Printer control unit and method

• US 5,737,501 A
• Filed: 07/09/1996
• Issued: 04/07/1998
• Est. Priority Date: 07/14/1995
• Status: Expired due to Term

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Tsunekawa, Kiyohiro
• Primary Examiner(s): Evans, Arthur G.
• Application Number:
  US08/677,108
• Time in Patent Office: 637 Days
• Field of Search: 395/102, 395/101, 395/110, 395/112, 395/114, 395/128, 395/139, 395/133, 395/167, 395/168, 395/170, 395/171, 395/172, 358/470, 358/451, 382/233, 382/185, 345/25-26, 345/127-130, 345/132, 345/141-143, 345/192, 345/194-195, 400/61-63, 400/67, 400/70
• US Class Current: 358/1.2
• CPC Class Codes: G06K 15/02 using printers
• CPC Class Codes: G06K 2215/0028 characterised by the format per se
• CPC Class Codes: G06K 2215/0054 Geometric transformations, e.g. on rasterised data

Abstract

When there occurs a need to perform resolution conversion while a drawing object, such as a character, is formed, deterioration of print quality is reduced by selecting a reforming method according to the type of font. The quality of other pages is prevented from deteriorating in a case in which a drawing object is referenced at the same time from different pages by forming another drawing object. Prevention of deterioration of quality is achieved by selecting a method of forming (for example, by rescaling when the font is scalable) a pattern having a different resolution according to the type of font in a case in which a drawing object is formed on the basis of print data. Further, prevention of deterioration of quality is achieved where a drawing object is shared among a plurality of pages by forming another drawing object when a decreased resolution is desired.

Claims

1. A printer control unit, comprising:

drawing object forming means for forming a drawing object described in an intermediate data format on the basis of input print data; and

selection means for selecting font object forming means according to a font type of a reference drawing object which is a font object when there occurs a need to form an image at a resolution different from the resolution at which the reference drawing object was formed.

2. A printer control unit according to claim 1, wherein said selection means selects font object forming means for forming a font object having a resolution which is different than the resolution of the reference drawing object by performing a thinning-out operation on dot font data when the font type of said reference drawing object is a dot font, and wherein said selection means selects font object forming means for forming a font object having a resolution which is different than the resolution of the reference drawing object by performing rescaling using scalable font data when the font type of said reference drawing object is a scalable font.

3. A printer control unit according to claim 1, further comprising:

storage means for storing at least one of scalable font data and dot font data input into said printer control unit; and

deleting means for deleting font data stored by said storage means, wherein said selection means makes a determination as to whether said font data has already been deleted when said font data is scalable font data, selects font object forming means for forming a font object by thinning out a font pattern generated on the basis of said scalable font data when said scalable font data has been deleted and for forming a font object by performing rescaling on the basis of said scalable font data when said scalable font data has not been deleted, and selects font object forming means for forming a font object by performing a thinning-out operation when said font is dot font data.

4. A printer control unit according to claim 1, further comprising:

input content identification means for identifying contents of input print data having the same character type and the same character code as a pre-formed font object formed from previously input font data, wherein said selection means selects forming means for forming a font object having a resolution which is different than the resolution of the pre-formed font object by thinning out a font pattern without performing rescaling when it is determined by said input content identification means that the input print data have a content which is different than a content of the pre-formed font object in a case in which the pre-formed font object includes a font pattern generated on the basis of previously input scalable font data.

5. A printer control unit according to claim 1, further comprising dot pattern storage means for storing font information in a dot pattern format, wherein said selection means selects font object forming means for forming a font object by using a dot pattern stored in said dot pattern storage means without thinning out a font pattern when a dot font expansion ratio and a resolution conversion ratio combination results in an effective expansion ratio of 1.

6. A printer control unit according to claim 1, further comprising image forming means, wherein said image forming means forms said image at a resolution different from that at which the reference drawing object was formed in a case in which an amount of memory necessary for storing drawing objects on a page on which said image is to be formed is larger than a fixed amount, or in a case in which it is determined that there is an overrun band in the page for which the time required to develop drawing objects onto the overrun band is longer than a time required to output an image in a band to outside.

7. A printer control unit according to claim 1, further comprising:

forming means for forming image data on the basis of said drawing object; and

printing means for performing printing on the basis of the image data formed by said forming means.

