HD49815TF Datasheet, PDF (17/25 Pages) Hitachi Semiconductor – Digital Camera Signal Processor

HD49815TF
c. Luminance correction
The ratio of the red and blue levels changes according to the color temperature of the imaged object.
For example, if a red object is imaged at a low color temperature, the luminance level increases and
the object appears to have a lower chrominance. Therefore, the luminance correction circuit
performs luminance-correction processing to implement color depth reproduction.
The luminance-correction circuit is set in State Data SP_A5 [12, 13].
d. Y setup
Since the OB clamp processes the signal, the black level of the 10-bit signal input to the
HD49815TF is fixed to 48/1024. The Y-setup circuit subtracts 48 at the black level. However,
when 48 at the black level differs due to the noise mixed in the analog signal, the Y-setup circuit
subtracts that value.
The Y-setup circuit is set in State Data SP_A5 [6].
e. Gamma correction
The gamma-correction circuit implements the gamma-correction processing for the separated Y
signal. Four kinds of values can be set independently, according to the input-signal level, to acquire
optimal gamma characteristics: the gamma input limit, the gamma knee coefficient, the gamma
coefficient, and the gamma black clipping.
The gamma correction circuit is set in State Data SP_A5 [1 to 4].
f. Highlight enhancer
For input-Y signal levels in excess of 100 IRE, the highlight enhancer implements highlight
enhancer processing.
This circuit is set in State Data SP_A5 [0, 5, and 14].
g. Fade
The fade circuit amplifies the luminance signal by a factor of 0 to 1.
This circuit is set in State Data SP_A5 [9].
4. Zoom, encode block, TG, SSG, and AWB and AE detection blocks
a. Zoom processing
The Y, R-Y, and B-Y signals completed the color-signal processing and the luminance-signal
processing can be electronically zoomed by a factor of 1 to 256.
After clipping CCD signals for V direction, zoom circuit clips these signals for H direction, and
expand these signals for H and V directions.
The zooming times and the read starting position for the V and H directions are set in State Data
TM_A2 [3, 4, 5, 6, 8, and 9] and ZM_A0 to 6.
b. Encode block
This circuit encodes the signals completed the color-signal processing, the luminance-signal
processing, and the zoom processing as the NTSC/PAL TV-monitor method.
A DAC that converts the digital signal to an analog signal is provided. The DAC has two channels:
one for R-Y signals and one for B-Y signals.
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