Abstract: A technique is provided for a color imaging system having a luminance component and two color difference (chrominance) components, which allots more space in the compressed data stream to the signal component of greater information content or complexity; that is, which combines the encoding of the components of the data representing a common portion of an image in response to the actual needs of the component, prior to encoding the combined data. To this end, the calculation of the quantizing factors considers the combined information content of both the luminance and chrominance components for the same image location. Thus, low chrominance complexity allows the transmission of more of the luminance information, and vice versa. The system also provides for predetermining the relative complexity of the signal components to thus pre-allot the amount of space for each signal component in the compressed data stream in proportion to its measured complexity.

Abstract: Editing of information recovered from a relatively high speed communications medium such as a communications channel or magnetic tape often times allows only a portion of the information to be recovered. Storing information in complete segments from which portions of an image, called "snatches," may be recovered helps. An image signal is compressed in such a way that a snatch can be used during decompression to reconstruct a recognizable image from less than all the information that defines the image-thereby giving rise to the notion of a partially reconstructed image. The image information comprises several pixel data blocks with each block including sufficient pixel image data to reconstruct a portion of the image. The pixel data blocks are discrete cosine transformed ("dct") to generate a set of dct coefficient blocks.

Abstract: In a data compression process such as employed to compress video or other data, it is preferable not to compress the image data representative of the video image in a sequential format, or to take the data from the same area of the image. To equalize the information content of the data prior to compression, the present shuffling/deshuffling technique divides the video image into a multitude of image representing blocks, and selects a predetermined number of the image blocks from different spatial locations in the image, to form a succession of data sets representative of the video image information. That is, the selection of the image representing blocks is such that the information content (complexity) in each data set is similar to the information content in each other data set and further similar to the average information content of the entire video image.

Abstract: An image data compression technique is described which utilizes calculating means and a selected series of bit calculating stages having delays, to estimate one or more quantization parameters for such data. The estimation process preferably is iterated a number of times, with the values found through each estimation being used as the trial values for subsequent estimations. In addition, an initial trial value is selected by a data look ahead technique, which assures that its value is within range of the final quantization parameter used to quantize the data. The final quantization parameter insures that the compressed data fits within a predetermined number of encoded data bits to be transmitted or recorded, for example, in a recording medium.

Abstract: In a head displacement measuring apparatus, a folded optical path is used to introduce a collimated beam of light from a light source to a split photo detector, wherein both the light source and the split photo detector are mounted external of the support housing which secures and supports the flexible head assembly. A pair of optical prisms direct the light beam parallel to a head supporting blade integral with the head assembly. A Fresnel lens secured to the blade, preferably at the head end, varies the position of the path of the light beam in response to lateral displacement of the blade and head, to likewise vary the extent that the beam impinges one or the other of the photo detectors. The difference of the signals from the split photo detector provides a precise measurement of the transverse displacement of the head from a nominal centered position.

Abstract: Structures of magnetic heads having superconducting shields are disclosed for spatially directing magnetic recording/playback fields. One embodiment is a thin film magnetic head with a layer of superconductor material associated with its throat. Further embodiments provide intertrack shielding and concentration of recording/playback fields into relatively small pole tip regions.

Abstract: A pantographic head mount includes a pair of generally parallel flexible arms each solidly based at an inboard end and solidly affixed at an outboard end to a rigid structure that carries a magnetic head and is driven by an electromagnetic motor positioned to hold the head continuously normal to a recording medium while traversing across the medium. The structure is particularly adapted to resist torsional deformation. The two arms may be structured to have different resonant frequencies, and beating resonance between the arms during high-speed operation is avoided. However, in such case, the structures of the two arms are carefully matched to ensure that they still maintain the head continuously normal to the recording medium. In another embodiment, the arms have differently reticulated structural configurations to present incongruent but equal-area cross-sections at various points along the arm lengths.