Dalsa Piranha4 Series Manual page 17

Piranha4 2K and 4K Color Camera User's Manual
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In the case of the 4k cameras, the three lines of pixels are separated by two lines of spacing and this line
spacing is equal to 2x the sensor pixel size. In the case of the 2k cameras, only a single line of space
separates the colored lines—with the exception of the monochrome line, which has three lines of spacing.
When the image passes the three lines of pixels, the red, blue and green components for the same image
location are captured at a different time as dictated by the line spacing. The camera automatically corrects
for the line spacing to ensure that the red, blue and green components of the image pixel are all aligned
when output. However, this is only correct when the object pixel size is square; i.e., the distance moved
by the object for one EXSYNC period is equal to the width of the object pixel. In some applications it may
not be possible to achieve a 'square' object pixel as fine adjustment of the lens magnification and/or the
distance moved for each EXSYNC period is not possible. This scenario may be especially apparent when
trying to integrate the camera into an existing system.
When it is not possible to generate a square object pixel, color artefacts will occur in the scan direction
and is particularly noticeable at sharp edge transitions. The size of the edge artefact is proportional to
how far the pixel is from square. To correct for this, the camera has a feature, Line Spatial Correction (or
three letter command ssa), which allows fine adjustment of the compensation mechanism the camera uses
to correct for the line spacing.
The default setting for this feature is 3 (4k model) or 2 (2k model), which is set for square object pixels.
The setting can be adjusted from 0 to 5 to compensate for rectangular pixels—whether they are too long
or to short.
The following examples of image artefacts show black to white image transitions and the associated
corrected image after applying a specific ssa setting.
Teledyne DALSA
Red
Blue
Green
Mono
Figure 10: 2K Quadlinear Sensor Line Spacing Diagram
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