Abstract: An intraosseus shunt can comprise a shunt body and a valve. The shunt body can be configured for insertion into bone and can have a fluid inlet, a fluid outlet, and a flow passage extending within the shunt body between the fluid inlet and the fluid outlet. The flow passage, the fluid inlet, and the fluid outlet can be configured for cerebrospinal fluid flow therethrough to cancellous bone. The valve can be attached to the shunt body and configured to control flow through the flow passage. A method of shunting biological fluid away from a hyper-pressurized biological cavity to a bone can comprise (i) creating a passage through cortical bone to provide access to cancellous bone, and (ii) positioning the shunt into the passage. The valve can control communication between the biological cavity and the cancellous bone.

Abstract: An image data recording and transmission system is described in which a data compressor 76 decorrelates input image data into sub band component data, a data recorder 78 stores the sub band data, a data decompressor 80 decompresses data read from the data recorder and a transmission signal generator 82 produces a bandwidth limited transmission signal from the decompressed data. The combined action of a data sequencer 18, a quantiser 14 and an entropy encoder 20 within the data compressor act to remove from the data stream that information corresponding to frequencies not transmittable with the bandwidth limited transmission signal (e.g. PAL or NTSC) subsequently produced by a transmission signal generator 82. Accordingly, the data recorder need not use storage capacity recording data which cannot be used by the transmission signal generator.

Abstract: Apparatus for recording and reproducing video data is described that utilizes data compression to increase storage capacity. Real time input video data is decorrelated, quantized and entropy encoded. User control of a compression control parameter, such as quantization step width, is provided so that the user can adjust the loss of fidelity through compression to a desired level. The compressed data is output to a storage RAM 38 at an unregulated varying data rate. The system allows real time storage of video data in a manner in which the loss of fidelity is held constant and the amount of storage capacity required for particular sections of input video data varies with the information content of that input video data.

Abstract: A signal processing system includes a compression encoder 16 for compressing an input block of data samples including a plurality of sub-blocks, each sub-block including an array of data samples, into a block of compressed data. A sequencer 14' accesses the data samples of the input block to be passed to the compression encoder 16 with the sub-blocks being accessed in a predetermined first order and the data samples within each sub-block being accessed in a predetermined pseudo-random order such that successively accessed locations in the array of samples for a sub-block are scattered throughout that sub-block. The pseudo random accessing sequence enables occupancy of a buffer 73 for the compressed data block to be linearised. The sequencer can include a counter 62, the output of which addresses a look-up table 65 for generating the pseudo-random sequence in a repeatable manner.

Abstract: Data to be processed is stored within data files 20. Associated with each data file 20 is a header file 18. The header files 18 store data specifying a wide range of attributes of the data within the data files 20. A user selects a particular signal processing function 14 that he desires to use and this then accesses one or mope selected data files 20 and associated header files 18. The selected signal processing tool 14 only needs a set of the attributes stored within the header files 18. The signal processing tool 14 reads those attributes it requires and then manipulates the data within the data file 20. The provision of this structure allows a wide range of signal processing function tools to be integrated into a single system which may also be simply expanded.

Abstract: A two stage data formatter is described for converting variable bit length code words into fixed bit length code words. The second formatting stage 12 splits the words into complete fixed length code words and returns any remainder bits to the first formatting stage 10. The first formatting stage 10 preprocesses the following data words by concatenating any remainder bits with the following variable bit length code word and updating its corresponding bit length code word. These preprocessed data words are then passed to the second formatting stage 12.

Abstract: A serial data decoder is described for decoding interleaved variable length and fixed length codes. The decoder includes a state machine which moves between a branching hierarchy of states in dependence upon the bits of received serial data. When the state machine reaches a state corresponding to a complete variable length code having been received, it then enters a delay state lasting for the length of time necessary to receive the following fixed length code prior to return to a reset state. The state machine can be implemented using a static ram 10 storing data including pointers for controlling the movements between states.

Abstract: Image processing apparatus is described in which a source stream of data captured by a particular source is passed through a data splitter where it is split using one splitting technique into a plurality of split streams of data. These split streams of data each contain only part of the information within the source stream of data. The split streams of data are separately manipulated by a post production unit prior to being passed through a data combiner where they are recombined to form an output stream of data. The source stream of data and the output stream of data are of a higher resolution than the individual split streams of data. The post production unit includes at least one reformatter for reformatting the data stream to use a different splitting technique matched to the manipulation being performed in the post production unit.

