VolMark is a software package for embedding "invisible" 3D watermarks (signatures) on digital, grayscale, 3D images (volumes) and detecting these watermarks. Such a scheme can be used for copyright Protection and "ownership" recognition of digital 3D images. A copyright owner can embed his personal key number as an "invisible" watermark on any digital, grayscale, 3D image. Later on, he can examine whether a given 3D image, which is suspected for being illegally copied, contains his own watermark (personal key number) and use it as legal proof. Copyright ownership proof for digital 3D images can be performed by using key numbers that: identify the author (copyright owner) and are embedded in the digital 3D image. Visible marks cannot be applied in the frames of the 3D image for this purpose, since they can be easily removed. In case of suspicion of theft, exhaustive search of the original in the copyright owner's Multimedia databases is a cumbersome and costly task. VolMark transforms the copyright owner's personal key number in an "invisible" watermark and embeds it in the body of the 3D image. The watermark can be easily detected by the copyright owner by using VolMark without any need to search in his multimedia database. Thus he can have a proof of ownership in the case of theft.Features:-The watermark is invisible. -Watermark discovery and removal by a third person is extremely hard. -WA number (greater than 50) of distinguishable watermarks can be produced (additional watermarks reduce extremely thequality of the image). -Watermark is resistant to JPEG compression up to low quality Factor (high compression ratio) and to various digital image processing operations. -Watermark detection in a suspected image is performed without the need of the original image. This saves time and money! -Eikonamark is user friendly.