Method and apparatus for mapping printer resolution using lock-up-tables

• US 5,265,176 A
• Filed: 04/17/1991
• Issued: 11/23/1993
• Est. Priority Date: 04/17/1991
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Miller, Steven O.
• Primary Examiner(s): Moore, David K.
• Assistant Examiner(s): Cammarata, Michael
• Application Number:
  US07/686,732
• Time in Patent Office: 951 Days
• Field of Search: 382/47, 382/44, 358/451, 358/453, 395/128, 395/139, 395/102, 340/731
• US Class Current: 382/299
• CPC Class Codes: G06K 15/00 Arrangements for producing a permanent visual presentation of the output data , e.g. computer output printersprinting or plotting combined with another operation, e.g. with conveying, G06K17/00
• CPC Class Codes: G06K 2215/0005 Accepting output data; Preparing data for the controlling system
• CPC Class Codes: G06K 2215/0071 Post-treatment of the composed image, e.g. compression, rotation
• CPC Class Codes: G06K 2215/0077 Raster outputting to the print element(s)

Abstract

A method is disclosed of mapping raster data input of a source data set to a destination data set, wherein the source and destination data sets have different resolutions. Initially, a resolution ratio is determined between the source data set and the destination data set. The horizontal component of the source data set is converted to the resolution of the destination data set by copying select discrete groups of the source data to form a desired number of discrete groups of the destination data. A select number of vertical, or raster, rows of the horizontally converted data set are copied to form a required number of rows, thereby completing the destination data set. Look-up tables are provided to efficiently convert the horizontal component of the source data set. An apparatus for mapping raster data input includes a computation mechanism for determining the resolution ratio, and mechanisms for converting the horizontal and vertical components of the source data set into the destination data set. Additionally, a look-up table generator is provided.

Claims

1. A method of mapping raster data input of a source data set, assembled in discrete groups and having a first resolution, to a destination data set, assembled in discrete groups and having a second resolution, wherein each data set has horizontal and vertical components, comprising:

defining a resolution ratio, having a numerator "N" for the source data set, and a denominator "D" for the destination data set;

converting the horizontal component of the source data set by selectively copying N discrete groups of the source data set to form a row of the destination data set horizontal component having D discrete groups, wherein said converting includes generating N look-up tables for looking up D discrete groups of the destination data set from N discrete groups of the source data set to generate an intermediate data set including intermediate raster data patterns;

copying, selectively, N rows of the source data set to form D rows of the destination data set; and

combining one or more of said intermediate raster data patterns to produce a pixel output pattern, said combining involving a bit-wise logical combination.

2. The method of claim 1 wherein the values of D and N are integer values.

3. The method of claim 1 wherein copying includes replicating the components to expand from a relatively smaller source data set to a relatively larger destination data set.

4. The method of claim 1 wherein copying includes coalescing the components to condense from a relatively larger source data set to a relatively smaller destination data set.

5. The method of claim 1 wherein generating includes copying the horizontal components of D-N discrete groups of the source data set every N discrete groups.

6. A method of mapping raster data of a source data set, assembled in bytes and having a first resolution, to a destination data set, assembled in bytes and having a second resolution, wherein each data set has horizontal and raster components, comprising:

defining an integer resolution ratio, having an integer numerator "N" for the source data set, and an integer denominator "D" for the destination data set;

converting the horizontal component of the source data set by selectively copying N bytes of the source data set to form a row of the destination data set horizontal component having D bytes, which includes generating N look-up tables for looking up D bytes of the destination data set from N bytes of the source data set to generate an intermediate data set including intermediate raster data patterns;

copying, selectively, the raster components of N rows of the source data set to form D rows of the destination data set; and

combining one or more of said intermediate raster data patterns to produce a pixel output pattern, said combining involving a bit-wise logical combination.

7. The method of claim 6 wherein copying includes replicating the components to expand from a relatively smaller source data set to a relatively larger destination data set.

8. The method of claim 6 wherein copying includes coalescing the components to condense from a relatively larger source data set to a relatively smaller destination data set.

9. The method of claim 6 wherein converting includes copying D-N bits of the source data set every N bits to form D bits of the destination data set.

10. A method of mapping computer printer graphics of a source data set, assembled in bytes and having a first, relatively smaller resolution, to a destination data set, assembled in bytes and having a second, relatively larger resolution, wherein each data set has horizontal and vertical components, comprising:

computing an integer resolution ratio, having an integer numerator "N" for the source data set, and an integer denominator "D" for the destination data set;

converting the horizontal component of the source data set by replicating N bytes of the source data set to form D bytes of the destination data set horizontal component by looking up D bytes of the destination data set from N bytes of the source data set including generating N look-up tables, by selectively copying the horizontal components of D-N bits of the source data set every N bits; and

replicating the vertical components of D-N rows of the destination data set every N rows.

11. The method of claim 10 wherein the source data set has a resolution of 180 DPI and the destination data set has a resolution of 300 DPI, and the integer resolution ratio is 3:

5.

12. An apparatus for mapping raster data from an input source data set having a first resolution N to a output destination data set having a second resolution D, comprising:

a computation mechanism for computing an input/output resolution ratio;

a horizontal conversion mechanism for converting a horizontal component of the input data set to a horizontal component of the output data set; and

a raster conversion mechanism for converting a vertical component of the input data set to a vertical component of the output data set, said raster conversion mechanism including N look-up tables for looking up D discrete groups of the destination data set from N discrete groups of the source data set to generate an intermediate data set including intermediate raster data patterns, said raster conversion mechanism further including logic devices for logically combining one or more of said intermediate raster data patterns to produce a pixel output pattern.

13. The apparatus of claim 12 wherein which further includes a look-up table generator for generating look-up tables for the horizontal conversion mechanism.

14. The apparatus of claim 13 wherein said computation mechanism is constructed and arranged to compute an integer resolution ratio of N:

D, and wherein N look-up tables are generated.

15. The apparatus of claim 14 wherein said horizontal conversion mechanism is constructed and arranged to convert the horizontal component of the input data set by copying, selectively, D bytes of the input data set to form N bytes of the output data set horizontal component by looking up D bytes of the output data set from N bytes of the input data set.

16. The apparatus of claim 12 wherein said raster conversion mechanism is constructed and arranged to copy the raster components of D rows of the input data set to provide an output data set which has N rows of raster components.