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AssigneeInternational Business Machines Corporation
InventorsJohn F. Minshull, Pavel Brazdil
Estimating the term…
Data manipulation apparatus is described for converting raster-scanned data received, for example, from a scanner 2 at a first picture element (pel) resolution to a second lower pel resolution for display, for example, on a CRT terminal 4. The apparatus includes a scale-changing means 8 which functions to replace selected subgroups of pels in the input image by single pels at its output. The significance of each single pel reflects the presence or absence of a pel representing part of an image object in the associated subgroup of pels. The number of pels in the selected subgroups are determined by the degree of compression required to convert to the lower pel resolution. Prior to scale change, the apparatus functions to modify the input data in order to minimize merging of adjacent image objects as a result of scale change and thereby improve the legibility of the output image at the lower resolution. The scanned data is first supplied to a data sensitive thinner 5 which detects narrow gaps between adjacent objects and selectively detects image object edge pels in order to widen the gap. The selectively thinned scanned data is then supplied to a further thinner 6 which removes excess image pels from selected edges of the image objects. The data from thinner 6 is then supplied to a data sensitive merge inhibit unit 7 which moves selected image object pels from a subgroup in which merging as a result of scale change will occur to an adjacent subgroup where merging will not occur. Removal of a pel by the selective thinner 5, or by the thinner 6 or movement of a pel by unit 7 is inhibited if to do so would result in fragmentation of the associated image object.
A method for preserving continuities and discontinuities among clusters of the same first color valued pels originating in an m.times.n multicolor valued pel array upon said array being compressed into a smaller p.times.q size, at least two contiguous first color pels constituting a cluster, the method steps prior to compression include:
Data manipulation apparatus for receiving raster-scanned data as a first series of bits indicative of individual objects forming an image at a first picture element (pel) resolution and for converting the data into a second series of bits indicative of the image at a second lower pel resolution, comprising a scale changing means operable on receipt of said first series of input bits to convert selected subgroups of said input bits each into a single output bit, the significance of each output bit being determined by the presence or absence of a bit of a predetermined significance anywhere in the associated subgroup of input bits, the size of the subgroups being determined by the degree of compression required to effect the scale-change from said first to said second pel resolution, and means operable prior to scale-change for investigating bits in adjacent subgroups and selectively to change the significance of one or more of said investigated bits if merging of said objects after scale-change to said lower resolution would otherwise occur.
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
Scaling of whole images or parts thereof, e.g. expanding or contracting: based on decimating pixels or lines of pixels; based on inserting pixels…
Scaling of whole images or parts thereof, e.g. expanding or contracting: edge-driven scaling; Edge-based scaling
Using local operators: erosion or dilatation, e.g. thinning
Arrangements for image or video recognition or understanding: image preprocessing
Term ended 21 Sep 1999 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This invention relates to preserving connectivity or bifurcation among same colored pel clusters in a multicolored pel array undergoing electronic scale changing, and more particularly from a high to low order resolution scale change.
It has previously been proposed that documents could be scanned, digitized and stored electronically in a computer. The stored data could then be recalled from storage, reconstituted and either displayed on a display, printed with a printer/plotter, or transmitted over a data link for storage at another location. A document which is to be digitized can be scanned by a scanner whose output is a stream of bits which represent picture elements (pels) in successive lines of the raster scan. The resolution of a scanner is defined in terms of the number of pels per inch. Typical scanner output resolutions are 240, 120 and 96 pels/inch.
If during operation, a particular scanner produces an output in response to an input pel in the input image which is black over more than 50% say of the pel area but produces no output for pels with more than 50% white, then strokes in the input image which are thinner than 50% of the pel width will not be detected by the scanner resulting in stroke `dropout`. Furthermore, inter-stroke gaps of less than 50% pel width will also go undetected by the scanner resulting in stroke merging. Clearly, therefore, the higher the scanner resolution, the greater the potential legibility of the subsequently displayed image. The visual benefits provided by high resolution sampling, however, are offset by the corresponding rapid increase in the volume of data required to represent the image. This increase is proportional to the square of the increase in linear resolution. For an A4 size document (approximately 8 by 12 inches) over 3 million pels are required to represent the document at a scanning resolution of 240 pels per inch. The requirements for electronic storage of such scanned documents can become prohibitively expensive.
FIG. 1 shows in schematic form data manipulation or consolidation apparatus in accordance with the invention;
FIG. 2 shows an array of shift registers forming a part of consolidation apparatus and illustrates conceptually how a `slice` of image data is processed through the registers;
FIGS. 3, including A-D illustrates, shows the principle of operation of a scale change projector forming part of the consolidation apparatus;
FIG. 1 shows data consolidation apparatus in which image data on a document 1 is scanned at a high resolution by scanner 2, consolidated in consolidation unit 3, and thereafter displayed at a low resolution on display screen 4. The scanner 2 produces a series of bits at its output representing light and dark areas or pels on the scanned document at the scanner resolution. The consolidation unit 3 includes a data sensitive thinner 5 wherein bits are selectively removed from the raster scanned input bit pattern in an attempt to preserve the spacial structure of the original image when displayed at the lower resolution; a non-selective thinner 6 which removes further bits from the bit pattern to leave a processed or modified bit pattern in which the bits represent predominantly single pel-wide lines; a data sensitive merge inhibit unit 7 which repositions discrete bits to minimize residual merge states in the processed image; and finally a scale change projector 8 which effects the scale change from the high resolution input (say 240 pels/inch) to the low resolution output (say 96 pels/inch).
The data consolidation unit 3 operates synchronously from the serial bit raster output which is applied to input terminal 9 of an array of fourteen serially inter-connected shift registers SR1-SR14, shown in FIG. 2. Each shift register has a capacity equal to the total number of bits (approximately 1600) in a single raster line scan of the image. At any one time, therefore, the array of shift registers contains up to fourteen rows of image data. The three consolidation functions prior to scale change projection are continuously performed on a relatively small `slice` of image data (less than 50 bits wide) as it moves through the array of fourteen shift registers. The section of shift registers in which the `slice` of image data is processed is shown by chain-dotted box 10 in FIG. 2.
The upper part of FIG. 2 represents conceptually the situation wherein the image `slice` processed is in its initial position with respect to the shift registers with the first scan row of image data 11 contained in shift register SR1. The lower part of FIG. 2 represents the situation wherein the image `slice` is in its final position with the last scan row of the image data 11 contained in shift register SR14. The processed image bit stream emerging from output terminal 12 is ready for the scale change projection required in order to display at the lower resolution.