8. A printer control unit according to claim 7, wherein said printing means is a page printer.

21. A printer control unit according to claim 1, wherein said reference drawing object is referenced from a plurality of pages.

9. A printer control unit for drawing an image by retrieving a previously formed font object corresponding to previously input print data when a same character type and the same character code as those of the previously formed font object are requested in current print data and by referring to said previously formed font object when said previously formed font object is present, said printer control unit comprising:

determination means for determining if previously formed font object is referenced from another page when there occurs a need to form an image at a resolution different from a resolution at the previously formed font object was formed; and

forming means for forming a font object different from said previously formed font object when it is determined by said determination means that said previously formed font object is referenced from another page.

10. A printer control unit according to claim 9, further comprising both-sides printing means capable of printing on both sides of a recording medium.

22. A printer control unit according to claim 9, wherein said previously formed font object is referenced from a plurality of pages.

11. A printer control method, comprising:

a drawing object forming step of forming a drawing object described in an intermediate data format on the basis of input print data; and

a selection step of selecting a font object forming step according to a font type of a reference drawing object which is a font object in a case in which there occurs a need to form an image at a resolution different from that at which the reference drawing object was formed.

12. A printer control method according to claim 11, wherein said selection step selects a font object forming step of forming a font object having a resolution which is different than the resolution of the reference drawing object by performing a thinning-out operation on dot font data when the font type of said reference drawing object is a dot font, and said selection step selects a font object forming step of forming a font object having a resolution which is different than the resolution of the reference drawing object by performing rescaling using scalable font data when the font type of said reference drawing object is a scalable font.

13. A printer control method according to claim 11, further comprising:

a storage step of storing at least one of scalable font data and dot font data input; and

a deleting step of deleting font data, wherein said selection step makes a determination as to whether said font data has already been deleted when said font data is scalable font data, selects a font object forming step of forming a font object by thinning out a font pattern formed on the basis of said scalable font data when said scalable font data has been deleted and forming a font object by performing rescaling on the basis of said scalable font data when said scalable font data has not been deleted, and selects a font object forming step of forming a font object by performing a thinning-out operation when said font data is dot font data.

14. A printer control method according to claim 11, further comprising:

an input content identifying step of identifying contents of input print data having the same character type and the same character code as a pre-formed font object formed from previously input font data, wherein said selection step selects a font object forming step of forming a font object having a resolution which is different than the resolution of the pre-formed font object by thinning out a font pattern without performing rescaling when it is determined by said input content identification step that the input print data have a font of a content which is different than a content of the pre-formed font object in a case in which the pre-formed font object includes a font pattern formed on the basis of previously input scalable font data.

15. A printer control method according to claim 11, comprising:

a dot font storage step of storing font information in a dot pattern format, wherein said selection step selects a font object forming step of forming a font object by using a dot pattern stored by said dot font storage step without thinning out a font pattern when a dot font expansion ratio and a resolution conversion ratio combination results in an effective expansion ratio of 1.

16. A printer control method according to claim 11, further comprising an image forming step, wherein said image forming step forms said image at a resolution different from that at which the reference drawing object was formed in a case in which an amount of memory necessary for storing drawing objects on a page on which said image is to be formed is larger than a fixed amount, or in a case in which it is determined that there is an overrun in the band, for which the time required to develop drawing objects onto the overrun band is longer than a time required to output an image in a band.

17. A printer control method according to claim 11, further comprising:

a forming step of forming image data on the basis of said drawing object; and

a printing step of printing the image data formed in said forming step by means of printing means.

18. A printer control method according to claim 17, wherein said printing means is a page printer.

23. A printer control method according to claim 11, wherein said reference drawing object is referenced from a plurality of pages.

19. A printer control method for retrieving a previously formed font object corresponding to print data input earlier and for drawing an image by referring to said previously formed font object when said font object is present in a case in which a same character type and same character code as those of the previously formed font object are requested in current print data, said printer control method comprising:

a determination step of determining if the previously formed font object is referenced from another page when there occurs a need to form an image at a resolution different from a resolution at which the previously formed font object was formed; and

a forming step of forming a font object different from said previously formed font object when it is determined by said determination step that the previously formed font object is referenced from another page.

20. A printer control method according to claim 19, further comprising a both-sides printing step for performing printing on both sides of a recording medium.

24. A printer control method according to claim 19, wherein said previously formed font object is referenced from a plurality of pages.

