7-20
DS785UM1
Copyright 2007 Cirrus Logic
Raster Engine With Analog/LCD Integrated Timing and Interface
EP93xx User’s Guide
7
7
7
The values in between full on and full off are more difficult to determine and depend on the
display characteristics such as persistence, turn on time, and refresh rate. To achieve
difference in shades of gray, it is typical to have more values below the half luminance
average due to the higher sensitivity to luminance variations by the human eye at lower
levels. Other problems that occur with choosing patterns and the operating matrix parameters
are flickering (temporal distortion), walking patterns (spatial distortion), and spatial
interference patterns.
Take, for example, a 50% duty cycle. We could define the matrix as a 4Hx4Vx4F as shown in
. However, we effectively halved the refresh rate of these pixels and, depending on
the refresh rate of the display, are likely to see flickering for this shade.
Figure 7-3. Graphics Matrix for 50% Duty Cycle
To avoid flickering, it is better to play a spatial trick and turn on every other pixel so that the
eye integrates the on and off pixels between two consecutive frames. However, in the case
given in
, a spatial interference can be caused if an image displayed in this
grayscale consists of every other column activated. For this case, we would be right back to
the flickering problem shown in
. This would be true if we switched to a checker
board pattern and displayed a checker board image or almost any other pattern.
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Summary of Contents for EP93 Series
Page 28: ...P 6 DS785UM1 Copyright 2007 Cirrus Logic Preface EP93xx User s Guide PP P ...
Page 162: ...5 36 DS785UM1 Copyright 2007 Cirrus Logic System Controller EP93xx User s Guide 55 5 ...
Page 576: ...15 18 DS785UM1 Copyright 2007 Cirrus Logic UART2 EP93xx User s Guide 1515 15 ...
Page 634: ...17 38 DS785UM1 Copyright 2007 Cirrus Logic IrDA EP93xx User s Guide 1717 17 ...
Page 648: ...19 6 DS785UM1 Copyright 2007 Cirrus Logic Watchdog Timer EP93xx User s Guide 1919 19 ...
Page 688: ...21 32 DS785UM1 Copyright 2007 Cirrus Logic I2S Controller EP93xx User s Guide 2121 21 ...
Page 790: ...27 20 DS785UM1 Copyright 2007 Cirrus Logic IDE Interface EP93xx User s Guide 2727 27 ...
Page 808: ...28 18 DS785UM1 Copyright 2007 Cirrus Logic GPIO Interface EP93xx User s Guide 2828 28 ...