mt9v125 aptina, mt9v125 Datasheet - Page 12

• Manufacturer Part Number: mt9v125
• Description: 1/4-inch System-on-a-chip Soc Vga Ntsc And Pal Cmos Digital Image Sensor
• Manufacturer: aptina

Image Flow Processor
Black Level Conditioning
Digital Gain
Test Pattern
Lens Shading Correction
Interpolation and Aperture Correction
PDF: 09005aef829db8a0/Source: 09005aef829dbfdb
MT9V125_LDS_2.fm - Rev. A 4/07 EN
The MT9V125 IFP consists of a color processing pipeline, and a measurement and con-
trol 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) as well as the gamma and saturation corrections, and is formatted for final out-
put.
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 con-
trol bus.
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 sen-
sor 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.
Controlled by auto exposure logic, the input digital gain stage amplifies the raw image in
low-light conditions (range: x1–x8).
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.
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) com-
pensates for these differences.
Typically, the profile of lens-shading-induced anomalies across the frame is different for
each color component. Therefore, lens shading correction is independently calibrated
for the color channels.
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. To avoid amplifying
noise, sharpening can be programmed to phase out as light levels drop.
MT9V125: 1/4-Inch VGA SOC Digital Image Sensor
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Detailed Architecture Overview
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