IODP Expedition 399 X-ray image logger (XSCAN)

Digital x-ray images were taken of core section whole-rounds (WR) or split section-halfs (SHLF) by the X-ray Image Logger (XSCAN). Each x-ray image was flatfield corrected using a dark calibration image taken with the camera shutter closed and white calibration image taken with the shutter open. The raw image width in pixels was determined by the distance between the calibration right crop and left crop pixels. Multiple scans of the same sample may have been taken at various rotational offsets. The 0 degree position along the rotational axis is the camera oriented vertically facing downward with the sample positioned below. The camera rotates around a stationary sample holder, completes an entire scan, returns to the starting position, rotates, then completes another scan. Scan speed and exposure time are relative and automatically adjust as one or the other are altered prior to a scan. To improve constrast, after each scan pixel intensities are scaled by reshaping the image intensity histogram using the histogram expansion factor and histogram anchor parameters. The operator selects the region-of-interest (ROI) to encompass only the sample material.