MT9V135C12STC Datasheet, PDF (12/17 Pages) Micron Technology – 1/4-Inch System-On-A-Chip (SOC) VGA NTSC/PAL CMOS Digital Image Sensor

Preliminary
MT9V135: SOC VGA Digital Image Sensor
Detailed Architecture Overview
Image Flow Processor
The MT9V135 IFP consists of a color processing pipeline, and a measurement and
control logic block (the camera controller). 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 signal loss caused by the lens.
Next, the data is interpolated to recover missing color components for each pixel. The
resulting interpolated RGB data passes through the current color correction matrix
(CCM), gamma, and saturation corrections, and is formatted for final output.
The measurement and control logic continuously accumulate image brightness and
color statistics. Based on these measurements, the IFP calculates updated values for
exposure time and sensor analog gains that are sent to the sensor core through the
control bus.
Black Level Conditioning
The sensor core black level calibration works to maintain black pixel values at a constant
level, independent of analog gain, reference current, voltage settings, and temperature
conditions. If this black level is above zero, it must be reduced before color processing
can begin. The black level subtraction block in the IFP re-maps the black level of the
sensor to zero prior to lens shading correction. Following lens shading correction, the
black level addition block provides capability for another black level adjustment.
However, for good contrast, this level should be set to zero.
Digital Gain
Controlled by auto exposure logic, the input digital gain stage amplifies the raw image in
low-light conditions. (Range: x1–x8).
Test Pattern
A built-in test pattern generator produces a test image stream that can be multiplexed
with the gain stage. The test pattern can be selected through register settings.
Lens Shading Correction
Inexpensive lenses tend to attenuate image intensity near the edges of pixel arrays.
Other factors also cause signal and coloration differences across the image. The net
result of all these factors is known as lens shading. Lens shading correction (LC)
compensates for these differences.
Typically, the profile of lens shading induced anomalies across the frame is different for
each color component. Lens shading correction is independently calibrated for the color
channels.
Interpolation and Aperture Correction
A demosaic engine converts the single color per pixel Bayer data from the sensor into
RGB (10-bit per color channel). The demosaic algorithm analyzes neighboring pixels to
generate a best guess for the missing color components. Edge sharpness is preserved as
much as possible.
Aperture correction sharpens the image by an adjustable amount. Sharpening can be
programmed to phase out as light levels drop to avoid amplifying noise.
PDF: 09005aef82c99cd/Source:09005aef824c99db
MT9V135_LDS_2.fm - Rev. B 3/07 EN
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