Printing system and method

Abstract

A image is printed from a source of drawing instructions. The image is reducible to pixels arranged in a plurality of ranked image lines. The system employs a storage device having compressed and uncompressed regions. Each region has a designated capacity and each is arranged to store pixels of one or more of the plurality of image lines. A drawing processor is coupled to the storage device and can be coupled to the source of drawing instructions for responding thereto. This drawing processor can store new pixels in the storage device for successively selected ones of the image lines. The drawing processor has a conditional device, a decompression device and an insertion device. The conditional device can compressively encode and move from the uncompressed region to the compressed region, a remote one of the image lines, if: a) the selected one of the image lines is in the compressed region, and b) the uncompressed region has reached its designated capacity. The decompression device can expansively decode the selected one of the image lines, if located in the compressed region. The insertion device can insert one or more new pixels according to the drawing instructions into the selected one of the image lines by storing the selected one in the uncompressed region. The printing system also has a printing engine coupled to the storage device for printing the plurality of image lines in rank order, decompressing compressed ones of the image lines from the compressed region before printing.

1. A printing system for printing from a source of drawing instructions a two dimensional image reducible to pixels arranged in a plurality of ranked image lines, comprising:
 a storage means having a compressed region and an uncompressed region, each having a designated capacity and each being arranged to store pixels of one or more of said plurality of image lines;    drawing means coupled to said storage means and adapted to be coupled to said source of drawing instructions for responding thereto, said drawing means being operable to store new pixels in said storage means for successively selected ones of said image lines, said drawing means including:    (a) conditional means for compressively encoding and moving from said uncompressed region to said compressed region a remote one of said image lines, if (i) the selected one of said image lines is in said compressed region and (ii) said uncompressed region has reached its designated capacity;    (b) decompression means for expansively decoding said selected one of said image lines, if located in said compressed region; and    (c) insertion means for inserting one or more new pixels according to said drawing instructions into said selected one of said image lines by storing said selected one in said uncompressed region; and    printing means coupled to said storage means for printing said plurality of image lines in rank order, decompressing compressed ones of said image lines from said compressed region before printing.    
     
     
       2. A printing system according to  claim 1  wherein said drawing means is operable to store in the storage means pixels associated with a full page worth of the instructions, said printing means being operable to await the storage in said storage means of said full page worth of said pixels before printing the image lines of said page. 
     
     
       3. A printing system according to  claim 2  wherein said decompression means is operable to compressively encode and move from said uncompressed region to said compressed region said remote one of said image lines together with a plurality of other ones of said image lines proximate said remote one, so that lines are moved in groups. 
     
     
       4. A printing system according to  claim 3  wherein said decompression means is operable to expansively decode and move from said compressed region to said uncompressed region said selected one of said image lines together with a plurality of other ones of said image lines proximate said remote one, so that lines are moved in groups. 
     
     
       5. A printing system according to  claim 2  wherein said drawing means is operable to successively decompose one or more of the instructions from said source of drawing instructions into a list of simpler directions and store said list in said storage means, said drawing means being operable to numerically limit the instructions to keep said list within a designated size. 
     
     
       6. A printing system according to  claim 5  wherein said two dimensional image comprises a plurality of contiguous bands and each of the image lines is allocated to a corresponding one of said bands, said drawing means being operable to scan the bands and restrict selection of said image lines to those allocated to a current one of said bands, said drawing means being operable to cyclically execute the directions of said list with a scope limited to storing pixels in the storage means for the image lines contained within the current one of said bands. 
     
     
       7. A printing system according to  claim 6  wherein said drawing means is operable to overwrite the list of directions by decomposing and storing in said storage means unused ones of the instructions from said source of drawing instructions, said drawing means being operable to rescan the bands and restrict selection of said image lines to those allocated to a current one of said bands, said drawing means being operable to again cyclically execute the latest ones of the directions with a scope limited to storing pixels in the storage means for the image lines contained within the current one of said bands. 
     
     
       8. A printing system according to  claim 7  wherein said conditional means is operable to compressively encode said image lines at a chosen one of a plurality of encoding densities and is operable to move said image lines to said compressed region with a compression code signifying said chosen one of said encoding densities. 
     
     
       9. A printing system according to  claim 8  comprising:
 means for determining at least one of the characteristics of the image, said drawing means being operable to select said chosen one of said densities in response to said one of the characteristics of said image.    
     
     
       10. A printing system according to  claim 8  wherein said storage means has a printing region, said printing means being operable to expansively decode said image lines in rank order and store them in said printing region. 
     
     
       11. A printing system according to  claim 8  wherein said decompression means is operable to store said selected one of said image lines after decompression in said uncompressed region with an uncompressed code signifying a lack of compression, said printing means being operable to store said image lines in said printing region without a code signifying a lack of compression. 
     
