Psignifit on Win64

Today I wanted to try Psignifit on my work computer which unfortunately runs Windows 7. As the required 64-bit MEX file is not provided, I’ve compiled it myself. TheĀ Psignifit MEX file for AMD64 can be downloaded from my website.

The 64-bit MEX files seem to be a bit unstable. I’ve noticed that this is because the variable index on line 2092 of psignifit.c can be nan. To fix this problem, the line should be changed from:

if(index < 0.0 || index > (double)(nVals - 1.0)) return NAN;


if(isnan(index) || index < 0.0 || index > (double)(nVals - 1.0)) return NAN;

Note that I did not yet recompile the Windows MEX file.

Color printing in Matlab on Linux

The Linux version of Matlab (2013a at least) defaults to printing in black and white. To print in color, you either have to specify another printer driver as an argument to print (“-dps2c” instead of “-dps2″) or manually select “color” from the “color scale” tab in the print preview dialog. The default for this setting is stored in: $MATLAB/toolbox/local/printopt.m. Look for the line that says dev = '-dps2'; and change it to dev = '-dps2c';.

While you’re at it, you can change default paper size, units and more by editing startup.m. My configuration looks like this:

set(0, 'DefaultFigurePaperType','A4');

set(0, 'DefaultFigurePaperPositionMode', 'Manual');
set(0, 'DefaultFigurePaperUnits', 'Centimeters');

set(0, 'DefaultFigurePaperOrientation', 'Landscape');
set(0, 'DefaultFigurePaperPosition', ...
[1 1 -2 -2] * 1 + ... % Set margin here
[0 0 29.7 21.0]); % Size of A4 in landscape format

Multi-functionals on Linux

[Important: You can skip the first part of this tutorial by generating a PPD for your printer. Thanks Wilbert!]

This document describes how to install the new multifunctions on (Ubuntu) Linux. While this procedure is pretty straight forward, things become a little bit more complicated in case account tracking is enabled. While bits and pieces can be found all over the web, I thought it would be helpful to consolidate everything in one document.

Account tracking

Before you can use account tracking, you need to install a CUPS filter and create a configuration file containing your credentials.

  1. Save the minolta filter to your Downloads directory.
  2. Open a terminal (press ALT-F2, then type “terminal”).
  3. Move the filter to the cups filters directory:
    sudo mv ~/Downloads/minolta /usr/lib/cups/filter/
  4. Make the filter executable:
    sudo chmod 755 /usr/lib/cups/filter/minolta
  5. Make a configuration file containing your credentials. The filter uses the printer name to find the file. You can freely choose your printer name, as long as it matches. I suggest using the name assigned by the University ICT department.
    sudo echo ACCOUNT_NAME=\"\" > /etc/cups/ppd/
    sudo echo ACCOUNT_PASSWORD=\"12345\" >> /etc/cups/ppd/
    sudo echo ACCOUNT_COETYPE=\"0\" >> /etc/cups/ppd/
    Note that you have to replace the bold bits! WordPress keeps changing my quotes, you might need to replace them.

Installing the printer

First, download the PPD for your printer. Note that these have been modified such that it uses the filter we’ve installed above. The original PPD files will NOT work with account tracking.

Then follow the steps below to install your printer:

  1. Open the CUPS administration panel http://localhost:631/
  2. Click the Administration tab
  3. Click Add printer
  4. Select “Windows Printer via SAMBA” at the bottom of the list.
  5. Enter the location (replace the bold parts):
    Special symbols should be percent-encoded (thanks to Micha Hulsbosch).
  6. Enter KM-PR0000 as the printer name.
  7. Click “Browse” and choose the PPD file you downloaded before.
  8. Click Add printer.
  9. Click the “General” tab.
  10. Choose A4 paper and “set default options”.

The printer should now work.

Bonus reading

You can set the name that appears when printing using:

You can directly contact the printer using:

You can store your prints in a box on the device using the following commands:
@PJL SET BOXNUM=314159265

Secure printing can be enabled using:
@PJL KMJOBID=”SecurePrintId”
@PJL HOLDKEY2 = “SecPassword”


EDF File format

In my current research, I track eye position using the EyeLink system. This system produces EDF files which I currently convert into ASCII files using a manufacturer supplied tool. Then, I parse this ASCII file using a custom built Mex file in order to get the data into Matlab. As I’ve always been particularly interested in figuring out how stuff works, this post documents my attempts to read the EDF files directly.

Every file seems to start with:
* A couple of information strings (each terminated by \n)
* And finally “ENDP:\n” which I guess is for end prelude.

The actual data follows. There seem to be a couple of types of variable length frames:
* 0F 00 21: Seems to contain sample frequency, possibly events or samples settings
* 11 00 21: Seems to contain sample frequency, possibly events or samples settings
* 18 xx 21: Seems to indicate the start of a string message
* 41 C0 21: Unknown
* 81 C0 21: Unknown
* D1 81: A sample with delta-time only
* F1 81: A sample containing full time stamp

I’m guessing that 0x20 indicates the presence of a full time-stamp. For some reason this does not hold for messages?

* 4 byte: time-stamp
* 1 byte: Unknown
* 2 byte: String length
* n byte: Null terminated string
* 1 byte: Null (there seem to be two)

* 1 byte: delta or 4 byte: time-stamp
* 2 byte: left x
* 2 byte: left y
* 2 byte: right x
* 2 byte: right y
* 2 byte: pupil ?
* 2 byte: pupil ?
* 2 byte: status (always 04?)