Embedding of digital watermarks to frequency and spatial areas of the image

Embedding of digital watermarking (DWM) is a technology of hiding messages in the digital signal (for example image, audio, video). It provides transferring of important information in the workflow system in production. Any digital signal may be used by the way of hiding information. The type of the signal affects the process of conversion only. This technology is applicable for system of workflow including aerospace industry. Through digital watermarks the important message can be transmitted, system information can be hidden in documents. DWM can help to protect contents of document including images and snapshots. In the paper as content static images were used, as transmitted information text messages were used. The digital image may be considered as a set of pixels with various brightness and colorfulness, so we can operate with it. Also we use frequency image’s domain, where we can manipulate with frequency coefficients to hide user’s information. Both approaches are widely used in marking technology. In the work process spatial method Least Significant Bit and frequency method of Koch-Zhao were used. These methods were compared by using quality assessments for resulting images which contains a digital mark. Numerical results were obtained by using known metrics: structure similarity and peak-signal to noise ratio. Experiments show the advantages of spatial methods against frequency algorithms in the cases when filled image was not exposed by distortion before a moment of extraction information message. In all other cases frequency methods are appropriated.