Graphic data redundancy reduction for text and half-tone optical facsimile system

Claim 2

A facsimile system for transmitting and receiving data representing black and white text and half-tone areas upon a document, comprising: means for optically scanning adjacent transverse areas of said document and converting each black and white and half-tone area within each scanned transverse area of said adjacent transverse areas of said document into digital signals; a plurality of memory means each storing said digital signals representing areas within one of said scannned transverse areas of said document; detector means for detecting the number of variations within said digital signals; selection means connected to said memory means to receive digital signals from more than one memory means and thereby more than one scanned adjacent transverse area at a time; said selection means including means for averaging said stored digital signals representing scanned adjacent transverse areaS of said document from said more than one memory means when said detected variations within said digital signals are few thereby areally compressing said stored digital signals for transmission and reception; said selection means further including means for alternately selecting between said stored digital signals representing said scanned adjacent transverse areas of said document from said more than one memory means when said detected variations within said digital signals are numerous thereby passing said digital signals for transmission and reception.

Claim 3

A facsimile system for transmitting and receiving data representing the contents of a document, comprising: means for space-by-space, line-by-line scanning of said document which converts the contents of said spaces and lines into digital data; memory means for storing said space-by-space digital data of each adjacent scan line; selection logic means; switching means for applying said stored, space-by-space digital data to said selection logic means such that digital data representing a selected number of spaces greater than one space and less than a full line of spaces from first one scan line and then digital data representing the same selected number of spaces from a selected number of adjacent scan lines is applied to said selection logic means; and said selection logic means including means for averaging a selected number of said stored, space-by-space digital data from a selected number of adjacent scan lines to compress said stored digital data into an area data signal representing a plurality of spaces.

Claim 4

A facsimile system for transmitting and receiving data representing the contents of a document, comprising: means for space-by-space, line-by-line scanning of said document which converts the contents of said spaces and lines into digital data; memory means for storing said space-by-space digital data of each adjacent scan line; selection logic means; switching means for applying said stored, space-by-space digital data to said selection logic means such that digital data representing a selected number of spaces greater than one space and less than a full line of spaces from first one scan line and then digital data representing the same selected number of spaces from a selected number of adjacent scan lines is applied to said selection logic means; and said selection logic means including means for averaging a selected number of said stored, space-by-space digital data from a selected number of adjacent scan lines to compress said stored digital data into an area data signal representing a plurality of spaces.

Claim 5

A facsimile system for transmitting and receiving data, as claimed in claim 2, additionally comprising: coding means for receiving a plurality of said area data signals each representing a plurality of spaces and converting identical consecutive area data signals into a binary code for further compressing said data to be transmitted and received.

Claim 6

A facsimile system for transmitting and receiving data, as claimed in claim 3, additionally comprising: detector means connected to said switching means for receiving said digital data and detecting the variations therein; said detector means connected to said selection logic means to enable said means for averaging of said digital data within said selection logic means when the variations between said digital data are few; and said detector means disabling said means for averaging of said digital data within said selection logic means when said variations between said digital data are numerous and instead applying said selected number of said stored, space-by-space digital data from said selected number of adjacent scan lines to said coding means.

Claim 7

A facsimile system for transmitting and receiving data, as claimed in claim 3, additionally comprising: gating means connecting said coding means to said switching means for applying said digital data stored within said memory means at a rate determined by said coding means, whereby the data transmitted by said facsimile system is at a constant rate.

Claim 8

A facsimile system for transmitting and receiving data, as claimed in claim 2, additionally comprising: said scanning means including adjustable optical means for line-by-line scanning of said document; means including switching means for transmitting said digital data representing space-by-space and line-by-line scanning of said document to said memory means; adjusting means connected between said means including switching means and said adjustable optical means for adjusting said optical means to scan the next adjacent scan line after said memory means has completed the storage of said digital data from the preceding scan line.

Claim 9

A facsimile system for transmitting and receiving data, as claimed in claim 6, additionally comprising: said scanning means further including a rotating drum upon which said document is mounted; said adjustable optical means including a Scanning head driven at a right angle to the rotation of said drum for coarse adjustment of said optical scan, and further including adjustable mirror means driven by an electrical input signal at a right angle to the rotation of said drum for fine adjustment of said optical scan; said adjusting means including a digital counter and digital to analog converter for generating said electrical input signal for driving said adjustable mirror means; said means including switching means connected to said digital counter for adjusting the count therein after each of said memory means is filled with digital data from one scan line for fine adjustment of said optical scan; gated drive means connected to said digital counter to drive said scanning head after said digital counter reaches a predetermined count for course adjustment of said optical scan; and feedback means for sensing said coarse adjustment of said scanning head connected to said digital counter to adjust said counter and thereby said fine adjustment of said optical scan, as said course adjustment is made.

Claim 10

A facsimile system for transmitting and receiving data representing the contents of a document, comprising: means for space-by-space, line-by-line scanning of said document including means for converting the contents thereof into digital data; first and second memory means; first switching means for applying said digital data to said first memory until all space-by-space digital data for one scan line is stored therein, and then for applying said digital data to said second memory until all space-by-space digital data for an adjacent scan line is stored therein; second switching means for reading said stored digital data first from said first memory means and then from said second memory means, such that digital data representing two spaces from one scan line and digital data representing two spaces from said adjacent scan line are presented; detector means for detecting variations between said digital data; selection means connected to said second switching means and said detector means for averaging said two and two digital data from said adjacent scan lines when said variations therebetween are few and, when said variations are numerous, for passing said digital data as presented from said second switching means without averaging wherein said data is compressed when said data is redundant.

