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Figure 23 ►

Aggregation of charge

carriers from four pixels

in bidirectional binning.

Figure 24 ►

Color processing mod-

ules of Baumer color

cameras.

4.1.9. Brightness Correction (Binning Correction)

The aggregation of charge carriers may cause an overload. To prevent this, binning cor-

rection was introduced. Here, three binning modes need to be considered separately:

Binninig

Realization

1x2

1x2 binning is performed within the sensor, binning correction also takes

place here. A possible overload is prevented by halving the exposure time.

2x1

2x1 binning takes place within the FPGA of the camera. The binning cor-

rection is realized by aggregating the charge quantities, and then halving

this sum.

2x2

2x2 binning is a combination of the above versions.

Binning 2x2

Charge quantity

4.2. Color Processing

Baumer color cameras are balanced to a color temperature of 5000 K.

Oversimplified, color processing is realized by 4 modules.

Camera

Module

The color signals r (red), g (green) and b (blue) of the sensor are amplified in total and

digitized within the camera module.

Within the Bayer processor, the raw signals r', g' and b' are amplified by using of indepen-

dent factors for each color channel. Then the missing color values are interpolated, which

results in new color values (r'', g'', b''). The luminance signal Y is also generated.

The next step is the color transformation. Here the previously generated color signals r'',

g'' and b'' are converted to the chroma signals U and V, which conform to the standard.

Afterwards theses signals are transformed into the desired output format. Thereby the

following steps are processed simultaneously:

▪

Transformation to color space RGB

▪ External color adjustment

▪

Color

adjustment as physical balance of the spectral sensitivities

In order to reduce the data rate of YUV signals, a subsampling of the chroma signals can

be carried out. Here the following items can be customized to the desired output format:

▪

Order of data output

▪

Subsampling of the chroma components to

▪

Limitation of the data rate to 8 bits

4.3. Color Adjustment – White Balance

This feature is available on all color cameras of the Baumer EXG series and takes

place within the Bayer processor.

White balance means independent adjustment of the three color channels, red,

green and blue by employing of a correction factor for each channel.

r''

Color-

Bayer

Transfor-

g''

Processor

mation

b''

White balance

or YUV

YUV 4:2:2 or YUV 4:1:1

Total charge

quantity of the

4 aggregated

pixels

Super pixel

RGB