Processing the data

After they are exposed in the field, the slides are sealed. This provides a permanent record of the collected dust which may be used for additional investigations (geochemistry, mineralogy etc) or proof of evidence. The samples are scanned on a flat bed scanner and this output is saved in uncompressed TIFF format. These image files comprise the raw digital data for subsequent analysis.

The TIFF image files are then analysed. The initial visual display presents the scan in colour and comprises the sample area and the unexposed reference area (used for calibration). The processing steps are outlined below.

Initial processing masks out areas not used in the analysis (such as flies, seeds, fingerprints etc). The reference area is then set and calibration value established for each individual slide against which the soiled area is compared. Masking is achieved either manually or automatically. Masking is shown on the screen as a green colour change.

The dust levels for each sample are assessed individually with approximately 150,000 data points being analysed per sample. The process is reliable, non-subjective and repeatable.