NED
NUCLi7370AT6
UME-0069-03
50
4.12 Pixel Correction
As a rule, image sensors (CCD, CMOS and so on) have fixed pattern noise and
photo response non-uniformity. Lens shading and light sources can also cause
non-uniformity. The camera is set to the optimal correction before shipping in order to
provide images of the highest grade.
The camera also has a user white correction function to cope with lens shading and
non-uniform illumination, or to be able to completely clear the uneven brightness
generated by changing the spectral response level of the light source.
Cal_wh:
Output data of each pixel in uniform illumination (digital)
Target_Val : Target value for correction (10bit digital)
Vin: Input data (digital)
Vout: Output data (digital) The corrected data is expressed in the following equation.
Vout=(Vin x Target_val) / Cal_wh
Waveform before bit correction
Output
Pixel Number
Waveform after bit correction
Output
Pixel Number
Figure 4-12-1 Waveform before and after bit correction