Double window: definition of a new pseudo-color mapping scheme for medical imaging

The number of gray levels in medical images significantly exceeds the range of human eye recognition. In this paper, we propose a series of definitions for real-time pseudo-color enhancement based on the hue, saturation, and value (HSV) color space. First, the definitions of gray window and color window are given as follows: in the HSV color space, the gray window means mapping pixel values to value, and saturation is set to zero. Thereafter, the color window was defined by mapping pixel values to hue, with the maximum saturation and value. Moreover, pixel values greater than the upper bound of the gray window were converted to hues in the double window. The images in the double window display the details shown in the lung window, mediastinal window, and bone window for chest computed tomography and showed more details than the grayscale image in brain magnetic resonance imaging. The proposed method enhances the display effect in some cases; for example, when the image histogram has more than one peak, the information displayed white in a regular grayscale image is displayed in color.