MT9V112 Datasheet, PDF (11/58 Pages) Micron Technology – SOC VGA DIGITAL IMAGE SENSOR

PRELIMINARY
MT9V112
SOC VGA DIGITAL IMAGE SENSOR
Architecture Overview
The MT9V112 consists of a sensor core, the color
processing pipeline, and a measurement and control
logic block (the camera controller). Below is a brief
overview of the architecture.
Sensor Core
The sensor core is taken from the MT9V012 stand-
alone sensor and includes a number of features specif-
ically targeting the mobile market. Of primary interest
is support for preview/viewfinding with hardware-
accelerated switching to full resolution for snapshots.
This switch can be achieved without adversely affect-
ing exposure or color balance. This enables taking sin-
gle frame and Xenon flash snapshots while minimizing
snapshot lag. LED snapshots are discussed below; they
also benefit significantly from this feature.
Lens Shading Correction and Black
Level Conditioning
The stream of raw data from the sensor enters the
pipeline and undergoes several transformations.
Image stream processing starts with conditioning the
black level and applying a digital gain.
The lens shading block compensates for spatially
varying signal loss caused by the lens. The block is pro-
grammable and implements separate correction func-
tions for R,G, and B independently.
Defect Correction
Following lens correction, the data stream is ana-
lyzed for the presence of defects. A two-dimensional
digital filter calculates suitable replacement values.
Edge sensitivity minimizes false detections, helping to
preserve image sharpness.
Interpolation, Aperture, and Color
Correction
The Bayer pixel pattern data is interpolated to
recover missing color components for each pixel fol-
lowing defect correction. Configurable aperture cor-
rection sharpens the image and to avoid amplifying
noise, can be programmed to be less aggressive in low
light conditions.
The resulting interpolated RGB data passes through
the current color correction matrix (CCM), gamma,
and color saturation corrections.
The CCM can be manually loaded or dynamically
configured by the auto white balance (AWB) unit. The
gamma correction unit is fully user-programmable,
and color saturation adjustments can be made both by
the user and the auto exposure unit (for dynamic satu-
ration reduction in high or low lighting situations).
Resize
The IFP can resize to virtually any output resolution
through digitally filtered sub-sampling. Output resolu-
tions include, but are not limited to, VGA, QVGA, CIF,
and QCIF. When the output resolution is smaller than
the sensor-generated image, smooth, continuous
zoom and pan become available. The user simply
defines the zoom window, pan offset, and output reso-
lution, and the resizer calculates all other parameters
for the resize function.
Camera Control
The camera controller continuously accumulates
image brightness and color statistics. Two units use
these measurements to adjust the sensor and color-
pipe settings. The auto exposure unit adjusts gain and
shutter-width to maintain a user-defined luma target.
The image measurement region can be modified to
permit, for example, back light compensation. The
user can also control the speed and sensitivity of the
algorithm from highly responsive (for LED flash and
viewfinding) to somewhat dampened (for video).
Finally, the unit can detect 50Hz or 60Hz rolling flicker
bars (due to ambient illumination) and adjusts expo-
sure appropriately to eliminate this adverse effect on
image quality.
The AWB module adjusts gains and the CCM to
compensate for the effects of changing scene illumina-
tion on the quality of the color rendition. The user has
control over the region of the scene to be analyzed as
well as the responsivity of the algorithm to illuminant
changes.
Camera Interface and Test Patterns
The MT9V112 outputs process video as a standard
ITU-R BT.656 stream, an RGB stream, or as processed
or unprocessed Bayer data. The ITU-R BT.656 stream
contains YCbCr 4:2:2 data with optional embedded
synchronization codes. This output is typically suit-
able for subsequent display by standard (progressive
scan) video equipment, or JPEG/MPEG compression.
RGB functionality provides support for LCD devices.
The MT9V112 can be configured to output 16-bit
RGB (RGB565), 15-bit RGB (RGB555), and two types of
12-bit RGB (RGB444). The user can configure internal
registers to swap odd and even bytes, chrominance
channels, and luminance and chrominance compo-
nents to ease interfacing to application processors.
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MT9V112_2.fm- Rev. A 1/05 EN
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