Photon Focus MV-D1024E-3D01-160, Руководство пользователя

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4 Functionality
How to Obtain a Grey Reference Image
In order to improve the image quality, the grey reference image must meet certain demands.
• The grey reference image must be obtained at uniform illumination.
Use a high quality light source that delivers uniform illumination. Standard illu-
mination will not be appropriate.
• When looking at the histogram of the grey reference image, ideally there are no grey
levels at full scale (4095 DN @ 12 bit). All pixels that are saturated white will not be
properly corrected (see Fig. 4.29).
• Camera settings such as exposure time, LinLog, skimming and digital gain may influence
the grey level. Therefore, the camera settings of the grey reference image must be
identical with the camera settings of the corrected image.
2400 2600 2800 3000 3200 3400 3600 3800 4000 4200
0
0.2
0.4
0.6
0.8
1
Histogram of the uncorrected grey reference image
Grey level, 12 Bit [DN]
Relative number of pixels [−]
grey reference image ok
grey reference image too bright
Figure 4.29: Proper grey reference image for gain correction
4.4.4 Corrected Image
Offset, gain and hot pixel correction can be switched on seperately. The following
configurations are possible:
• No correction
• Offset correction only
• Offset and hot pixel correction
• Hot pixel correction only
• Offset and gain correction
• Offset, gain and hot pixel correction
In addition, the black reference image and grey reference image that are currently stored in
the camera RAM can be output.
Table 4.2 shows the maximum values of the correction matrices, i.e. the error range that the
offset and gain algorithm can correct.
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