The PCNN implementation and applications in image processing were discussed, For the specific implementation of PCNNs, a PCNN was forced to be a single pass network. And simplified model, look-up threshold table, and integer operation were used to decrease the time complexity. The time-index image and fingerprint time series were introduced into PCNNs, and a PCNN was combined with the traditional techniques of image processing for automatic image processing, e.g. image enhancement, edge detection, image segmentation and feature extraction, by the time-index image. The applied conditions are derived for perfect image processing, and a practical estimation of the linking coefficient is proposed, which helps to determine PCNN parameters directly.