Page 190
Epson Research and Development
Vancouver Design Center
13.3 Filters
When displaying computer images on a TV, several image distortions are likely to arise:
• cross-luminance distortion.
• cross-chrominance distortion.
• flickering.
These distortions are caused by the high-resolution nature of computer images which
typically contain sharp color transitions, and sharp luminance transitions (e.g., high
contrast one pixel wide lines and fonts, window edges, etc.). Three filters are available to
reduce these distortions.
13.3.1 Chrominance Filter (REG[05Bh] bit 5)
The chrominance filter adjusts the color of the TV by limiting the bandwidth of the chromi-
nance signal (reducing cross-luminance distortion). This reduces the “ragged edges” seen
at boundaries between sharp color transitions. This filter is controlled using REG[05Bh]
bit 5 and is most useful for composite video output.
13.3.2 Luminance Filter (REG[05Bh] bit 4)
The luminance filter adjusts the brightness of the TV by limiting the bandwidth of the
luminance signal (reducing cross-chrominance distortion). This reduces the “rainbow-like”
colors at boundaries between sharp luminance transitions. This filter is controlled using
REG[05Bh] bit 4 and is most useful for composite video output.
13.3.3 Anti-flicker Filter (REG[1FCh] bits [2:1])
The “flickering” effect seen on interlaced displays is caused by sharp vertical image transi-
tions that occur over one line (1 vertical pixel). For example, one pixel high lines, edges of
window boxes, etc. Flickering occurs because these high resolution lines are effectively
displayed at half the refresh frequency due to interlacing. The anti-flicker filter averages
adjacent lines on the TV display to reduce flickering. This filter is controlled using the
Display Mode register (REG[1FCh] bits [2:1]).
S1D13506
X25B-A-001-10
Hardware Functional Specification
Issue Date: 01/02/06
EPSON [ EPSON COMPANY ]
