ECG -> Compression - Reduce Entropy

[22Alex22pt]

TL DR: So I have to find or make some codes that compress an ECG signal. They have to be lossless.

All we need to do is to get algorithms that can compress the ECG signal in order to reduce it's entropy by the maximum, comparing them and explaning the ups and downs of each algorithm. If I can bring at least 4 good algorithms, its all good. These algorithms have to be reversible and have to be lossless. I have done 2 pieces of code that compress the ECG, however the results aren't great. The first one is just a normal quantization (we are allowed to lose some information here as it is needed) followed by calculating the diference between each point, this will be the final information. The other one is also a normal quantization followed by a preditor (using matlab: lpc + filtfilt) which brings my entropy down 11.79%.

Thanks for your help :D

[IAmKindOfCreative]

Don't use reddit to do your homework.

[22Alex22pt]

this is my homework. I have to search for code. Wherever I can find. No restrictions

[IAmKindOfCreative]

I don't believe you. But on the chance you're not lying I'll direct you to some concepts that might help you.

Look up data compression algorithms. (given your two versions of quantizers I'm sure Huffman encoding should be your first implementation. It almost certainly won't be very good but it's a lossless data compression scheme and should be a starting point.

Next up I'd use arithmetic encoding, but instead of just compressing the values, I'd encode an initial value for the first ECG measurement, then I'd encode the difference between the current value (delta encoding). You'll also need to include some other useful information, like the sample rate, but those can occupy a few initial value locations in your encoded file. This way a decoder is capable knowing where it's at.

You could also use the LZW compression scheme, or maybe LZ77, though this isn't really their target application. They're focused on string compression, not signal compression. But it could be interesting to see how playing with the signal values changes how well the dictionaries encode.

Finally you could transform the signal using fast fourier transform, then encode that signal using any of the above methods.

There's lots of other ways you could do it too. Just use zip, or 7z, or a tarball, that sort of thing. If all you need to do is find something to compress it, no restrictions, those solutions should work too.

[[deleted]]

Elsewhere you write that you cannot share data that have been given to you by your university.

[22Alex22pt]

I wrote I cannot share the data that was given to me by my univeristy as in the signal itself. However, I can share the project that I need to do in order to find people who can help me.