Photon Focus OEM-D1024E, User Manual

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4 Functionality
Test Image Ramp Pattern
8 bit ramp image (256 DN) 582 rows with 0 .. 255 DN, 0 .. 255 DN, 0 .. 239 DN
10 bit ramp image (1024 DN) 582 rows with 0 .. 751 DN
12 bit ramp image (4096 DN) 256 rows with 0 .. 751 DN; 256 rows with 1024 .. 1775 DN; 70
rows with 2048 .. 2799 DN
Table 4.2: Grey levels in ramp test images
Figure 4.23: Ramp test images: 8 bit output (left), 10 bit output (middle), 12 bit output (right)
LFSR
The LFSR (linear feedback shift register) test image outputs a constant pattern with a 10 bit
pseudo-random grey level sequence. In the 8 bit mode, the two LSBs are cut away.
Figure 4.24: LFSR test image
Please see [AN026] for the LFSR algorithm and the output data.
4.4.3 Troubleshooting using the LFSR
To control the quality of your complete imaging system enable the LFSR mode and check the
histogram. If your vision solution does not provide a real-time histogram, store the image and
use a graphics software to display the histogram.
In the LFSR (linear feedback shift register) mode the camera module generates a constant test
pattern containing all grey levels. If the data transmission is error free, the histogram of the
received LFSR test pattern will be flat (Fig. 4.25). On the other hand, a non-flat histogram (Fig.
4.26) indicates problems, that may be caused by the interface.
The LFSR test works only for an image width of 1024, otherwise the histogram
will not be flat.
The ramp test image should be used for the OEM-D752 camera and the resolu-
tion should be set to 512 x 512 pixels. This setup will result in a flat histogram.
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