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PRELIMINARY
1M28, 1M75, and 1M150 User’s Manual
03-32-00525-04
DALSA
Sensor Cosmetics: Blemishes Types
The 1MXXX one megapixel CMOS sensors have two different blemish types, referred to as hot
pixels (bright blemishes) and dark blemishes.
Hot Pixels
Hot pixels are pixels that generate excessive amounts of dark current relative to other pixels. Some
hot pixels will generate dark current at 10 to 20 times the rate of a normal pixel. Hot pixels are
isolated single pixel defects. They follow the general rule of thumb for dark current where the dark
current doubles every 7-8°C. They are more easily recognizable when the camera is in dark
conditions.
Figure 1: Typical Output at Dark, 1ms Exposure Time
Figure 1 depicts the number of pixels that generate larger amounts of dark current than your
average pixel—the average pixel level output is 7DN.
Figure 2: Typical Output at Dark, 10ms Exposure Time
Figure 2 depicts the number of pixels that generate larger amounts of dark current than your
average pixel—the average pixel level output is 8DN.
