Test Images; Ramp; Lfsr - Photon Focus CameraLink MV1-D1312 series User Manual

4 Functionality
Typical LinLog2 Response Curve − Varying Parameter Time2
300
250
200
150
100
50
0
Figure 4.14: Response curve for different LinLog settings in LinLog3 mode

4.3 Test Images

Test images are generated in the camera FPGA, independent of the image sensor. They can be
used to check the transmission path from the camera to the frame grabber. Independent from
the configured grey level resolution, every possible grey level appears the same number of
times in a test image. Therefore, the histogram of the received image must be flat.
A test image is a useful tool to find data transmission errors that are caused most
often by a defective cable between camera and frame grabber.
The analysis of the test images with a histogram tool gives the correct result at
full resolution only.

4.3.1 Ramp

Depending on the configured grey level resolution, the ramp test image outputs a constant
pattern with increasing grey level from the left to the right side (see Fig. 4.15).

4.3.2 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.
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.
28
Time1=850, Value1=19, Value2=18
Illumination Intensity
T2 = 950
T2 = 960
T2 = 970
T2 = 980
T2 = 990