We are investigating histogram processing based image enhancement techniques to improve the ability of digital radiography (DR) for the detection of cardiac calcification. Computed tomography (CT) is an established tool for the diagnosis of coronary artery calcification. Digital radiography could be a cost-effective alternative. In this study, we assume that the DR image intensity values of calcified tissue have a Gaussian distribution. We use multiple Gaussian functions to fit the intensity histogram curve of DR images. Based on the mean and standard deviation parameters, we incorporated the histogram equalization enhancement method for each histogram portion of cardiac calcification. Thus, the calcification image was enhanced exclusively. We used three-dimensional (3D) CT images as the "gold standard" to evaluate the enhanced DR images for calcification detection. We acquired both CT and DR images from patients with coronary artery diseases. Experimental results show that the image enhancement method improved the ability of digital radiography for the detection of cardiac calcification.