Abstract: An anchor for securing a perimeter of a cover about a pool. The inventive device includes an elongated anchor assembly positionable about a perimeter of the pool. Securing straps couple the anchor assembly to the perimeter edge of a cover extending over the pool. The anchor assembly is preferably formed of a plurality of conduits which can be filled with water to increase a weight of the anchor assembly to a desired amount.

Abstract: A method and apparatus for viewing the effect of outputting on the output device an image represented by digital data defining the colour content of pixels of the image. The apparatus comprises a monitor; a store; and a processor to enable a portion of the image to be selected, and for generating and storing in the store data simulating the selected image portion as it would appear after screening by the output device. The monitor is responsive to the stored data to display the simulated, screened image portion.

Abstract: A method of generating a graphics pattern comprising digital data defining the color content of pixels of the pattern within a pattern area at a first, high resolution, comprises defining (step 21) the color content of "seed" pixels at selected positions within the pattern area which are to influence the resultant pattern. The remaining pixels at the first high resolution are considered as having undefined color content. Successively lower spatial resolution versions of the pattern area are generated in accordance with a predetermined algorithm which, when sufficient defined pixels exist in the next higher resolution version neighboring an undefined pixel, interpolates color data for the corresponding lower resolution pixel, until all pixels of a lower resolution version contain defined data (step 25).

Abstract: Electronic image generation apparatus includes a monitor, a colour data array for storing digital data defining the colour component content of pixels of an image, a control data array for storing control data for each display pixel, and a mixer connected to the control data array and the colour data array for generating display pixel data comprised of a combination of proportions of the data in the colour data stores and other colour data the proportions being in accordance with the control data. The monitor is responsive to the display pixel data. A camera views a region within which an indicator may be moved, and is connected to the control data array such that data relating to the appearance of the region is recorded in the control data array.

Abstract: A method and apparatus for compressing digital data defining the colour component content of pixels of a coloured image, the apparatus comprises a processor (1) for performing a principal component analysis on each of a number of non-overlapping blocks of pixels making up the image to determine the principal component vectors corresponding to the block; for rounding the principal component vectors to a fixed set of intervals; for transforming the original pixel data into the colour space defined by the rounded principal component vectors; for performing a compression algorithm on the transformed pixel data; and for performing a separate compression algorithm on the rounded principal component vector values.

Abstract: Apparatus for interactively modifying an image represented by digital data defining the color content of pixels in the image in terms of color components defining a first color space comprises a store (1) for storing the original image; a look-up table (2) for transforming the image into a second color space (LCH) and a store (3) for storing the second color space representation. The second color space is defined by second color components having a reduced resolution relative to those of the first color space. The representation in the second color space is fed through a look-up table (4) whose contents can be controlled by an operator so that the image at low color resolution can be retouched interactively, the retouch version being displayed on a monitor (6). Once a satisfactory retouch has been achieved, the original image in the store (1) is modified and stored in the first color space in a store (13).

Abstract: Apparatus for generating an array of control data, the array having a number of pixels each of which corresponds to a respective pixel in an image, the apparatus comprising a first store (100) for storing the image data; a second store (17) for storing the control data; and a processor which, for each control data array pixel generates and stores in the second store (17) a control value in accordance with a predetermined algorithm which defines the control value as a function of the corresponding image pixel color components and the corresponding color component(s) of the target colors, wherein the generated control values can be ordered on a scale of at least three value classes.

Abstract: A method of compressing digital image or image-like pixel data. The method comprises carrying out the following steps on small blocks of pixels:a) determining the differences between digital values of adjacent pixels in the block to define respective link weights;b) determining a tree connecting all the pixels in the block such that the sum of the link weights in the tree is a minimum;c) dividing the tree into segments by removing links with weights greater than a threshold value, so dividing the block into segments of linked pixels;d) generating a segmented representation of the block by setting the values of all pixels in each segment to a single, respective, representational value; ande) compressing the segmented representation to generate compressed data.

Abstract: A method and apparatus for generating a half-tone version of an image represented by a first set of digital data defining the colour content of abutting pixels of the image at a first resolution. The apparatus comprises a radiation beam generator (8); a recond medium support (11), wherein the radiation beam and the support are relatively moveable such that the radiation beam scans a record medium (10) mounted on the support in a series of abutting scan lines; a radiation beam modulator (7) for modulating the radiation beam in response to a control signal (CS); and a control signal generator (5) for generating the control signal. The radiation beam is modulated selectively to expose a record medium on the support (11) at a second, finer resolution, the control signal generator (5) being adapted to interpolate the second set of digital data from the first set of digital data and to generate the control signal by comparing the second set of digital data with half-tone information.

Abstract: In order to reduce thermal coupling between diodes in a light emitting diode array for a printing or imaging system which has the undesirable effect of wavelength shift and output reductions, rows (12, 14) of diodes are provided which are separated and inclined to the direction (Y) of scanning movement during a print operation, wherein current pulses applied to the diodes of each row for energization are delayed with respect to one another such that energization and printing occurs in a line perpendicular to the direction of scanning movement.

Abstract: A method of alignment of monolithic chips of arrays of light emitting diodes to form part of a print head, the method comprising placing microscopically visible alignment marks on each chip in predetermined positions relative to the diode array carried on the chip, positioning two chips adjacent to one another in desired relative positions, and viewing the two chips through a microscope having a graticule, whereby the alignment marks of the two chips are positioned on the cross wires of the graticule whereby the chips are aligned with their respective diode arrays in a correct spacing and orientation relative to one another.

Abstract: A simple and reliable method of recalibrating a LED print head comprises providing a photodetector array for detecting the intensity of illumination of each LED, comparing the actual intensity with a desired value and adjusting the level of current applied to the LED array until the actual and desired values correspond, at which time a memory storing the current levels to be applied to the diode array is updated. One or more reference diodes are provided and employed in an initial step in which the current applied to the reference diodes is adjusted until actual and desired current levels correspond, at which time all stored current values for all LED are updated.

Abstract: A method and apparatus for enhancing a video image defined by luminance information and chromaticity information comprises, for a number of selected regions of the image,(a) determining using a microcomputer (22) a statistical relationship between the luminance information and the chromaticity information for the selected region; and,(b) generating modified chromaticity information for at least a portion (1) of the selected region by applying the determined statistical relationship to the luminance information for the said portion.