Analog Devices ADV8003 Hardware Manual page 323

scale_ycbcr_en, Encoder Map, Address 0xE487[0]
This bit is used to enable the SD luma and color scale control feature.
Function
scale_ycbcr_en
1
0 
When enabled, three 10-bit registers (SD Y scale, SD Cb scale, and SD Cr scale) control the scaling of the SD Y, Cb, and Cr output levels.
The SD Y scale register contains the scaling factor used to scale the Y level from 0.0 to 1.5 times its initial level. The SD Cb scale and SD Cr
scale registers contain the scaling factors used to scale the Cb and Cr levels from 0.0 to 2.0 times their initial levels, respectively.
The registers needed to scale the outputs are contrast[7:0],
contrast[7:0], IO Map, Address 0x1A2B[7:0]
This register is used to adjust the contrast value for Y channel. This register uses 1.7 notation.
Function
contrast[7:0]
0x00
0x80 
0xFF
cb_scale[9:0], Encoder Map, Address 0xE49E[7:0]; Address 0xE49C[3:2]
This signal is used to set the SD Cb scale value.
cr_scale[9:0], Encoder Map, Address 0xE49F[7:0]; Address 0xE49C[5:4]
This signal is used to set the SD Cr scale value.
To use this function, the values to be written to these 10-bit registers are calculated using the following equation:
Y, Cb, or Cr Scale Value = Scale Factor × 512
For example, if Scale Factor = 1.3
Y, Cb, or Cr Scale Value = 1.3 × 512 = 665.6
Y, Cb, or Cr Scale Value = 666 (rounded to the nearest integer)
Y, Cb, or Cr Scale Value = 1010 0110 10b
Reg 0xE49C, SD scale LSB register = 0x2A
Reg 0xE49D, SD Y scale register = 0xA6
Reg 0xE49E, SD Cb scale register = 0xA6
Reg 0xE49F, SD Cr scale register = 0xA6
Note: It is recommended that the SD luma scale saturation feature, saturate_luma, be enabled when scaling the Y output level to avoid
excessive Y output levels.
saturate_luma, Encoder Map, Address 0xE487[1]
This bit is used to enable the SD luma scale saturation.
Rev. B, August 2013
Description
Enabled
Disabled
cb_scale[9:0]
Description
Gain of 0
Unity gain
Gain of 2
and cr_scale[9:0].
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ADV8003 Hardware Manual