Video Adjustments; The Hue Adjust Register; The Contrast Adjust Register; The Saturation Adjust Registers - Conexant Fusion 878A Manual

Fusion 878A
PCI Video Decoder

2.5.1 The Hue Adjust Register

2.5.2 The Contrast Adjust Register

2.5.3 The Saturation Adjust Registers

2.5.4 The Brightness Register

100600B

2.5 Video Adjustments

The Fusion 878A provides programmable hue, contrast, saturation, and
brightness.
The Hue Adjust Register (HUE) is used to offset the hue of the decoded signal. In
NTSC, the hue of the video signal is defined as the phase of the subcarrier with
reference to the burst. The value programmed in this register is added to or
subtracted from the phase of the subcarrier, which effectively changes the hue of
the video. The hue can be shifted by ±90 degrees. Because of the nature of
PAL/SECAM encoding, hue adjustments can not be made when decoding
PAL/SECAM.
The Contrast Adjust Register (CONTRAST) (also called the luma gain) provides
the ability to change the contrast from approximately 0% to 200% of the original
value. The decoded luma value is multiplied by the 9-bit coefficient loaded into
this register.
The Saturation Adjust Registers (SAT_U, SAT_V) are additional color
adjustment registers. It is a multiplicative gain of the U and V signals. The value
programmed in these registers are the coefficients for the multiplication. The
saturation range is from approximately 0% to 200% of the original value.
The Brightness Register (BRIGHT) is simply an offset for the decoded luma
value. The programmed value is added to or subtracted from the original luma
value which changes the brightness of the video output. The luma output is in the
range of 0 to 255. Brightness adjustment can be made over a range of –128 to
+127.
Conexant
2.0 Functional Description
2.5 Video Adjustments
2-21