Tuesdays are new patents days at the USPTO and this April Fools is no exception. Both of today's Spotlight issued patents address various aspects of watermarking. Assigned to Digimarc, the first patent addresses a human perceptual model applied to rendering of watermarked signals. Assigned to Hitachi, the second patent addresses digital-watermark-embedding and picture compression.
7,352,878, "Human perceptual model applied to rendering of watermarked signals," assigned to Digimarc.
A digital watermarking system uses a model of a rendering device to take into account the impact of the rendering device on visual or auditory quality of the watermarked signal. For visual content, a reference image and watermarked image are passed through the model and then supplied to a visual quality metric that assesses the visibility of the watermark. The digital watermark embedding is adjusted iteratively with each pass through this process to produce a watermarked signal that has the desired visual quality.
7,352,877, "Digital-watermark-embedding and picture compression unit," assigned to Hitachi (JP).
In order to avoid content deteriorations caused by embedment of a digital watermark into a moving picture, a process to search a picture for a motion and a process to filter a picture for medical care must be carried out, raising a processing cost. It is thus difficult to implement equipment for processing such pictures at a low cost. In a compound apparatus for encoding compressed code of a moving picture by employing a unit for embedding a digital watermark into a picture, a digital-watermark embedment quantity is determined by using a motion vector and a quantization parameter in a process to embed a digital watermark into the picture. It is thus no longer necessary to carry out the process to search a picture for a motion and the process to filter a picture for medical care for embedment of a digital watermark so that the cost of the entire apparatus can be reduced substantially.