
S INGLE IC CMOS  COLOR AND B/W DIGIT AL CAMERAS
March 4, 2000 
Version 1.0 
4 
1.2 
Analog Processor Circuits 
1.2.1 
The image is captured by the 356 x 292 pixel image array and routed 
to the analog processing section where the majority of signal 
processing occurs. This block contains the circuitry that performs 
color separation, color correction, automatic gain control (AGC), 
gamma correction, color balance, black level calibration, “knee” 
smoothing, aperture correction, controls for picture luminance and 
chrominance, and anti-alias filtering. The analog video signals are 
based on the following formula:
Y = 0.59G + 0.31R + 0.11B 
U = R – Y 
V = B – Y 
Where R,G,B are the equivalent color components in each 
pixel.
YCrCb format is also supported, based on the formula below:
Y = 0.59G + 0.31R + 0.11B 
Cr = 0.713 (R – Y) 
Cb = 0.564 (B – Y) 
The YCrCb/RGB data signal from the analog processing section is 
fed to two on-chip 8-bit analog-to-digital (A/D) converters: one for 
the Y/RG channel and one shared by the CrCb/BG channels. The 
converted data stream is further conditioned in the digital formatter. 
The processed signal is delivered to the digital video port through the 
video multiplexer which routes the user-selected 16-, 8-, or 4-bit 
video data to the correct output pins. 
The on-chip 8-bit A/D operates up to 9 MHz, and fully synchronous 
to the pixel rate. Actual conversion rate is related to the frame rate. 
A/D black-level calibration circuitry ensures: 
Overview 
 
The black level of Y/RGB is normalized to a value of 16 
 
The peak white level is limited to 240 
 
CrCb black level is 128 
 
CrCb Peak/bottom is 240/16 
 
RGB raw data output range is 16/240 
 (Note: Values 0 and 255 are reserved for sync flag)
1.2.2 
The algorithm used for the electronic exposure control is based on the 
brightness of the full image. The exposure is optimized for a “normal” 
scene that assumes the subject is well lit relative to the background. In 
situations where the image is not well lit, the automatic exposure 
control (AEC) white/black ratio may be adjusted to suit the needs of 
the application.
Additional on-chip functions include 
 
AGC that provides a gain boost of up to 24dB
Image Processing
 
White balance control that enables setting of proper color 
temperature and can be programmed for automatic or manual 
operation.
 
Separate saturation, brightness, contrast, and sharpness 
adjustments allow for further fine-tuning of the picture quality 
and characteristics.
The OV6630 image sensor also provides control over the White 
Balance ratio for increasing/decreasing the image field Red/Blue 
component ratio. The sensor provides a default setting that may be 
sufficient for many applications. 
1.2.3 
The windowing feature of the OV6630/OV6130 image sensors allows 
user-definable window sizing as required by the application. Window 
size setting (in pixels) ranges from 2 x 2 to 356 x 292, and can be 
positioned anywhere inside the 356 x 292 boundary. Note that 
modifying window size and/or position does not change frame or data 
rate. The OV6630/OV6130 imager alters the assertion of the HREF 
signal to be consistent with the programmed horizontal and vertical 
region. The default output window is 352 x 288.
Windowing 
1.2.4 
The OV6630/OV6130 image sensor includes a Zoom Video (ZV) 
function that supports standard ZV Port interface timing. Signals 
available include VSYNC, CHSYNC, PCLK and 16-bit data bus: 
Y[7:0] and UV[7:0]. The rising edge of PCLK clocks data into the ZV 
port. See Figure 3. Zoom Video Port Timing below. 
Zoom Video Port (ZV)