Datasheet

Functional Description
Version 1.6, February 28, 2006 Proprietary to OmniVision Technologies 3
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Image Sensor Array
The OV2640 sensor has an image array of 1632 columns
by 1232 rows (2,010,624 pixels). Figure 3 shows a
cross-section of the image sensor array.
Figure 3 Sensor Array Region Color Filter Layout
The color filters are arranged in a Bayer pattern. The
primary color BG/GR array is arranged in line-alternating
fashion. Of the 2,010,624 pixels, 1,991,040 (1632x1220)
are active. The other pixels are used for black level
calibration and interpolation.
The sensor array design is based on a field integration
read-out system with line-by-line transfer and an
electronic shutter with a synchronous pixel read-out
scheme.
Analog Amplifier
When the column sample/hold circuit has sampled one
row of pixels, the pixel data will shift out one-by-one into
an analog amplifier.
Gain Control
The amplifier gain can either be programmed by the user
or controlled by the internal automatic gain control circuit
(AGC).
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0 1 2 3 4 5
1626 1627 1628 1629 1630 1631
Column
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Optical
Black
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1220
Active
Lines
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10-Bit A/D Converters
After the analog amplifier, the bayer pattern Raw signal is
fed to two 10-bit analog-to-digital (A/D) converters, one for
G channel and one shared by the BR channels. These
A/D converters operate at speeds up to 20 MHz and are
fully synchronous to the pixel rate (actual conversion rate
is related to the frame rate).
Channel Balance
The amplified signals are then balanced with a channel
balance block. In this block, the Red/Blue channel gain is
increased or decreased to match Green channel
luminance level.
Balance Control
Channel Balance can be done manually by the user or by
the internal automatic white balance (AWB) controller.
Black Level Compensation
After the pixel data has been digitized, black level
calibration can be applied before the data is output. The
black level calibration block subtracts the average signal
level of optical black pixels to compensate for the dark
current in the pixel output. The user can disable black
level calibration.
Windowing
The OV2640 allows the user to define window size or
region of interest (ROI), as required by the application.
Window size setting (in pixels) ranges from 2 x 4 to
1632 x 1220 (UXGA) or 2 x 2 to 818 x 610 (SVGA), and
408 x 304 (CIF), and can be anywhere inside the
1632 x 1220 boundary. Note that modifying window size
or window position does not alter the frame or pixel rate.
The windowing control merely alters the assertion of the
HREF signal to be consistent with the programmed
horizontal and vertical ROI. The default window size is
1600 x 1200. Refer to Figure 4 and registers HREFST,
HREFEND, REG32, VSTRT, VEND, and COM1 for
details.