Abstract: Image processing apparatus is described for filtering a digital representation of a raster scanned image into a plurality of sub-bands in the two-dimensional spatial frequency domain, the resolution of the raster scanned image in a first direction (usually the horizontal direction) being greater than the resolution of the raster scanned image in a second direction (usually the vertical direction). The image processing apparatus has a decimation filter means comprising a number of multi-tap digital decimation filters for spatial filtering in the first and second directions. The mean of the filter lengths of the filters used for filtering in the first direction is greater than that of the filters used for filtering in the second direction. Complementary interpolation apparatus for reconstructing the image from the plurality of sub-bands is also described.

Abstract: A data encoder is described for carrying out runlength coding. A count of zero input data values is made by a runlength counter 10. The input data values are simultaneously fed to a encoded word bit length indicator 6 and encoded word generator 8 which respectively produced outputs for each input data value. An encoder state machine 12 triggers the reading into an encoder data store 16 of the current runlength, encoded word bit length and encoded word at appropriate times. The encoder state machine triggers storage when a non-zero input data value is received. The encoder state machine 12 also prompts the generation and storage of continuation codes (corresponding to a predetermined maximum of zero input data values) and end of block codes (corresponding to an indication that all the subsequent input data values within a current block are zero values and can therefore be ignored) when appropriate data streams are encountered.

Abstract: A sub-band filter system in which the frequency separated data is multiplexed together at the output of each filter stage. The stream of multiplexed data produced can have a block-by-block format or a sample-by-sample format. In the latter case, the filtering can be effected by a finite impulse response filter with switchable tap coefficients for effecting both decimation and high and low pass filtering.

Abstract: A data compression system in which decorrelated data is fed to an entropy encoder (20) in batches having an internal monotonic decrease in average information content from start to end. This results in longer zero runs and more rapid attainment of end of block codes. A data sequencing circuit (18) comprising nested inter-sub band (60) and intra-sub band (72) counters for use with sub band filtered video data is also described.

Abstract: Apparatus for storing a video signal includes a signal compression arrangement constituted by a spatial two-dimensional sub-band filtering arrangement that filters a digital video signal to form data sets constituting respective sub-bands of the two-dimensional spatial frequency domain, a quantizer that quantizes the data sets in accordance with respective values which are such that the amount of quantization of one of the data sets constituting a sub-band to which dc luminance information of the signal is at least predominantly confined is less than the average of the amounts of quantization of the remaining data sets, and an entropy encoder that selectively encodes at least some of the quantized data sets so that the quantized data sets, as selectively entropy encoded, form a compressed video signal. The signal compression arrangement is followed by a storage arrangement for storing the compressed video signal.

Abstract: A digital video signal is compressed by spatial sub-band filtering to form data sets constituting respective sub-bands of the two-dimensional spatial frequency domain. The data sets for a field or frame are stored. A first sequencer controls writing, in accordance with a desired sequence, of the stored data to a quantizer in which they are quantized in accordance with respective values, those values being such that the amount of quantization of at least a data set constituting a sub-band to which dc luminance information of the signal is at least predominantly confined is less than the average of the amounts of quantization of the remaining data sets. The quantized data sets are then encoded in an entropy encoder which has a first coding portion for coding quantized data representative of dc luminance information and a second coding portion for coding quantized data representative of ac luminance information.

Abstract: To enable a digital composite color video signal (NTSC or PAL) to be compressed directly, that is without dividing it into its components and compressing the components separately, the digital composite color video signal is decorrelated, for example by spatial sub-band filtering, to form data sets, for example sub-bands, representing dc luminance information, ac luminance information and dc chrominance information. The data sets are then quantized in accordance with respective quantization values from a quantization matrix, those quantization values being such that the amount of quantization of each of some of the data sets to which the dc luminance information and the dc chrominance information is at least predominantly confined is less than the average of the amounts of quantization of the remaining data sets. At least some of the quantized data sets are then entropy encoded.