ASX340AT_16 Datasheet, PDF (16/54 Pages) ON Semiconductor – 1/4‐inch Color CMOS NTSC/PAL Digital Image SOC

ASX340AT
300
250
200
150
100
50
0
0
Gamma Correction
0.45
1000
2000
3000
Input RGB, 12-bit
4000
Figure 11. Gamma Correction Curve
RGB to YUV Conversion
For further processing, the data is converted from RGB
color space to YUV color space.
Color Kill
To remove high-or low-light color artifacts, a color kill
circuit is included. It affects only pixels whose luminance
exceeds a certain preprogrammed threshold. The U and V
values of those pixels are attenuated proportionally to the
difference between their luminance and the threshold.
YUV-to-RGB/YUV Conversion and Output Formatting
The YUV data stream emerging from the colorpipe can
either exit the color pipeline as-is or be converted before exit
to an alternative YUV or RGB data format.
Output Format and Timing
YUV/RGB Data Ordering
The ASX340AT supports swapping YCbCr mode, as
illustrated in Table 10.
YUV Color Filter
As an optional processing step, noise suppression by
one-dimensional low-pass filtering of Y and/or UV signals
is possible. A 3- or 5-tap filter can be selected for each signal.
TABLE 10. YCbCr OUTPUT DATA ORDERING
Mode
Data Sequence
Default (no swap)
Cb_i
Y_i
Cr_i
Y_i+1
Swapped CbCr
Cr_i
Y_i
Cb_i
Y_i+1
Swapped YC
Y_i
Cb_i
Y_i+1
Cr_i
Swapped CbCr, YC
Y_i
Cr_i
Y_i+1
Cb_i
TABLE 11. RGB ORDERING IN DEFAULT MODE
Mode (Swap Disabled)
565RGB
555RGB
444 x RGB
x444RGB
Byte
Odd
Even
Odd
Even
Odd
Even
Odd
Even
D₇D₆D₅D₄D₃D₂D₁D₀
R₇R₆R₅R₄R₃G₇G₆G₅
G₄G₃G₂B₇B₆B₅B₄B₃
0 R₇R₆R₅R₄R₃G₇G₆
G₅G₄G₃B₇B₆B₅B₄B₃
R₇R₆R₅R₄G₇G₆G₅G₄
B₇B₆B₅B₄ 0 0 0 0
0 0 0 0 R₇R₆R₅R₄
G₇G₆G₅G₄B₇B₆B₅B₄
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