AK8854VQ Datasheet, PDF (54/95 Pages) Asahi Kasei Microsystems – Multi-Format Digital Video Decoder

[AK8854VQ]
7.22 Color killer
In CVBS or S-video input, the chroma signal quality of the input signal is determined by comparison of its
color burst level against the threshold setting in the color killer control register. If the level is below the
threshold, the color killer is activated, resulting in processing of the input as a monochrome signal and
thus with CbCr data fixed at 0x80. Depending on the register setting, the color killer may also be
activated by failure of the color decode PLL lock.
COLKILL-bit: Settings for color killer ON and OFF
COLKILL-bit
[0]
Enable
[1]
Disable
Notes
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CKLVL[3:0]-bits: For threshold setting; default setting [1000] = −23dB.
CKSCM[1:0]-bits: Used for threshold setting with SECAM input; expands 2-bit for CKLVL[3:0]-bit
CKILSEL: Settings for color killer activation
CKILSEL-bit
Condition for activation
[0]
Burst level below threshold setting in CKLVL[3:0]-bits
[1]
Burst level below threshold setting in CKLVL[3:0]-bits, or
Failure of color decode PLL lock
Notes
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7.23 Image quality adjustments
Image quality adjustments consist of contrast, brightness, sharpness, color saturation, and hue
adjustment. All image quality adjustments are disabled during the vertical blanking interval, but contrast
and brightness adjustment can be enabled by the register setting.
7.23.1 Contrast adjustment
CONT[7:0]-bits: For contrast adjustment; default value 0x80 (no adjustment)
Contrast adjustment involves multiplication by the gain factor setting in this register. The equation
of the multiplication can be modified by register setting as follows.
If CONTSEL = [0], then YOUT = (CONT/128) x (YIN – 128) + 128
If CONTSEL = [1], then YOUT = (CONT/128) x YIN
YOUT: Contrast obtained by the calculation
YIN: Contrast before the calculation
CONT: Contrast gain factor (register setting value)
The gain factor can be set in the range 0~255. If the calculated value is outside the specified
contrast range, it is clipped to the upper ‘254’ or lower ‘1’ limit. With a control bit 601LIMIT setting of
[1], the output will be in the range 16~235.
CONTSEL-bit: Settings for contrast adjustment Inclination
CONTSEL -bit
Inclination
[0]
Toward luminance of 128
[1]
Toward luminance of 0
Notes
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MS0973-E-01
54
2008/07