     
       12. A printing system according to  claim 8  wherein said storage means is volatile and has a total capacity insufficient to hold all of said image lines uncompressed, the densest one of said encoding densities having the capability of reducing the resolution of the two dimensional image and storing it at a density that enables storage in said storage means of all of said image lines, without regard to the number and arrangement of pixels in said image lines, so that nonvolatile memory is unneeded for storing said image lines. 
     
     
       13. A printing system according to  claim 8  wherein said decompression means is operable to sense the compression code and in response thereto expansively decode said selected one of said image lines with respect to said chosen one of said encoding densities. 
     
     
       14. A printing system according to  claim 13  wherein said conditional means is operable if said compressed region has reached its designated capacity to compressively re-encode at least some of the image lines in said compressed region at a denser one of said densities. 
     
     
       15. A printing system according to  claim 13  further comprising a non-volatile memory coupled to said drawing means, said conditional means being operable to move at least some of the image lines in said compressed region to said non-volatile memory, if said compressed region has reached its designated capacity and the image lines in said compressed region are encoded at the densest permissible one of said densities. 
     
     
       16. A printing system according to  claim 13  further comprising a non-volatile memory coupled to said drawing means, said conditional means being operable to move at least some of the image lines in said compressed region to said non-volatile memory, if said compressed region has reached its designated capacity. 
     
     
       17. A printing system according to  claim 16  wherein said decompression means is operable to expansively decode said selected one of said image lines, if located in said non-volatile memory. 
     
     
       18. A printing system according to  claim 2  wherein said drawing means is operable to change the ratio of the capacities of said compressed and said uncompressed regions by redesignating portions of one in favor of the other in response to the availability of storage space in one or more of the regions of said storage means. 
     
     
       19. A printing system according to  claim 2  wherein said conditional means is operable to compressively encode said image lines at a chosen one of a plurality of encoding densities and is operable to move said image lines to said compressed region with a compression code signifying said chosen one of said encoding densities, said drawing means being operable to change the ratio of the capacities of said compressed and said uncompressed regions by redesignating portions of one in favor of the other in response to the choosing of the chosen one of said encoding densities. 
     
     
       20. A printing system according to  claim 2  wherein said drawing means is operable to change the ratio of the capacities of said compressed and said uncompressed regions by redesignating portions of one in favor of the other in response to the size of page to be printed by said printing means. 
     
     
       21. A printing system according to  claim 1  wherein said source of drawing instructions comprises a computer assembly having a processor and a computer memory spaced and packaged separately from said storage means, said drawing means and said printing means. 
     
     
       22. A printing system according to  claim 21  further comprising:
 a printer casing containing said storage means, said drawing means and said printing means.    
     
     
       23. A printing system according to  claim 6  wherein said source of drawing instructions comprises a computer assembly having a processor and a computer memory spaced and packaged separately from said storage means, said drawing means and said printing means. 
     
     
       24. A printing system according to  claim 1  wherein said source of drawing instructions includes a computer assembly having a processor and a computer memory spaced and packaged separately from said printing means, said printing system further comprising:
 a frame attached to said computer assembly for supporting said drawing means and said storage means.    
     
     
       25. A printing system according to  claim 24  wherein said drawing means is operable to successively decompose one or more of the instructions from said source of drawing instructions into a list of simpler directions and store said list in said storage means, said drawing means being operable to numerically limit the instructions to keep said list within a designated size. 
     
     
       26. A printing system according to  claim 25  wherein said two dimensional image comprises a plurality of contiguous bands and each of the image lines is allocated to a corresponding one of said bands, said drawing means being operable to scan the bands and restrict selection of said image lines to those allocated to a current one of said bands, said drawing means being operable to cyclically execute the directions of said list with a scope limited to storing pixels in the storage means for the image lines contained within the current one of said bands. 
     
     
       27. A printing method employing a storage means having a compressed region and an uncompressed region for printing from a source of drawing instructions a two dimensional image reducible to pixels arranged in a plurality of ranked image lines, comprising the steps of:
 storing new pixels in said storage means for successively selected ones of said image lines by:    (a) compressively encoding and moving from said uncompressed region to said compressed region a remote one of said image lines, if (i) the selected one of said image lines is in said compressed region and (ii) said uncompressed region has reached its capacity;    (b) expansively decoding said selected one of said image lines, if located in said compressed region; and    (c) inserting one or more new pixels according to said drawing instructions into said selected one of said image lines by storing said selected one in said uncompressed region; and    printing said plurality of image lines in rank order, decompressing compressed ones of said image lines from said compressed region before printing.    
     
     
       28. A printing method according to  claim 27  wherein the step of storing new pixels comprises the steps of:
 successively decomposing one or more of the instructions from said source of drawing instructions into a list of simpler directions, while numerically limiting the instructions to keep said list within a designated size; and    saving said list in said storage means.    
     
