Keywords:  Grayscale, Look Up Table, Calibrate, Pixel Value, Annotation, GSDF
Image Quality

Thanks to DICOM standardization, a lot of improvements have been made in image quality consistency. The problem had always been how to achieve consistency in the image presentation of different monitors as well as on a film, independent from the make, type, and characteristics of the media.

The DICOM Greyscale Standard Display Function (GSDF) functions as a  gold standard for every monitor and hardcopy device, specifying exactly what luminance or density level would be produced for specific input values. The input values are mapped into a space that is perceived linear for a human observer. The result is that the images look all alike, so that when an image is sent from a radiologist to a physician, he looks at the same grayscale presentation.

In order to achieve this consistency, devices have to support the DICOM grayscale or color standard, potentially implementing a so-called presentation Look Up Table to map the values.  Vendors who offer solutions to access images have to ensure that the image is presented on a GSDF calibrated monitor for optimal mapping of the pixel values onto the available grayscale; and also deal with image integrity. The latter aspect allows an image to be viewed with the same window width/level setting, potential zoom, added annotations, etc. as the physician who did the initial diagnosis.

Premium Content(requires free registration) 
  • How Standards Make a PACS Run Better
  • Search Database