44 NED
XCM
4085TLCT6
UME-0062-01
4.11 Pixel Correction
Generally speaking, image sensors (CCD, CMOS and so on) have fixed pattern
noise and photo response non-uniformity. When you use a lens, lens shadings and
light sources also can cause non-uniformity. The camera is factory set to the
optimal correction before shipping in order to provide images of high grade. The
camera also has a user white correction function in order to cope with lens shading
and non-uniform illumination.
Cal_bl : Output data of each pixel in perfect dark (factory correction)
Cal_wh : Output data of each pixel in uniform illumination (factory correction)
or when viewing a subject for correction (user white correction)
Target_Val : Target value for user correction (10bit output conversion value)
Fix_bl : Fixed value 32DN (10bit output conversion value)
Vin: Input data (Before correction) Vout :Output data (After correction)
The corrected data is expressed by the following equation.
Vout=[(Vin-Cal_bl) x (Target_val-Fix_bl) / (Cal_wh-Cal_bl)] + Fix_bl
Image “before” user arbitrary pixel is corrected. Luminance Profile of left image
Image “after” user arbitrary pixel is corrected Luminance Profile of left image
Figure 4-11-1 Waveform and image before and after bit correction
