Photon Focus MV1-D1024E, User Manual, Page: 61 / 109

4.11 Test Images
12 bit: The 10 LSB are the same as in the 10 bit mode. Bits 8 and 9 of the row number (starting
at 0) are mapped to the MSB 10 and 11. The two MSB of rows 0 to 255 have the value 0,
the two MSB of rows 256 to 511 have the value 1, and so on.
4.11.2 LFSR
The LFSR (Linear Feedback Shift Register) test image outputs a constant pattern with a
pseudo-random grey level sequence containing every possible grey level that is repeated for
every row. The LFSR test pattern was chosen because it leads to a very high data toggling rate,
which stresses the interface electronic and the cable connection.
Figure 4.49: LFSR (linear feedback shift register) test image
In the histogram you can see that the number of pixels of all grey values are the same.
Please refer to application note [AN026] for the calculation and the values of the LFSR test
image.
4.11.3 Troubleshooting using the LFSR
To control the quality of your complete imaging system enable the LFSR mode, set the camera
window to a width that is a multiple of 1024 and check the histogram. If your frame grabber
application does not provide a real-time histogram, store the image and use a graphic software
tool to display the histogram.
In the LFSR (linear feedback shift register) mode the camera generates a constant
pseudo-random 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. 4.50). On the other hand, a
non-flat histogram (Fig. 4.51) indicates problems, that may be caused either by the cable, by
the connectors or by the frame grabber.
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