Pseudocolor Coding of Medical Images Based on Gradient

Pseudocolor coding is a common method in medical images enhancement and display. The key technology is gray-to-color mapping functions. According to the features of medical images and human visual system, this paper develops a new nonlinear pseudocolor coding method based on gradient value. Firstly, we get the gradient image and define a threshold according to the gradient operator. Then, compared to the threshold, if the gradient is bigger than it, we code pixels with red on the basis of their gradient values. Otherwise, we define two thresholds to delimit the different extents according to gray values, again. And design nonlinear, sine transformation functions to code them. Due to the choice of three parameters kl,k2 and k3 in the mapping functions, this method adds the flexibility. This method is tested and compared by many experiments. It can make the outline of the medical images clearer and effectively highlight the disease areas, so the results improve doctor´s diagnoses.