Abstract: A method of image processing for conversion of an image in a sequence of images comprises the steps of associating pixels of an image with respective motion values indicative of a degree of inter-image motion for each pixel; adjusting the motion value of each pixel based upon the motion value of a secondary pixel found within a first region of a first predetermined size substantially centered upon each respective pixel, said secondary pixel being that whose associated motion value is indicative of the greatest motion of any pixel in the first region; adjusting the motion value of each pixel based upon the motion value of a secondary pixel that lies within a second region of a second predetermined size substantially centered upon each respective pixel, said secondary pixel being that whose associated motion value is indicative of the least motion of any pixel in the second region; categorizing each pixel as a static pixel or a motion pixel according to its respective associated motion value, and then selecting

Abstract: An image processing method for image conversion by combining two or more source values based on a mixing parameter to generate an output pixel value. A metric is calculated for a selected pixel at a given image field based on the directly preceding image field and a spatially interpolated version of the given image field at the selected pixel position. The selected pixel is categorized based on the metric as providing an indeterminate, unreliable, or reliable basis for a determination of motion at that pixel. The mixing parameter for the selected pixel is adjusted based on the categorization of the pixel.

Abstract: An image processing apparatus includes a first motion detector, a second motion detector and a conversion selector. The first motion detector detects motion to a first level of spatial frequency sensitivity. The second motion detector detects motion to a second level of spatial frequency sensitivity greater than the first level of spatial frequency sensitivity to detect smaller amounts of motion than the first motion detector. The conversion selector selects contributions from at least one of a first conversion process and a second conversion process for a given point in an image dependant upon whether motion is detected by the first motion detector at the given point or not. The conversion selector operates independently of the second motion detector if a degree of motion within the image or a part thereof including the given point detected by the first motion detector does not exceed a threshold amount.

Abstract: A video data network device arranged to receive a video signal and an associated synchronisation signal and to launch video data packets representing the video signal onto a packet-based data network comprises means for detecting whether the video signal is synchronised with the synchronisation signal; and means for launching data onto the network indicating whether the video signal is synchronised with the synchronisation signal.

Abstract: An image processing apparatus generating output pixel values with respect to pixels of an input image selected in accordance with an image feature direction in the input image and including a comparing mechanism comparing blocks of pixels of the input image, the blocks disposed with respect to a pixel position under test so that a correlation between the blocks would indicate an image feature direction applicable to that pixel position; and a validating mechanism detecting whether an image feature direction may be used to interpolate an output pixel value at the pixel position under test. The validating mechanism: (i) detects whether a detected image feature direction for the pixel position under test meets one or more predetermined directional criteria; and (ii) detects whether pixel values in image regions disposed with respect to the pixel position under test in accordance with possible image feature directions meet one or more predetermined pixel value criteria.

Abstract: A data compression apparatus for performing data compression on input data comprises a quantisation parameter estimation arrangement for deriving an estimated value of a quantisation parameter used in a previous compression/decompression cycle applied to the input data, by detecting rounding effects in data values of at least a subset of the input data; and a parameter selection arrangement, responsive to the quantisation parameter estimation arrangement for selecting a quantisation parameter for use in compression of the input data.

Abstract: An image processing apparatus for image conversion comprises first motion detecting means operable to detect motion to a first level of sensitivity; second motion detecting means operable to detect motion to a second level of sensitivity, the second level of sensitivity being of greater sensitivity than the first level of sensitivity so that the second motion detecting means can detect smaller amounts of motion than the first motion detecting means; conversion selection means operable to select respectively either a first conversion process or a second conversion process for a given point in an image dependant upon whether motion is detected at that point or not, and in which the conversion selection means operates independently of the second motion detecting means if the degree of motion within an image or a part thereof detected by the first motion detecting means exceeds a threshold amount.

Abstract: A method of image processing for converting interlaced images to progressive scan images comprises the steps of generating a motion dependent mixing value for determining the extent to which a preceding image field should be mixed with a current intra-field interpolated image field at a given pixel position, comparing the generated mixing value with a preceding historical mixing value, and if the comparison indicates an increase in motion, using the generated mixing value; otherwise, if the comparison indicates a decrease in motion, temporally filtering the generated mixing value prior to use.

Abstract: An image processing apparatus for image conversion comprises calculating means operable to calculate a first metric for a selected pixel position in a current image field, the first metric being the difference between a directly preceding image field and a spatially interpolated version of the current image field at the selected pixel position; categorising means operable to categorise, on the basis of the first metric, whether the selected pixel in the current image field provides either an indeterminate, unreliable or reliable basis for the determination of apparent motion at that selected pixel position in the current image field; and adjustment means operable to adjust a parameter associated with the selected pixel depending upon the categorisation made.

Abstract: A method of image processing for conversion of an image in a sequence of images comprises the steps of associating pixels of an image with respective motion values indicative of a degree of inter-image motion for each pixel; adjusting the motion value of each pixel based upon the motion value of a secondary pixel found within a first region of a first predetermined size substantially centred upon each respective pixel, said secondary pixel being that whose associated motion value is indicative of the greatest motion of any pixel in the first region; adjusting the motion value of each pixel based upon the motion value of a secondary pixel that lies within a second region of a second predetermined size substantially centred upon each respective pixel, said secondary pixel being that whose associated motion value is indicative of the least motion of any pixel in the second region; categorising each pixel as a static pixel or a motion pixel according to its respective associated motion value, and then selecting r

Abstract: A data encoding apparatus operable to encode a plurality of data blocks produces encoded data in accordance with at least one of a selectable target data quantity or a selectable target data quality.

