Intelligent doubling for low-cost image buffers
First Claim
1. A method of encoding a graphic image at full resolution for storing in a reduced image buffer for subsequent decoding and printing by a marking device, the method comprising the steps of:
- segmenting said graphic image into blocks;
distinguishing smooth areas of the image from edges of the image;
determining a construction of the edges in a block of the image blocks, said determining step comprising describing an edge for the block by storing positions at which the edge enters and exits the block;
assigning reference points around the entire perimeter of the block relative to a given point; and
storing the construction, encoded as the entry and exit points of the edge measured in terms of said reference points in the reduced image buffer.
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Accused Products
Abstract
A method and apparatus for achieving an ultra-small or compressed image buffer images at half the resolution and then scales by two to achieve the device resolution. Acceptable quality can be maintained by identifying edge and interior portions of the page image and using this information to scale intelligently. A split-level frame buffer provides this identification of the image components. Further, an extension of block-truncation coding can be used with the split-level frame buffer to provide up to a 16 to 1 compression for an overall compression of up to 64 to 1. Actual techniques to scale these encodings are described along with new encodings for graphics and text designed this high compression of the image.
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Citations
30 Claims
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1. A method of encoding a graphic image at full resolution for storing in a reduced image buffer for subsequent decoding and printing by a marking device, the method comprising the steps of:
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segmenting said graphic image into blocks; distinguishing smooth areas of the image from edges of the image; determining a construction of the edges in a block of the image blocks, said determining step comprising describing an edge for the block by storing positions at which the edge enters and exits the block; assigning reference points around the entire perimeter of the block relative to a given point; and storing the construction, encoded as the entry and exit points of the edge measured in terms of said reference points in the reduced image buffer. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for encoding a graphic image at full resolution for storing in a reduced image buffer for subsequent decoding and printing by a marking device, the apparatus comprising:
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means for segmenting said graphic image into blocks; means for distinguishing smooth areas of the image from edges of the image; means for determining a construction of the edges in a block of the image blocks, said determining means comprising means for describing an edge for the block by storing positions at which the edge enters and exits the block; means for assigning reference points around the entire perimeter of the block relative to a given point; and means for storing the construction, encoded as the entry and exit points of the edge measured in terms of said reference points, in the reduced image buffer. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method of encoding and decoding a continuous tone image having a plurality of image region types, in a reduced image buffer with a uniform a block structure for printing by a marking device, wherein the image region types comprise pictorial and nonpictorial image region types and the nonpictorial image region types comprise at least one of text region types and graphic and line region types, the method comprising the steps of:
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identifying edge regions and non-edge regions of said continuous tone image; distinguishing between pictorial region types and non-pictorial region types; encoding said continuous tone image according to said identifying step, by using different encoding methods for said edge regions, and said non-edge regions; encoding pictorial region types at half a required resolution for the marking device; storing said encoded continuous tone image in said reduced image buffer; decoding said stored encoded continuous tone image in accordance with said identifying step that identifies edge regions; and doubling said pictorial region types, wherein said pictorial region types are decoded and doubled by the steps of, distinguishing smooth areas of the pictorial region types from edges of the pictorial region types; resolution doubling said smooth areas by a first resolution doubling technique; and resolution doubling said edges by a second resolution doubling technique, said second resolution doubling technique being different from said first resolution doubling technique. - View Dependent Claims (14)
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15. An apparatus for encoding and decoding a continuous tone image having a plurality of image region types, in a reduced image buffer with a uniform block structure for printing by marking a device, wherein the image region types comprise pictorial and nonpictorial image region types and the nonpictorial image region types comprise at least one of text region types and graphic and line region types, the apparatus comprising:
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means for identifying edge regions and non-edge regions of said continuous tone image; means for distinguishing between pictorial region types and non-pictorial region types; means for encoding said continuous tone image according to identification of said edge regions and said non-edge regions; means for encoding pictorial region types at half a required resolution for the marking device; means for storing said encoded continuous tone image in said reduced image buffer; means for decoding said stored encoded continuous tone image in accordance with said identifying means that identifies edge regions; and means for doubling said pictorial region types, wherein said means for decoding and doubling pictorial region types comprises, means for distinguishing smooth areas of the image from edges of the image; means for resolution doubling said smooth areas by a first resolution doubling technique; and means for resolution doubling said edges by a second resolution doubling technique, said second resolution doubling technique being different from said first resolution doubling technique. - View Dependent Claims (16)
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17. A method of encoding and decoding a continuous tone image, having a plurality of image region types, in a a reduced image buffer with a uniform a block structure for printing by a marking device, wherein the image region types comprise pictorial and nonpictorial image region types and the nonpictorial image region types comprise at least one of text region types and graphic and line region types, the method comprising the steps of:
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identifying edge regions and non-edge regions of said continuous tone image; distinguishing between pictorial region types and non-pictorial region types; encoding said continuous tone image according to said identifying step, by using different encoding methods for said edge regions, and said non-edge regions; encoding pictorial region types at half a required resolution for the marking device; storing said encoded continuous tone image in said reduced image buffer; decoding said stored encoded continuous tone image in accordance with said identifying step that identifies edge regions; and doubling said pictorial region types, wherein said graphic and line region types are encoded by the steps of, segmenting said image into blocks; distinguishing edge regions and non-edge regions of said graphic and line region types; determining a construction of the edges in a block of the image blocks; and storing the construction in the reduced image buffer. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. An apparatus for encoding and decoding a continuous tone image having a plurality of image region types, in a reduced image buffer with a uniform block structure for printing by marking a device, wherein the image region types comprise pictorial and nonpictorial image region types and the nonpictorial image region types comprise at least one of text region types and graphic and line region types, the apparatus comprising:
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means for identifying edge regions and non-edge regions of said continuous tone image; means for distinguishing between pictorial region types and non-pictorial region types; means for encoding said continuous tone image according to identification of said edge regions and said non-edge regions; means for encoding pictorial region types at half a required resolution for the marking device; means for storing said encoded continuous tone image in said reduced image buffer; means for decoding said stored encoded continuous tone image in accordance with said identifying means that identifies edge regions; and means for doubling said pictorial region types, wherein said means for encoding said graphic and line region types comprises, means for segmenting said image into blocks; means for distinguishing edge regions and non-edge regions of said graphic and line region types; means for determining a construction of the edges in a block of the image blocks; and means for storing the construction in the reduced image buffer. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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Specification