[Tracing algorithms of ECG tracks from scanned image]

This paper presents a discussion on the tracing algorithms of the extraction of Electrocardiogram (ECG) data from scanned image of hardcopy ECG. We have advanced a new algorithm integrated by seek-and-predict method and polygon model method, which can tolerate crossing of two leads, fault-line and disturbing of grid lines. Two practical situations that may be encountered while processing hardcopy ECG are discussed in detail. Furthermore, the after-treatment of extraction-filtering is considered and an SVD-based filter designed to smooth ECG signal is analyzed.