AK8853XQ Datasheet, PDF (33/70 Pages) Asahi Kasei Microsystems – NTSC/PAL/SECAM Digital Video Decoder

[AK8853XQ/ VN]
7.21 Color killer
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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7.22 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.
7.22.1 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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Rev-E-00
33
2008/01