25. A memory which is accessed by a computer, said memory having stored therein the following programs:

a drawing object forming program for forming a drawing object described in an intermediate data format on the basis of input print data; and

a selection program for selecting a font object forming program according to a font type of a reference drawing object which is a font object in a case in which there occurs a need to form an image at a resolution different from that at which the reference drawing object was formed.

26. A memory which is accessed by a computer, said memory having stored therein a printer control program for retrieving a previously formed font object corresponding to previously input print data and for drawing an image by referring to said previously formed font object when said previously formed font object is present in a case in which a same character type and same character code as those of the previously formed font object are requested in current print data, said printer control program including:

a determination program for determining whether the previously formed font object is referenced from another page when there occurs a need to form an image at a resolution different from a resolution at which the previously formed font object was formed; and

a forming program for forming a font object different from said previously formed font object when it is determined by said determination program that the previously formed font object is referenced from another page.

27. A method for re-writing font objects at a reduced resolution, said method comprising:

inspecting each font object to determine if such font object is a scalable font object or a non-scalable font object;

re-writing each scalable font object by re-reading font information pertaining to the font object and using the font information to form a new font object at the reduced resolution from font data from which such scalable font object was formed; and

re-writing each non-scalable font object by thinning out such non-scalable font object to the reduced resolution.

28. A method for re-writing font objects at a reduced resolution, said method comprising:

inspecting each font object to determine if such font object is a rescalable font object or a non-rescalable font object, with a rescalable font object being a scalable font object for which font data from which such scalable font object was formed has not been deleted or changed, and a non-rescalable font object being a font object which is not a rescalable font object;

re-writing each rescalable font object by re-reading font information pertaining to such rescalable font object and using the font information to form a new font object at the reduced resolution from the font data from which such rescalable font object was formed; and

re-writing each non-rescalable font object by thinning out such non-rescalable font object to the reduced resolution.

29. A method for managing a cache of font objects in accordance with input print data, said method comprising:

identifying a previously formed font object corresponding to a character code and font attributes specified in the input print data for a current page;

determining whether the previously formed font object is referenced from another page in a case in which a resolution reduction is requested; and

forming a new font object when it is determined that the previously formed font object is referenced from another page in a case in which a resolution reduction is requested, wherein the new font object is referenced from the current page and the previously formed font object is referenced from the other page.

30. An apparatus for re-writing font objects at a reduced resolution, said apparatus comprising:

a memory for storing font objects, font data, font information and program instruction sequences; and

a processor for executing said program instruction sequences stored in said memory,

wherein said program instruction sequences include;

(a) inspecting each font object to determine if such font object is a scalable font object or a non-scalable font object;

(b) re-writing each scalable font object by re-reading font information pertaining to the font object and using the font information to form a new font object at the reduced resolution from font data from which such scalable font object was formed; and

(c) re-writing each non-scalable font object by thinning out such non-scalable font object to the reduced resolution.

31. An apparatus for re-writing font objects at a reduced resolution, said apparatus comprising:

a memory for storing font objects, font data, font information and program instruction sequences; and

a processor for executing said program instruction sequences stored in said memory,

wherein said program instruction sequences include;

(a) inspecting each font object to determine if such font object is a rescalable font object or a non-rescalable font object, with a rescalable font object being a scalable font object for which font data from which such scalable font object was formed has not been deleted or changed, and a non-rescalable font object being a font object which is not a rescalable font object;

(b) re-writing each rescalable font object by re-reading font information pertaining to such rescalable font object and using the font information to form a new font object at the reduced resolution from the font data from which such rescalable font object was formed; and

(c) re-writing each non-rescalable font object by thinning out such non-rescalable font object to the reduced resolution.

32. An apparatus for managing a cache of font objects in accordance with input print data, said apparatus comprising:

a memory for storing font objects, input print data, font data and program instruction sequences; and

a processor for executing said program instruction sequences stored in said memory,

wherein said program instruction sequences include;

(a) identifying a previously formed font object corresponding to a character code and font attributes specified in the input print data for a current page;

(b) determining whether the previously formed font object is referenced from another page in a case in which a resolution reduction is requested; and

(c) forming a new font object when it is determined that the previously formed font object is referenced from another page in a case in which a resolution reduction is requested, wherein the new font object is referenced from the current page and the previously formed font object is referenced from the other page.