[Eeglablist] Exporting continuous EEG data from BESA to EEGLAB

Arnaud Delorme arno at ucsd.edu
Wed Sep 14 00:48:40 PDT 2011


Dear Chang,

do you think one reason why the EDF files look different in EEGLAB could be that EDF is 16-bit and that your data is probably 18+ bits?
There are 2 functions to import EDF in EEGLAB (2 plugins), did you try the other one? When you reimport the EDF file in BESA you have exported in BESA, does it look different as well or is it just in EEGLAB. We do not have BESA so it is hard for us to track down that issue. I feel pretty confident about the BIOSIG function, although it is true that we have been arguing a couple of years ago with the author of the function about minor signal calibration issues.

Best,

Arno

On Aug 25, 2011, at 1:22 AM, Chang Gu wrote:

> Hi all,
> 
> I'm trying to transfer data between EEGlab and BESA for eye blink correction and artifact rejection. But when we exported the EEG data from Besa in simple binary format (.dat file) and read it by EEGlab using 'Import data:  FromASCII/float file or Matlab array', the potential value of the data was rounded and we lost the decimal parts (e.g 80. 232 changed to 80). I also tried to have BESA export data in ascii format, but still only have integer part. I suspect that BESA rounds the Continuous data automatically to the integer (since I use Matlab fread() read the .dat, but only see the integers.)
> 
> Another option is to export the data as .edf file and use biosig plugin in EEGLAB to read it. 
> The .edf from BESA preserves the decimal part, but the value changed somehow in EEGLAB... I'm not sure if the plugin works correctly or not... (Someone looks into this function and compared the results?)  
> 
> Does anyone know how to export (continuous) data from BESA to EEGLAB without losing resolution? 
> 
> Thanks!
> 
> Chang  
> 
> -- 
> Chang Gu
> Psychology & Human Development
> Vanderbilt University 
> Nashville, TN
> 
> 
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