time series graph representation of EEG signals

There is a graphical representation of time series signal processing of EEG signals

What do different colors indicate?

[John D'Errico]

Huh? What graph? Was it created by some MATLAB tool? If so, then which tool? Without more information, then I might guess:

Blue indicates you are feeling blue.

Red is probably a signal of anger. It might be about how you are feeling at my response, but don't shoot the messenger.

I have a funny feeling these are all wrong, but without more information from you, it is about as much as you can expect. If you want better help, then you need to make it possible to get some help.

[sunitha]

[sunitha]

The EEG signal

[sunitha]

channels used were 8 FP1, FP2, F7,F8,PO1,PO2, O1, O2

Answer 1

[Cris LaPierre]

No way of knowing without seeing the code used to create the plots. However, the images appear to be using the default colors, so if you know what order the signals were plotted, you can figure out what each color represetns. Still, it sounds like it would be a good idea to add a legend to your plots.

There are 7 colors used in MATLAB by default to distinguish unique series. These can be determined using colororder

C = colororder

C = 7×3

0 0.4470 0.7410 0.8500 0.3250 0.0980 0.9290 0.6940 0.1250 0.4940 0.1840 0.5560 0.4660 0.6740 0.1880 0.3010 0.7450 0.9330 0.6350 0.0780 0.1840

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I'll use imagesc to show what the colors are in order (1 is first, 7 is last).

imagesc(reshape(C,7,1,3))

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So if FP1 were plotted first, it would be dark blue. If FP2 were plotted second, it would be orange. Continuing on, then O1 woud be red, and since O2 is the 8th line added to your plot, the colororder would start over, and it would also be dark blue.

[Cris LaPierre]

To specifically answer the question "What do different colors indicate?", the indicated separate data series plotted on the same axes. Think of series as the columns in your data set.

As an example, meas is a 150x4 array in the fisher-iris data set.

load fisheriris.mat
meas

meas = 150×4

5.1000 3.5000 1.4000 0.2000 4.9000 3.0000 1.4000 0.2000 4.7000 3.2000 1.3000 0.2000 4.6000 3.1000 1.5000 0.2000 5.0000 3.6000 1.4000 0.2000 5.4000 3.9000 1.7000 0.4000 4.6000 3.4000 1.4000 0.3000 5.0000 3.4000 1.5000 0.2000 4.4000 2.9000 1.4000 0.2000 4.9000 3.1000 1.5000 0.1000

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plot(meas)
legend("sepal length", "sepal width", "petal length", "petal width")

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