NEC µPD72257 Preliminary User's Manual page 153

Video Input (Ravin-M only)
VInR[5:0]ITUn[5:0]
VInG[1:0]ITUn[7:6]
VInG[5:2]
VInB[5:0]
VInSYNC1
VInSYNC2
VInCLK
Figure 6-1
Video Input data
formats
YUV adjustment
RGB(888) conversion
Scale and crop
Dithering
YUV(4:2:2)
YUV(4:2:2)
Data control
Sync extraction
RGB(666)
RGB(666)
RGB(888)
RGB(888)
Scale
and
crop
VI0FFOINT
Video Input module block diagram
The Video Input accepts following data formats:
• RGB(666)/RGB(565) data with composite (CSYNC) or separate
(HSYNC and VSYNC) synchronization signal input
• ITU-R656 conform YUV(4:2:2) data with synchronization via
embedded synchronization bytes
In case of ITU-R656 video input data the YUV(4:2:2) data is converted to YUV
(4:4:4) format and can then be adjusted in order to optimized brightness, contrast
and colour saturation. If monochrome images are captured, the colour can be
changed by replacing U and V by predefined values.
All further data video data processing is applied to 24-bit RGB(888) data, i.e. YUV
(4:4:4) and RGB(565)/RGB(666) is converted to RGB(888).
The RGB(888) video data is passed to a scaling and cropping unit, that allows to
resize the image in x- and y-direction independently.
In order to reduce visible luminance steps of 16-bit colour format RGB(565), that
is finally stored in the framebuffer, the dither unit adds some small random noise
to the internal 24-bit colour format RGB(888) before reducing to 16-bit output
format – effectively this hides the luminance steps to the human eye. The amount
of noise to add, thus the strength of the luminance steps covering, can be adjusted
by a register value.
The output data format of the dithering unit is 16-bit RGB(565).
Preliminary User's Manual S19203EE1V3UM00
YUV
YUV(4:4:4)
adjustment
YUV(4:4:4)
YUV(4:4:4)
YUV(4:4:4)
RGB(888)
32 bit
Dithering
RGB(888) RGB(565)
VI0AHEINT
Chapter 6
32 bit
FIFO
VI0SCLINT
APB
AHB
153