Claim 11

A facsimile system for transmitting and receiving data representing the contents of a document, comprising: means for space-by-space, line-by-line scanning of said document including means for converting the contents thereof into digital data; first and second memory means; first switching means for applying said digital data to said first memory until all space-by-space digital data for one scan line is stored therein, and then for applying said digital data to said second memory until all space-by-space digital data for an adjacent scan line is stored therein; second switching means for reading said stored digital data first from said first memory means and then from said second memory means, such that digital data representing two spaces from one scan line and digital data representing two spaces from said adjacent scan line are presented; detector means for detecting variations between said digital data; selection means connected to said second switching means and said detector means for averaging said two and two digital data from said adjacent scan lines when said variations therebetween are few and, when said variations are numerous, for passing said digital data as presented from said second switching means without averaging wherein said data is compressed when said data is redundant.

Claim 12

A facsimile system for transmitting and receiving data, as claimed in claim 8, additionally comprising: coding means connected to said selection means for encoding said averaged digital data wherein further compression of said data is achieved when said data is redundant.

Claim 13

In a facsimile system for transmitting and receiving data contained on a document including means for line-by-line optical scanning of said document, means for converting each scan line into digital data, storage means for each scan line of digital data, and transmission means for transmitting said stored digital data; the improvement comprising: areal compression circuit means connected between said storage means and said transmission means for receiving stored digital data from more than one scan line at a time and areally compressing said stored digital data by averaging said digital data from more than one scan line at a time into a single unit of digital data for transmission; variation detector means within said areal compression circuit means connected to said storage means for detecting variations in said stored digital data; counter means for counting a selected number of single units of stored digital data connected to said storage means; clock means for generating timing pulses connected to said counter means; means for dividing said timing pulses by a value equal to said selected number of single units of stored digital data connected to said counter means to reset said counter; delay means connected to said storage means for delaying said stOred digital data therefrom by said selected number of single units of stored digital data; decoder means connected to said counter means for receiving an output count therefrom and generating an output signal when the received count from said counter means is greater than one-half of said selected number of single units of stored digital data; single unit storage means connected to said decoder means to store the output signal generated by said decoder means and further connected to apply the last received output signal from said decoder means back to said decoder means for changing the output signal therefrom when the received count from said counter means is equal to one-half of said selected number of single units of stored digital data; data selection means connected to said variation detector means, said delay means, and said single unit storage means for passing a single unit of digital data from said single unit storage means for transmission if said detector means detects a few variations in said stored digital data and for passing a selected number of single units of stored digital data for transmission if said detector means detects numerous variations in said stored digital data.

Claim 14

In a facsimile system for transmitting and receiving data contained on a document including means for line-by-line optical scanning of said document, means for converting each scan line into digital data, storage means for each scan line of digital data, and transmission means for transmitting said stored digital data; the improvement comprising: areal compression circuit means connected between said storage means and said transmission means for receiving stored digital data from more than one scan line at a time and areally compressing said stored digital data by averaging said digital data from more than one scan line at a time into a single unit of digital data for transmission; variation detector means within said areal compression circuit means connected to said storage means for detecting variations in said stored digital data; counter means for counting a selected number of single units of stored digital data connected to said storage means; clock means for generating timing pulses connected to said counter means; means for dividing said timing pulses by a value equal to said selected number of single units of stored digital data connected to said counter means to reset said counter; delay means connected to said storage means for delaying said stOred digital data therefrom by said selected number of single units of stored digital data; decoder means connected to said counter means for receiving an output count therefrom and generating an output signal when the received count from said counter means is greater than one-half of said selected number of single units of stored digital data; single unit storage means connected to said decoder means to store the output signal generated by said decoder means and further connected to apply the last received output signal from said decoder means back to said decoder means for changing the output signal therefrom when the received count from said counter means is equal to one-half of said selected number of single units of stored digital data; data selection means connected to said variation detector means, said delay means, and said single unit storage means for passing a single unit of digital data from said single unit storage means for transmission if said detector means detects a few variations in said stored digital data and for passing a selected number of single units of stored digital data for transmission if said detector means detects numerous variations in said stored digital data.

Claim 15

A facsimile system for transmitting and receiving data representing the contents of a document, comprising: means for line-by-line scanning of said document including means for converting segments of each scan line into digital data; clock means for generating clock pulses; switching means; transition detector means connected to said clock means and said switching means for receiving said digital data from said means for scanning under control of said clock means; first and second counter means; said transition detector means connected to said first and second counter means for applying said clock pulses to said first and then said second counter means until a change is detected in said received digital data for stopping said application of clock pulses to said counters; output register means connected to said first and second counter means for generating an output signal in the form of a binary word representing the count stored in said first and second counters to be transmitted from said facsimile system; overflow detector means connected between said first and second counter means for enabling said first counter means and disabling said second counter means until said first counter is filled and then for disabling said first counter and enabling said second counter, whereby said binary word generated by said output register means from said first counter represents the count therein and said binary word generated from said second counter represents a remainder of said count in said first counter.

Claim 16

A facsimile system for transmitting and receiving data representing the contents of a document, comprising: means for line-by-line scanning of said document including means for converting segments of each scan line into digital data; clock means for generating clock pulses; switching means; transition detector means connected to said clock means and said switching means for receiving said digital data from said means for scanning under control of said clock means; first and second counter means; said transition detector means connected to said first and second counter means for applying said clock pulses to said first and then said second counter means until a change is detected in said received digital data for stopping said application of clock pulses to said counters; output register means connected to said first and second counter means for generating an output signal in the form of a binary word representing the count stored in said first and second counters to be transmitted from said facsimile system; overflow detector means connected between said first and second counter means for enabling said first counter means and disabling said second counter means until said first counter is filled and then for disabling said first counter and enabling said second counter, whereby said binary word generated by said output register means from said first counter represents the count therein and said binary word generated from said second counter represents a remainder of said count in said first counter.