Abstract: Compressibility-reducing artifacts are added to redundant areas of color images and video sequences. A first artifact change is made to a luminance component of a redundant area, and at least one other artifact change is made to chrominance components of the redundant area. The artifact changes are perceptively balanced such that the artifacts are not perceptible when the image is displayed on a monitor. However, the artifacts reduce redundancy in the image and, therefore, reduce compressibility of the image. In order to recompress a copied image, either the quality of the image must be reduced or file size of the image must be increased. Increasing file size will make redistribution impractical. Consequently, attempts to make and redistribute unauthorized copies of video images and sequences will be discouraged.

Abstract: Image-distorting artifacts are added to selected areas of a color image. A first artifact change is made to a luminance component of a selected area, and at least one other artifact change is made to chrominance components of the selected area. The artifact changes are perceptively balanced such that the artifacts are not perceptible when the image is displayed on a monitor. For example, changes in saturation are selected to balance changes in intensity of luminance. However, when the image is filtered such that one of the artifacts is modified, the remaining artifact becomes visible. Such filtering might be performed by an RGB-to-NTSC converter. Thus, if the RGB-to-NTSC converter is used between an RGB output of DVD-ROM electronics and a computer monitor (in an attempt to make an unauthorized copy), the video signal leaving the RGB-to-NTSC converter will contain perceptible artifacts and, therefore, images of reduced viewability.

Abstract: An optical storage device includes a laser, a write clock generator and a read/write disc. The laser is modulated, and a readback signal is generated from laser light read back from the disc. The readback signal includes a first frequency component caused by the modulation of the laser and a second frequency component caused by information (e.g., data or a high frequency wobble) on the medium. Phase of the write clock is adjusted in accordance with a phase difference between the first and second frequency components. This adjustment allows new data to be written to the read/write disc without a phase discontinuity between the new data and data previously written to the disc.

Abstract: A system and method for generating a write clock for writing data along servo tracks of an erasable/rewriteable optical disk utilize clock patterns that correspond on a one-to-one basis to designated data zones on an optical disk. The clock patterns are located in one or more clock tracks and are dedicated to providing reference clock information. In one embodiment, an optical disk is divided radially into constant angular velocity (CAV) data zones and corresponding circular clock tracks are located near the outer edge of the disk. The circular clock tracks correspond on a one-to-one basis to the CAV data zones, and the unique clock patterns within the clock tracks are utilized to generate write clock signals. Clock information is read by a dedicated reference clock transducer and data is written to and read from a servo track of an optical disk by a read/write transducer.