The Recording panel provides control for recording references and data. By default, perClass Mira imposes a data correction work-flow where dark and white references need to be acquired before data is recorded. The motivation is to make sure that modeling is performed not on raw but on reflectance-corrected data. This makes models robust to illumination changes.



The radio button group allows selection of different correction work-flows:

  • The default line (non-uniformity) means that full frame dark and white references are used to correct each pixel in the image. This is a recommended approach for most applications.
  • The Point setting means that we may define a scan area used to compute average white and dark spectrum that will be used for correcting all pixels. This is needed when a white reference cannot cover the entire field of view of our sensor (for example in remote sensing or outdoor applications).
  • The None setting disables referencing workflow and the acquired data will be used as is. This makes the developed models highly sensitive to illumination changes. It is generally useful only for situations where the sensor already provides reflectance-corrected data (Cubert, Imec) or where we wish to analyze raw data content. When selecting this option, recording tab is directly enabled.


The White and Dark references can be acquired from the sensor by pressing the respective buttons. The button Set from scan allows us to set the references from the currently selected image in Images list. Care needs to be taken that the references of this selected image really correspond to the current illumination conditions and camera settings.


The combo-box allows us to change the location of reference files. 



  • The directory-specific references are stored only once per entire directory in files named whiteref and darkref with the respective extensions for header (.hdr) and data (.pcf) content. This is advisable in situations where each of our data directories collects strictly only related files from the same scanning session. The resulting data storage is then cleaner and simpler.
  • The scan-specific references option means that each scan is accompanied by specific reference files named by appending _whiteref and _darkref to the scan filename. With this setting we may easily mix scans from different scanning sessions or days in one directory. Disadvantage of the scan-specific referencing is larger amount of scans in our data storage.


Both approaches can be mixed in our project, as this setting only affects the scans to be scanned in the future, not existing data.

Acquired references

Once the references are acquired, their time-stamps are and exposure times used are listed. Note that references should be acquired using the same exposure as the data. If you change exposure time, then references should be retaken before acquiring data. When the exposure set in the Camera panel differs from the exposure used when acquiring references, it will be emphasized by a red color in .


The Recording tab becomes enabled once both references are available. For the correction work-flow without references (None radio button), the recording tab is always available.