The Digital Image Archiving System (DIAS) is an image management system, the major functions of which are preserving valuable digital images and serving as an image provider for external metadata archiving systems. To enhance the security of images, DIAS enables online adding of watermarks to an image to protect the content owner’s copyright. We use the Flash format to add watermarks because it has a multi-layer architecture and it can handle multimedia content. The function allows us to set the watermark as a layer that overlaps the original image. DIAS also provides an offline DRM (Digital Rights Management) mechanism to protect downloaded images. We package an image and its authorized information in an execution file for downloading. Then, when a user executes the file, the program validates the authorized information before showing the image. Using the watermark and offline DRM improves the security of DIAS images.