Test Images - Photon Focus MV2-D1280-640 User Manual

User-defined Look-up Table
In the 'User' mode, the mapping of input to output grey levels can be configured arbitrarily by
the user. There is an example file in the PFRemote folder.
Figure 4.10: Data path through LUT

4.3.3 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 of 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 for an image
resolution of <w> x 1024, where <w> must be a multiple of 256 (e.g. full resolution of
1280x1024).
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.
Test images give the correct result only at a resolution of <w> x 1024, where <w>
must be a multiple of 256 (e.g. full resolution of 1280x1024).
Ramp
The ramp test image outputs a constant pattern with increasing grey level from the left to the
right side (see Fig. 4.11).
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.
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.
Troubleshooting using the LFSR
To check the quality of your complete imaging system enable the LFSR mode and check the
histogram. If your frame grabber application does not provide a real-time histogram, store the
image and use graphics software to display the histogram.
4.3 Pixel Response
U s e r L U T
y = f ( x )
1 0 b i t
8 b i t
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