OV6630 datasheet(4/29 Pages) ETC

4 / 29 page

SINGLE IC CMOS COLOR AND B/W DIGITAL CAMERAS

March 4, 2000

Version 1.0

1.2

Analog Processor Circuits

1.2.1

Overview

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:

⇒ 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

Image Processing

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

⇒ 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

Windowing

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.

1.2.4

Zoom Video Port (ZV)

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.

OV6630 Datasheet(PDF) 4 Page - List of Unclassifed Manufacturers

OV6630 Datasheet(HTML) 4 Page - List of Unclassifed Manufacturers

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Datasheet Download

Link URL