In projection radiography, stationary grids are indispensable accessories to the improvement of diagnostic imaging. On the other hand, they are becoming one of the issues facing digital image processing. The lead foil that composes the grid can produce moiré on printed films and monitors according to the sampling interval at which the image is read by computed radiography (CR), creating a major obstacle to diagnosing images. The subject of this study on Grid Detection and Suppression (GDS) was the development of comprehensive image-processing software to detect and suppress grid lines automatically. Our results showed that applying GDS parameters 3 approximately 5 could provide a sufficient effect on suppression with little impact on images through the use of a multi-purpose grid (grid ratio 8:1, density 34 lp/cm) for general purposes. In projection radiography, it is expected that soft copy diagnosis will increase because the digital transition is proceeding, and the establishment of high-speed networks is becoming easier. Therefore, the digital environment is expected to improve and the choice of grids and monitors to expand, by using software such as GDS that does not require special skills.