Smear removal algorithm using the optical black region for CCD imaging sensors

Smearing is an inevitable phenomenon that occurs during the charge transfer process with CCD imaging sensors. For still images, smearing can be reduced by using a mechanical shutter or special drive methods, but these techniques cannot be applied to image sequences. In this paper, we propose a smear removal algorithm that can be applied to imaging systems for not only still images but also image sequences. The proposed algorithm uses the optical black region (OBR), a group of pixels located in the boundary of CCD imaging sensors. Although the OBR is not generally exposed to light, it contains smear information caused by the charge transport. For this reason, the proposed method estimates the smear component from the signal recorded in the OBR and produces a corrected OBR signal by removing noise. Then, the corrected OBR signal is uniformly subtracted from the signals in the effective pixel region to eliminate the smear effect. Moreover, the saturated pixels are substituted by the weighted average of the neighboring pixels to prevent visual degradation.