Abstract
Watermarking is currently investigated as an efficient and safe method of embedding additional patient or environment-related data into the electrocardiogram. This paper presents experimental work on the assessment of the loss of ECG (electrocardiogram signal) diagnostic quality from the industrial standard EN60601-2-25:2015 point of view. We implemented an original time-frequency watermarking technique with an adaptive beat-to-beat lead-independent data container design. We tested six wavelets, six coding bit depth values (including the automatic noise-dependent one) and two types of watermark content to find the conditions that are necessary for watermarked ECG to maintain the compliance with International Electrotechnical Commission (IEC) requirements for interpretation performance. Unlike other authors, we did not assess the differences of signal values, but errors in ECG wave delineation results. The results of a total of 7300 original and watermarked 10 s ECGs were statistically processed to reveal possible interpretation quality degradation due to watermarking. Finally we found (1) the Symlet of 11-th order as the best of the wavelets that were tested; (2) the important role of ECG wave delineation and noise tracking procedures; (3) the high influence of the watermark-to-noise similarity of amplitude and values distribution and (4) the stability of the watermarking capacity for different heart rates in atrial rhythms.
Highlights
Digital watermarking is a data processing method that is aimed at hiding auxiliary information in a data carrier according to steganography rules [1]
An example case of difference between decompositions with db5 and db10 wavelets is presented in Figure 5, similar results were recorded for all other cases
The paper presents an original concept of wavelet-based irreversible watermarking of electrocardiogram signal (ECG) based on expected variations of local bandwidth related to P, QRS and T wave positions
Summary
Digital watermarking is a data processing method that is aimed at hiding auxiliary information in a data carrier according to steganography rules [1]. The watermarking technique was originally proposed for images, recently various data types have been reported as hosts for embedded data. No assumptions are made about the secret ( called the watermark or embedded data) and the carrier ( known as the host or cover signal). Usage of watermarking for medical images and signals offers embedding of sensitive patient data into the record and prevents accidental confusion of the link between signal and identity. The original meaning of making the secret ‘invisible’ is interpreted here as: the medical content of the carrier should not be altered by the watermarking process
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call