Automatic adjustment of contrast and brightness of magnetic resonance images

Two statistics of the magnetic resonance (MR) image, the median and the standard deviation of the values of the significant pixels, can be used along with the type of image to adjust the contrast and brightness of the image (ie, to "window" it) automatically and robustly. The essential parts of this approach to automatic windowing are (1) avoidance of irrelevant pixels, (2) identification of the type of MR image from information stored in the image header, and (3) use of algorithms for the maximum and minimum values that reflect the preference of the intended viewer using a specific monitor and ambient lighting conditions for the different types of images. An evaluation in thirteen clinical studies yielded 91.5% (2312/2526) images requiring no further adjustment and the remaining 8.5% (214/2526) being improved by further adjustment.