     
       29. A printing method according to  claim 28  wherein said two dimensional image comprises a plurality of contiguous bands and each of the image lines is allocated to a corresponding one of said bands, the step of storing new pixels comprises the steps of:
 scanning the bands and restricting selection of said image lines to those allocated to a current one of said bands; and    cyclically executing the directions of said list with a scope limited to storing pixels in the storage means for the image lines contained within the current one of said bands.    
     
     
       30. A printing method according to  claim 29  comprising the steps of:
 overwriting the list of directions by decomposing and storing in said storage means unused ones of the instructions from said source of drawing instructions;    rescanning the bands and restricting selection of said image lines to those allocated to a current one of said bands; and    again cyclically executing the latest ones of the directions with a scope limited to storing pixels in the storage means for the image lines contained within the current one of said bands.    
     
     
       31. A printing method according to  claim 30  comprising the steps of:
 compressively encoding said image lines at a chosen one of a plurality of encoding densities; and    storing said image lines in said compressed region with a compression code signifying said chosen one of said encoding densities.    
     
     
       32. A printing method according to  claim 31  comprising the step of:
 sensing the compression code and in response thereto expansively decoding said selected one of said image lines with respect to said chosen one of said encoding densities.    
     
     
       33. A printing method according to  claim 32  comprising the step of:
 compressively re-encoding at least some of the image lines in said compressed region at a denser one of said densities, if said compressed region has reached its capacity.    
     
     
       34. A printing method according to  claim 31  comprising the step of:
 determining at least one of the characteristics of the image, said chosen one of said densities being selected in dependence upon said one of the characteristics of said image.    
     
     
       35. A printing method according to  claim 31  wherein the step of storing said selected one of said image lines after decompression in said compressed region is performed by storing said selected one with an uncompressed code signifying a lack of compression, the step of printing being performed by storing said image lines in said storage means without a code signifying a lack of compression. 
     
     
       36. A printing method according to  claim 31  wherein said storage means is volatile and has a total capacity insufficient to hold all of said image lines uncompressed, the densest one of said encoding densities having the capability of reducing the resolution of the two dimensional image and storing it at a density that enables storage in said storage means of all of said image lines, without regard to the number and arrangement of pixels in said image lines, so that nonvolatile memory is unneeded for storing said image lines. 
     
     
       37. A printing method according to  claim 27  wherein the step of compressively encoding and moving is performed by encoding and moving from said uncompressed region to said compressed region said remote one of said image lines together with a plurality of other ones of said image lines, so that lines are moved in groups. 
     
     
       38. A printing method according to  claim 37  wherein the step of expansively decoding is performed by decoding and moving from said compressed region to said uncompressed region said selected one of said image lines together with a plurality of other ones of said image lines, so that lines are moved in groups. 
     
     
       39. A printing method according to  claim 27  further comprising the step of
 changing the ratio of the capacities of said compressed and said uncompressed regions by redesignating portions of one in favor of the other in response to the availability of storage space in one or more of the regions of said storage means.    
     
     
       40. A printing method according to  claim 27  further comprising the steps of:
 compressively encoding said image lines at a chosen one of a plurality of encoding densities; and    moving said image lines to said compressed region with a compression code signifying said chosen one of said encoding densities; and    changing the ratio of the capacities of said compressed and said uncompressed regions by redesignating portions of one in favor of the other in response to the choosing of the chosen one of said encoding densities.    
     
     
       41. A printing method according to  claim 27  further comprising the step of:
 changing the ratio of the capacities of said compressed and said uncompressed regions by redesignating portions of one in favor of the other in dependence upon the size of page to be printed.    
     
     
       42. A printing system for printing a two dimensional image comprising:
   a memory having a compressed region and an uncompressed region and each region being arranged to store discrete portions of said image;        drawing means coupled to said memory, said drawing means being operable to store said discrete image portions in said memory, said drawing means including:      ( a )  conditional means for compressively encoding and moving discrete image portions from said uncompressed region to said compressed region;      ( b )  decompression means for expansively decoding discrete image portions, if located in said compressed region; and      ( c )  insertion means for inserting one or more discrete image portions into said image by storing a selected discrete image portion in said uncompressed region; and        printing means coupled to said memory for decompressing compressed ones of said discrete portions from said compressed region before printing.     
     
     
       43. A printing method employing a memory having a compressed region and an uncompressed region for printing a two dimensional image, the method comprising:
   storing discrete portions of said image in said storage by:      ( a )  compressively encoding and moving from said uncompressed region to said compressed region at least one of said discrete image portions;      ( b )  expansively decoding a selected one of said discrete image portions, if located in said compressed region; and      ( c )  inserting one or more discrete image portions into said image by storing a selected discrete image portion in said uncompressed region; and        decompressing compressed ones of said discrete image portions from said compressed region before printing.