• How it works

    Sierra Colour Calibration


    Production of Colour Calibration Slides for Pathology

    • Stained tissue creates a large and unique gamut of colours.

    • Digital Pathology needs to account for this colourimetric biochemistry.

    • FFEI’s patented Sierra technology precisely mimics biologically stained tissue.

    • This unique feature creates coloured patches with spectral transmittance near-identical to the gamut of stained tissue.

    • Different stains at different concentrations produces a metamerism-free range of hisological/cytological colours.

  • Unique Measurement of Intensity Data

    • Spectral data for each patch is obtained using a high-precision spectrophotometer.

    • Equipment calibrated to National Physics Laboratory standards and ICC values ensures spectral accuracy.

    • This spectrally ‘true’ data is unique to each individual slide.

    • Eliminates variation in production and enhances precision and traceability.


  • Step 1


    Sierra slide scanned

    • The Sierra slide is scanned by the WSI instrument to be calibrated.

    • Output data contains the colour intensities interpreted by the non-calibrated scanner.

  • Step 2

    Assessment of Scanner Accuracy

    • Colour interpreted by the scanner can be compared to original Sierra data, known to be ‘true’ to precise ICC values.

    • The accuracy of colour scanned relative to truth represents that WSI systems error across the stained tissue gamut.


    Step 2

  • Step 3


    ICC Profile Creation

    • With ‘error’ for each colour quantified, generic colour profiling can be updated with the device-specific ICC profile.

    • The scanner’s fidelity to colour ‘truth’ is quantified, calibrated and corrected.

    • Crucially, this process does not interfere with the tissue image data itself – all pathology data remains for the pathologist.

    • This parallel metadata allows for software to represent the true colour data of each image.