Method and system for converting bitmap data into page definition language commands

• US 5,659,638 A
• Filed: 06/06/1995
• Issued: 08/19/1997
• Est. Priority Date: 08/07/1992
• Status: Expired due to Term

• Current Assignee: Media Innovations LLC
• Original Assignee: RR Donnelley & Sons Company
• Inventors: Bengtson, Michael
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Tadayon, Bijan
• Application Number:
  US08/468,912
• Time in Patent Office: 805 Days
• Field of Search: 382/100, 382/209, 382/218, 382/309, 382/293, 382/317, 382/227, 382/177, 382/199, 382/181, 382/284, 382/173, 382/176, 382/178, 382/179, 382/180, 382/186, 382/187, 382/190 , 382/195, 382/203, 382/217, 382/224, 382/310, 382/240, 382/299, 358/433, 358/470, 358/462, 395/128, 395/135, 345/136
• US Class Current: 382/299
• CPC Class Codes: G06V 30/248 involving plural approaches, e.g. verification by template match; Resolving confusion among similar patterns, e.g. "O" versus "Q" G06V30/242 takes precedence
• CPC Class Codes: G06V 30/414 Extracting the geometrical structure, e.g. layout tree; Block segmentation, e.g. bounding boxes for graphics or text

Abstract

A method of and system for converting an original representation of a page element expressed in bitmap form into a page definition language representation of the page element develops an element approximation expressed in the page definition language, converts the element approximation into an approximation bitmap and compares the approximation bitmap to the original representation expressed in bitmap form to obtain an error indication. The error indication is checked to determine whether it meets a certain criterion and, if so, the element approximation is used as the page definition language representation. Otherwise, one or more further element approximations are developed until an element approximation is obtained that results in an error indication which meets the certain criterion.

Claims

1. A method of reproducing a page element by converting a bitmap representation of the page element at a first resolution into a page definition language representation of the page element, the method comprising the steps of:

(a.) establishing a first set of recognition parameters;

(b.) using the established set of recognition parameters to convert the bitmap representation into an element approximation expressed in the page definition language, wherein the element approximation includes an indication of an approximation of the identity of the page element and an indication of an approximation of a font in which the bitmap representation is expressed, and wherein the page element is reproducible from the element approximation at a second resolution different than the first resolution;

(c.) converting the element approximation into an approximation bitmap;

(d.) comparing the approximation bitmap to the bitmap representation to obtain an error indication;

(e.) determining whether the error indication meets a certain criterion; and

(f.) reproducing the page element using the element approximation as the page definition language representation if the error indication meets the certain criterion;

or

(g.) repeating steps (b.) through (f.) at least once if the error indication fails to meet the certain criterion using at least one different established set of recognition parameters until an element approximation is obtained that results in an error indication which meets the certain criterion.

2. The method of claim 1, wherein the page element comprises a character having an identity and expressed in a font and wherein the step (b.) includes the step of estimating the identity of the character and the font.

3. The method of claim 2, wherein the step of estimating the identity of the character and the font includes the step of comparing the bitmap representation with stored character bitmaps.

4. The method of claim 1, wherein the step (d.) comprises the step of subtracting the approximation bitmap from the bitmap representation to obtain the error indication.

5. The method of claim 1, wherein the page definition language comprises PostScript.

6. A method of reproducing a character by converting a bitmap representation of the character expressed in a font at a first resolution into a page definition language expression, the method comprising the steps of:

(a.) detecting a characteristic of the character;

(b.) using the detected characteristic to obtain one estimate of the identity of the character and the font;

(c.) using the detected characteristic to obtain another estimate of the identity of the character and the font to thereby develop successive estimates;

(d.) determining whether the successive estimates are the same; and

(e.) developing a page definition language expression from which the character is reproducible at a second resolution different than the first resolution, the page definition language expression including an indication of the identity of the character and an indication of the font using at least one of the estimates if the successive estimates are the same;

or

(f.) repeating the steps (c.) through (e.) at least once if the successive estimates are not the same until two successively obtained estimates are the same; and

(g.) reproducing the character using the page definition language expression.

7. The method of claim 6, wherein the step (b.) includes the steps of establishing a first set of recognition parameters and obtaining the one estimate based on the first set of recognition parameters.

8. The method of claim 7, wherein the step (c.) includes the steps of establishing a second set of recognition parameters and obtaining the other estimate based on the second set of recognition parameters.

9. The method of claim 6, wherein the step (a.) includes the step of detecting character metrics.

10. The method of claim 9, wherein each step (b.) and (c.) includes the step of comparing the detected character metrics with stored character metrics.

11. The method of claim 6, wherein the step (e.) comprises the step of developing a PostScript expression of the character and font.

12. A method of reproducing a plurality of printed characters each printed in a font at a position on a page, the method comprising the steps of:

(a.) converting the printed characters into a bitmap representation of same at a first resolution;

(b.) selecting a first character;

(c.) detecting characteristics of the character;

(d.) using the detected characteristics to develop character and font data representing the identity of the character and the font in which the character is expressed;

(e.) storing the character and font data together with position data representing the position of the character on the page;

(f.) repeating steps (c.)-(e.) for remaining characters on the page;

(g.) converting the stored character and font data and the stored position data into page definition language expressions from which the characters are reproducible at a second resolution different than the first resolution; and

(h.) using the page definition language expressions to operate a printing device so that the printing device reproduces at least one of the printed characters.

