NED
UME-0034-03
XCM8060SA_8040SA_6040SA
49
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_bl: Output data of each pixel at perfectly dark (digital)
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-Cal_bl) x Target_val /
(Cal_wh-Cal_bl)
Waveform before bit correction
Output
Pixel Number
Waveform after bit correction
Output
Pixel Number
Figure 4-12-1 Waveform before and after bit correction
