Knowledge Base

How Continuous Calibration Works

FaceReader continuously averages the facial expression intensities in the analysis.

Correcting Expression Intensities

With Continuous calibration, FaceReader corrects each expression intensity other than neutral in the following way:

Corrected expression intensity = max (0, (I_a - I_m))/ (1-I_m).

Where I_a is the intensity of that expression in the current frame and I_m is the average intensity of that expression over all frames before the current frame. If (I_a - I_m)/ (1-I_m) is lower than zero, the calculated expression intensity will be zero.

Correcting Intensity of Neutral

The intensity of Neutral is calculated in the following way:

Corrected Intensity Neutral = (N_a + (1- I_maxm))/2

Where N_a is the intensity of Neutral classified by FaceReader in the current frame and I_maxm is the average intensity of the expression with the highest average intensity in all the frames before the current one, excluding Neutral and Contempt.

Example

Consider the following average expression intensities:

• Neutral = 0.6
• Happy = 0.9
• Sad = 0.1
• Angry = 0
• Surprised = 0
• Scared = 0
• Disgusted = 0

This gives an I_maxm of 0.9

And a corrected intensity of Neutral of:

Corrected Intensity Neutral = (0.6 + (1 - 0.9)) / 2 = 0.35

Additional Options

What Do You Want To Do?

• Look for analysis information
• Recover analyses after an interrupted batch analysis
• Speed up analysis
• Move an analysis to another participant

Look For Analysis Information

Open the analysis.

Settings

Click the Analysis Settings button to view the settings for the current analysis. Most fields are editable.

See Settings for the Current Analysis

Source Details

Click the Source Details button to view information on the source of analysis, that is, the video file name, its location, duration, number of frames, frame rate, resolution and bitrate or in case of a camera analysis the camera name, its frame rate and resolution.

Track Bar

The Track bar at the bottom of the screen shows the following information:

• Video analysis — Progress of the analysis, the analysis speed (in fps), the running end time of the analysis, the end time of the video and whether the video has audio.
• Camera analysis — The analysis speed (in fps), the recording time left and whether audio is recorded. The maximum camera analysis duration is one hour. Please note that it is possible to run a camera analysis without recording video/audio.

Recover Analyses After An Interrupted Batch Analysis

An autosave file is created after each analysis. This is particularly important during batch analysis. If, for any reason, batch analysis is interrupted (for example after a power failure), you can recover the autosave file by renaming it to the original project file name. To do so:

1. Make sure FaceReader is closed.
2. Browse to the project folder and locate the file ~[project name]_Autosave (with no extension).
3. Rename the original project file to [project name]_backup.frx.
4. Rename the autosave file to the original project name.
5. Open the project again in FaceReader. There you should find all analyses completed before the interruption.

Speed Up Analysis

Carry out one or more options below to increase analysis speed.

• Select only the option Framing in the Analysis visualization window, or close the entire Analysis Visualization window.
• Close all visualization windows that you are not looking at. Each visualization slows down the analysis.
• Analyze every 2nd or 3rd frame instead of every frame. To do so, choose File > Settings > Default Analysis Settings. Choose one of the options under Video.
• Carry out only the analyses you require. Selecting Optional classifications decreases analysis speed.
• Do not keep other programs running in the background.

Move An Analysis To Another Participant

If you have multiple videos of the same participant and you accidentally added another participant to the project and added the second, third etc. analysis to the new participant, you can combine all the analyses of one participant. Right-click the appropriate analysis in the Project Explorer, click Analysis and then Move Analysis To Other Participant. Select the target participant and then Yes to confirm the move.

Source: FaceReader 10 Reference Manual (Help), Noldus Information Technology