Functions And Operations; Basic Functions; Dynamic Shading Correction - JAI CV-M 9CL Operation Manual

6. Functions and Operations

6.1. Basic functions

A 16-bit processor controls all functions in the CV-M9CL camera. The CCD sensor output is
normalized in preamplifiers. The signals are then digitized to 12 bits. Digital gain control and
look-up tables can do signal processing in 12 bits before it is truncated to a 10 or 8 bit camera
link signal.
Prism Prism
Timing Timing

6.1.1. Dynamic shading correction

The CV-M9CL camera has a digital shading correction circuit, which can compensate for prism
chromatic shading, for lens vignetting and for CCD shading. It makes the choice of lenses wider.
The camera with a given lens and a given f-number is looking on a homogeneous white scene.
A horizontal profile of the shading in 128 points is made for the 3 colors.
A vertical profile of the shading in 96 points is
made for the 3 colors.
The result is stored as gain difference from the
image centre.
Data from this h and v profile is used to adjust
the R, B and G gain depending of the H and V
position. The resulting image is then
compensated for shading caused by the lens,
prism and CCD.
The lens used is a Fujinon 15mm F2.2.
The iris is set to F5.6.
With the camera control tool it is possible to
customize the correction for a given set-up, and
store the corrections in a file. Refer to chapter 6.5.1.
Note: Lens requirements.
To obtain the best possible image, it is recommended to use lenses designed for 1/3" 3 CCD
cameras. The shading depends of the focal length and the iris setting. Avoid wide-angle lenses,
and do not use an iris setting fully open.
CV-M9 CL
A/D A/D
B B
A/D A/D
G G
A/D A/D
R R
A. gain A. gain
16 bit digital processing 16 bit digital processing
Fig. 9. Principle diagram for signal processing
Fig. 10. Shading correction.
12 bit 12 bit 12 bit 12 bit
RGB input RGB input D. Gain D. Gain
Shading Shading Shading Shading
data data map map
0 0
V V
shading shading
data data
95 95
- 8 -
Iris video Iris video
10 bit 10 bit 8/10 bit 8/10 bit
Camera Link Camera Link
CL CL
Inter Inter
face face
RGB signal RGB signal
Knee Knee
Point Point
slope slope
0 0 H shading data H shading data
CL CL
127 127