All Rights Reserved. Version 1.1
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8.1.2
Color/Grayscale Dithering
Entries selected from the look-up palette are sent to the color/grayscale space/time base dither generator.
Each 4-bit value is used to select one of 15 intensity levels.
Note that two of the 16 dither values are identical. The table below assumes that a pixel data input to the LCD
panel is active HIGH. That is, a `1' in the pixel data stream will turn the pixel on, and a `0' will turn it off. If this
is not the case, the intensity order will be reversed, with "0000" being the most intense color. This polarity is
LCD panel dependent.
The gray/color intensity is controlled by turning individual pixels on and off at varying periodic rates. More
intense grays/colors are produced by making the average time that the pixel is off longer than the average
time that it is on. The proprietary dither algorithm is optimized to provide a range of intensity values that match
the eye's visual perception of color/gray gradations, with smaller changes in intensity nearer to the mid-gray
level, and greater nearer the black and the white levels. In color mode, red, green and blue components are
gray-scaled simultaneously as if they were mono pixels. The duty cycle and resultant intensity level for all 15
color/grayscale levels is summarized in Table 8-1: Color/grayscale intensities and modulation rates.
Dither Value
(4 bit value from palette)
(0% is white)
1111
100.0
1110
100.0
1101
88.9
1100
80.0
1011
73.3
1010
66.6
1001
60.0
1000
55.6
0111
50.0
0110
44.4
0101
40.0
0100
33.3
0011
26.7
0010
20.0
0001
11.1
0000
0.0
Table 8-1 LCD Colorgrayscale intensities and modulation rates
8.1.3
How to order the bit on LD[7:0] output
Intensity
Modulation Rate
(ration of ON to ON+OFF pixels)
1
1
8/9
4/5
11/15
6/9
3/5
5/9
1/2
4/9
2/5
3.9
4/15
1/5
1/9
0
In STN mode, the low order LD signals are the first pixels on the line, and the high order LD signals are later
pixels on the line.
In color mode things are different once again. LD[7] is the red component of the first pixel on the line, and
LD[6] is the green component of the pixel, and LD[5] the blue, with LD[4] being the red component of the next
pixel. This pattern continues, with LD[0] being the green component of the third pixel, and LD[7] of the next
clock being the blue component of the same pixel.