Encoding/decoding system with two-stages of encoding/decoding
AssigneeComsat Corporation
InventorsFranklin L. Corcoran, Spiros Dimolitsas
Life of this patent
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Abstract
A compression and decompression system for transmitting facsimile images in which the facsimile image is compressed in a vertical and a horizontal direction. The compressed facsimile image is decompressed by selecting a reference bit in the decompressed facsimile image and expanding the bit in a vertical and a horizontal direction in accordance with a binary value of bits near the selected reference bit.
Claims9
An encoding system for compressing an original facsimile image, comprising:
- a first encoder, coupled to receive the facsimile image, for vertically compressing the original facsimile image, thereby providing a first vertically-compressed facsimile image;
- and
- a second encoder, coupled to receive an output of said first encoder, for vertically compressing the first vertically-compressed facsimile image from said first encoder, thereby providing a second vertically-compressed facsimile image;
- said first encoder vertically compressing the original facsimile image by selectively retaining scan lines thereof, and said second encoder vertically compressing the first vertically-compressed facsimile image provided by said first encoder by performing a logical OR operation on pairs of scan lines of the first vertically-compressed facsimile image.
A method of encoding an original facsimile image, comprising the steps of:
- a first step of vertically compressing the original facsimile image by selectively retaining scan lines thereof, thereby providing a first vertically-compressed facsimile image;
- and
- a second step of vertically compressing the first vertically-compressed facsimile image by performing a logical OR operation on pairs of scan lines of the first vertically-compressed facsimile image, thereby providing a second vertically-compressed facsimile image.
A system for decoding an encoded facsimile image comprising:
- a first decoder, coupled to receive the encoded facsimile image;
- and
- a second decoder, coupled to receive an output of said first decoder;
- said first decoder decoding the encoded facsimile image by selecting a bit in the encoded facsimile image as a first reference bit, and horizontally expanding said first reference bit with a predetermined bit pattern in accordance with bit values near said reference bit, said second decoder decoding the facsimile image output from said first decoder by selecting a second reference bit therein, and vertically expanding said second reference bit with a predetermined bit pattern in accordance with bit values near said second second reference bit.
Dependencies are inferred from the claim text.