Finding a wave graphic inside an image

Question

Hi guyz,

I need some help with a algorithm I'm working with for my college course. The idea is use an artificial neural network to read a electrocardiogram and try to recognize some disturbs in the waves, that's ok, I've the neural network and I can test it, no problem, but I'd like to give the function to the user to open a eletrocardiogram (import a jpeg) and the program find the waves and convert it in to the arrays that will feed my ANN, but there's the problem. I did some code that read the image and transform it in a binary image, but I can't find a nice way for the program to locate the waves, since the exact position can vary from hospital to hospital, I need some suggestions of approachs I should use.

Thankz!!

Answer 1

You'd have to assume a certain minimal contrast between the "signal" (the waves) and the background of the image. An edge-finding algorithm might be useful in that case. You could isolate the wave from the background and plot the wave.

This post by Rick Barraza deals with vector fields in Silverlight. You might be able to adapt the concept to your particular problem.

Answer 2

If you've got the wave values in a list, you can use a Fourier transform or FFT (fast Fourier transform) to determine the frequency content at any particular time value. Disturbances typically create additional high-frequency content (ie, sharp, steep waves) that you should be able to use to spot irregularities.