ov7620 OmniVision Technologies, Inc, ov7620 Datasheet - Page 9

• Manufacturer Part Number: ov7620
• Description: Single-chip Cmos Vga Color Digital Camera
• Manufacturer: OmniVision Technologies, Inc

OV7620/OV7120 Product Specifications - Rev. 1.2 (7/10/01)
The majority of signal processing is performed in the analog processing block, which does color
separation, matrixing, AGC, gamma correction, color correction, color balance, black level cali-
bration, knee smooth, aperture correction, controls for the luminance and chrominance picture
and anti-alias filtering. The analog video signals are based on the formula:
Another output data format is YCrCb, its formula is as follows:
The YCrCb /RGB Raw Data signal is fed to two 10 bit A/D converters, one for the Y/R&G chan-
nel, one is shared by Cr&Cb / B&G channels. The A/D converted data stream is further condi-
tioned in the digital formatter, finally the 16bit or 8 bit data muxing is done in the digital video port.
The on-chip 10 bit A/D can operate up to 13.5 MSPS, since it is fully synchronous to the pixel
rate, the conversion rate always follows the frame rate. An A/D black-level-calibration circuitry
ensures the black level of Y/RGB is translated to value 16, and the peak white level is limited to
240; CrCb black level is 128, Peak/Bottom is 240/16. RGB raw data output range is 16/240, 0 &
255 reserved for sync flag. Also OV7620/OV7120 support non-CCIR standard output range, that
is 1/254, 0 and 255 are reserved for sync flag.
The computation in the electronic exposure control is based on the brightness of the full image.
The exposure algorithm is optimized for normal scene which assuming the subject is well-lit rel-
ative to the background. In case of a different backlight condition, there is also a AEC White/
Black ratio selection register, which can be used as AEC algorithm adjustment to get special im-
age. Along with the AEC is the on chip AGC which can boost gain up to 24dB if needed. To
achieve proper color temperature, auto or manual white balance control is also available. There
is a separate saturation, brightness contrast and sharpness adjustment for further fine tuning of
the picture quality. OV7620/OV7120 provide a set of register to control White Balance ratio reg-
ister which can be used as increase/decrease image field Red/Blue component ratio. In most
case, the default setting may be sufficient.
The windowing feature allows the user to size the window according to their need. The window
is sizable from 4X2 to 664x492 and can be placed anywhere inside the 664X492 boundary. Not-
ed this function does not change the frame rate or data rate, it simply change the assertion of the
HREF
application for this is hardware zooming, and panning. Default output window is 640x480.
The digital video port offers 16 bit 4:2:2 format complying to the 60Hz CCIR601 timing standard.
OV7620/OV7120 also supports 8 bit data format in Cb Y Cr Y order by using port Y only and
running at twice the pixel rate while the port UV is inactive. Other than the 16 bit data bus,
OV7620/OV7120 supplies standard video timing signals such as
CHSYNC.
OV7620/OV7120 support standard ZV Port Interface Timing. It provides VSYNC, CHSYNC,
PCLK and 16 Bit data bus: Y<7:0> and UV<7:0>. PCLK rising edge clock data bus into ZV port.
Y = 0.59G + 0.31R + 0.11B; where R,G,B is the equivalent color components in each pixel
U = R-Y;
V = B-Y;
Y = 0.59G + 0.31R + 0.11B
Cr = 0.713 x (R - Y)
Cb = 0.564 X (B - Y)
to match with the horizontal and vertical region that is programmed by the user. A typical
Preliminary
Company Confidential
OMNIVISION TECHNOLOGIES INC.
VSYNC
,
HREF
,
PCLK
,
FODD,