DICOM image consistency deals with displaying the images in an identical manner on soft and hard copy devices, using a standard mapping from digital driving levels to luminance on a monitor or density on hard copy.

Image display consistency is a major issue that hampers the implementation of PACS using softcopy viewing. The key to preserving the image quality of a display is to calibrate the monitor at regular intervals. There is no ideal display characteristic curve for mapping digital driving levels into luminance values. However there is a gold standard that could be adhered to.
This characteristic curve is generated by mapping just noticeable differences (JNDs) onto the light output (luminance) of a monitor or onto the optical density of a film. It is called the Grayscale Standard Display Function (GSDF).

Using this standard, monitors and printers can be calibrated with the help of calibration tools. One can use a tool that includes a luminance meter. Many of these tools have a suction cup that can be placed on the monitor. This allows the light output (luminance) to be measured.
This light output can be compared with the actual GSDF, and any differences can be calculated and saved. The number of measuring steps to make a good approximation of the curve is less than 30. Most tools automatically vary the input values. Once can purchase this as a kit that comes with a Look Up Table (LUT), which can be downloaded to the specific video display controller, or saved and used by the display software.




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