13. The method of claim 12, wherein the step (a.) comprises the step of using a scanner to convert the printed characters into the bitmap representation.

14. The method of claim 12, including the further step of dividing the bitmap representation into a plurality of blocks each of which includes a character.

15. The method of claim 12, wherein a nontext portion is printed at a certain position on the page and including the further steps of converting the nontext portion into a further page definition language expression and merging the further page definition language expression with the page definition language expressions obtained in step (g.).

16. The method of claim 12, wherein the step (d.) includes the steps of successively deriving character identity and font estimates that approach the character identity and font and developing the character and font data when successive character identity and font estimates match.

17. The method of claim 12, wherein the step (g.) comprises the step of deriving PostScript expressions from the stored character and font data and the stored position data.

18. A system capable of commanding a printing device to reproduce a page having a plurality of characters printed thereon in a font and wherein the printed page is represented by a bitmap representation at a first resolution, the system comprising:

means for detecting metrics of each character of the bitmap representation;

means responsive to the detecting means for obtaining an estimate of each character including the identity thereof and the font in which such character is printed;

means responsive to the obtaining means for comparing the estimates of the characters with the bitmap representation to obtain an error indication;

means responsive to the comparing means for successively correcting character estimates until the error indication meets a certain criterion; and

means for assembling printing device commands in a page definition language using the character estimates; and

means for commanding the printing device to execute the printing device commands and thereby reproduce the characters at a second resolution different than the first resolution.

19. The system of claim 18, in combination with means for converting the printed page into the bitmap representation.

20. The system of claim 19, wherein the developing means comprises a scanner.

21. The system of claim 18, wherein the page further includes a nontext image printed thereon represented by a nontext bitmap representation and further including means for converting the nontext bitmap representation into nontext printing device commands in the page definition language.

22. The system of claim 18, wherein the comparing means comprises means for developing an estimate representation in the page definition language from the estimates, means for converting the estimate representation into an estimate bitmap and means for subtracting the estimate bitmap from the bitmap representation to obtain the error indication.

23. The system of claim 18, wherein the means for successively correcting includes means for establishing a succession of recognition parameters and means for deriving character estimates in accordance with the succession of recognition parameters.

24. The system of claim 18, wherein the assembling means comprises means for developing commands in PostScript.

25. A method of converting a bitmap representation of a page element into a page-definition-language representation of the page element, the method comprising the steps of:

(a) establishing a first set of recognition parameters;

(b) using the established set of recognition parameters to convert the bitmap representation into an element approximation expressed in the page-definition language and having an associated storage requirement, wherein the element approximation includes an indication of an approximation of a font in which the page element is expressed, and wherein the page element is reproducible from the element approximation at a resolution that is independent of the associated storage requirement of the element approximation;

(c) converting the element approximation into an approximation bitmap;

(d) comparing the approximation bitmap to the bitmap representation to obtain an error indication;

(e) determining whether the error indication meets a certain criterion; and

(f) using the element approximation as the page-definition-language representation if the error indication meets the certain criterion;

or

(g) repeating steps (b) through (f) at least once if the error indication fails to meet the certain criterion using at least one different established set of recognition parameters until an element approximation is obtained that results in an error indication which meets the certain criterion.

26. The method of claim 25, further comprising the step of using the page definition language representation to reproduce the page element at a predetermined resolution.

27. The method of claim 26, wherein the bitmap representation has a bitmap resolution and wherein the predetermined resolution at which the page element is reproduced is independent of the bitmap resolution.

28. The method of claim 26, wherein the bitmap representation has a bitmap resolution and wherein the predetermined resolution at which the page element is reproduced exceeds the bitmap resolution.

29. The method of claim 25, wherein the page element comprises a character having an identity and expressed in a font and wherein the step (b) includes the step of estimating the identity of the character and the font.

30. The method of claim 29, wherein the step of estimating the identity of the character and the font includes the step of comparing the original representation with stored character bitmaps.

31. The method of claim 25, wherein the step (d) comprises the step of subtracting the approximation bitmap from the bitmap representation to obtain the error indication.

32. The method of claim 25, wherein the page definition language comprises PostScript.

33. A method of reproducing a printed page element, comprising:

developing a bitmap representation of the printed page element;

establishing a set of recognition parameters;

using the established set of recognition parameters to convert the bitmap representation into an editible element approximation expressed in a page definition language;

converting the element approximation into an approximation bitmap;

comparing the approximation bitmap to the bitmap representation to obtain an error indication; and

adopting the element approximation as the reproduction of the page element if the error indication satisfies a certain criterion.

34. The method of claim 33, wherein the page element comprises a character having an identity and expressed in a font and wherein the step of using includes the step of estimating the identity of the character and the font.

35. The method of claim 33, wherein the step of comparing includes the step of subtracting the approximation bitmap from the bitmap representation to obtain the error indication.

36. The method of claim 33, wherein the page definition language comprises PostScript.