Calibrating a COTS Monitor to DICOM Standard

Abstract

Abstract We present a method for calibrating a commodity, off-the-shelf (COTS) monitor (costing in the region of £200) to produce a greyscale image approximately calibrated to the DICOM standard, rather than require a 10-bit radiology monitor (costing in the region of £10,000). We use the concept of PseudoGrey to extend the available shades of grey from 256 to 5,800, which is in excess of a 12-bit greyscale. The chromaticity of the resulting greyscale is analysed to verify that the colour introduced does not unduly detract from a pure greyscale image. The behaviour of low intensity levels in the COTS monitor is also analysed, showing that a naive approach to estimating luminance from individual passes through the red, green and blue components is insufficient to produce an accurate intensity range. The results show that we can achieve a basic DICOM calibration (with FIT and LUM tests), but we have yet to test for further variability (such as off-axis deterioration in brightness or inconsistent luminance across a display). As well as displaying medical images, this approach may be of use in other areas requiring a high dynamic range, such as thermal imagery or images taken through multiple alternative exposures.