Abstract: An encoding apparatus operable to encode video data representing successive images, each image including a plurality of pixels. The apparatus includes a differential encoder arranged to encode each image as one or more predetermined image regions. Each image is being encoded as a reference value and at least one differential pixel value. The differential pixel value(s) are derived in dependence on the reference value and/or other differential pixel value(s) in accordance with an order of encoding dependency; in which, for each image region, the differential encoder is operable in a first encoding mode for a first subset of the images to encode the image region using a first order of encoding dependency and in a second encoding mode for a second, different, subset of the images to encode the image region using a second, different, order of encoding dependency.

Abstract: A decoder 2 decodes a first compressed digital video bitstream whilst preserving the compression parameters thereof, the compression parameters including a first buffer occupancy value VBV—1 representing the occupancy by the said first bitstream of a buffer of the decoder. A signal processor 40 processes the decompressed bitstream. An encoder 6 compresses the processed bitstream to produce a second compressed bitstream having a target bit rate, optionally with reuse of the said compression parameters of the first bitstream, the second bitstream having a second occupancy value VBV—2 representing the occupancy of a downstream decoder buffer by the said second bitstream.

Abstract: Decoders A and B decode MPEG-2 bitstreams A and B. A switch (S1) switches from decoded stream A to decoded stream B to achieve a splice. The resulting bitstream is re-encoded in an encoder 4. A new transitional GOP is defined beginning at the splice. The new GOP is defined by picture type decision rules which may have the effect of changing the GOP compared to the GOPs of streams A and B. The new GOP provides an initial prediction of the position in stream B where the occupancy value of stream C should coincide with that of B. A target for the new number of bits in the new GOP is calculated as the sum of the normal allocation of bits for the new GOP plus the difference between the occupancy value of stream C at the splice and a prediction of the occupancy of stream B at the predicted position. The occupancy value of stream C is controlled in accordance with the target so that it tends towards the occupancy value of stream B at the predicted position.

Abstract: A data processing system comprises a data compression decoder arranged in operation to decode first and second encoded data to produce first and second uncompressed data representative of first and second source data from which the first and second encoded data were produced in accordance with a compression encoding algorithm respectively. The data compression decoder also produces first and second compression parameter data representative of encoding decisions made by the compression encoding algorithm when the first and second source data was compression encoded.

Abstract: A data compression apparatus includes a source detection arrangement for detecting whether or not the input data is source data that has not undergone a previous compression/decompression cycle; a data quantity generator, responsive to the source detection arrangement, for setting a desired data output quantity for the compressed data, the desired data quantity having a first value for source input data and a second, higher, value for non-source input data; a target allocator for allocating a target data quantity to respective subsets of the input data in dependence upon the desired output data quantity, the target data quantities together providing a desired output data quantity; and a data compression arrangement for compressing each subset of the input data in accordance with its respective target data quantity.

Abstract: Decoders A and B decode MPEG-2 bitstreams A and B. A switch (S1) switches from decoded stream A to decoded stream B to achieve a splice. The resulting bitstream is re-encoded in an encoder 4. A new GOP is defined beginning at the splice. The new GOP is defined by picture type decision rules which may the effect of changing the GOP compared to the GOPs of streams A and B. The new GOP provides a prediction of the position in stream B where the occupancy value of stream C should coincide with that of B. A target for the new number of bits in the new GOP is calculated dependent on the difference between the occupancy value of stream C at the splice and a prediction of the occupancy of stream B at the predicted position. The occupancy value of stream C is controlled in accordance with the target so that it tends towards the occupancy value of stream B at the predicted position.

Abstract: Video signal processing apparatus in which at least two input video signals are combined in proportions determined by a pixel key signal to generate an output video signal for compression, at least one of the input video signals each having respective associated compression parameters from a data compression process applied to that video signal; comprises: means for detecting an average pixel key signal value across each of a plurality of blocks of pixels of the output video signal; and means for comparing the average pixel key signal values with first and second thresholds, the first threshold representing a pixel key signal value corresponding to combination having primarily one of the video signals, and the second threshold representing a pixel key signal value corresponding to combination having primarily the other of the video signals; in which: if the average pixel key signal value for a block lies between the first and second thresholds, that block of the output video signal is compressed using new

Abstract: Data compression apparatus for compressing an input data unit to produce an output data unit in accordance with a desired data quantity of the output data unit, the degree of compression being determined by a compression control variable having a range of possible values. A trial encoder compresses successive sections of the input data unit in accordance with a trial group of two or more values of the compression control variable. A data quantity detector detects the trial data quantities generated by each trial encoding of the sections of the input data unit and selects a base compression control variable applicable to the input data unit on the basis of the detected trial data quantities, in order to comply with the desired data quantity.

Abstract: A method of mounting a volume from a tape medium on a tape drive apparatus. The method reads a bar-code indicating the volume from a tape cartridge, attaches the tape cartridge to a tape drive, and detects the current track position on the basis of a longitudinal track. The method then determines whether a beginning volume label or a last used area volume label is nearer to the current track position, reads the nearer volume label from the tape medium, confirms the volume by comparing the nearer volume label with the bar-code, and mounts the volume onto the tape drive.