Method for generating a halftone of a source image

Abstract

In one aspect of the present invention, a method is provided for producing a halftone of a source image. The halftone includes halftone pixels. The halftone pixels are suitable for containing halftone dots. The method selects glyphs corresponding to intensities of regions (e.g., pixels) in the source image. The glyphs contain one or more halftone dots. The method locates halftone dots within the halftone pixels such that for at least one pair of halftone dots contained within a pair of halftone pixels sharing a common boundary, the halftone dots in the pair of halftone pixels extend in opposite directions from the common boundary.

1. A method for generating a halftone of a source image, the halftone including halftone pixels, the halftone pixels being suitable for containing halftone dots, the method comprising steps of:
 (A) selecting glyphs corresponding to regions in the source image, the regions having intensities, the glyphs including halftone dots; 
 (B) selecting, from among the halftone pixels, a first halftone pixel; 
 (C) selecting a first boundary of the first halftone pixel using a first boundary selection criterion that is dependent on a position of the first halftone pixel and independent of the intensity of the corresponding region; 
 (D) locating a first one of the halftone dots within the first halftone pixel so that the first halftone dot abuts the first pixel boundary; 
 (E) selecting, from among the halftone pixels, a second halftone pixel; 
 (F) selecting a second boundary of the second halftone pixel using a second boundary selection criterion that is dependent on a position of the second halftone pixel and independent of the intensity of the corresponding region; and 
 (G) locating a second one of the halftone dots within the second halftone pixel so that the second halftone dot abuts the second pixel boundary, wherein the first and second pixel boundaries are the same boundary. 
 
     
     
       2. The method of  claim 1 , further comprising a step of:
 (H) rendering the halftone on an output medium using an output device. 
 
     
     
       3. The method of  claim 2 , wherein the output device comprises a thermal printer. 
     
     
       4. The method of  claim 2 , wherein the step (H) rendering comprises a step of:
 (H) (1) rendering the first and second halftone dots as a single contiguous mark. 
 
     
     
       5. The method of  claim 4 , wherein the step (H) (1) rendering the first and second halftone dots as a single contiguous mark comprises a step of rendering the single contiguous mark using a print head element of a thermal printer. 
     
     
       6. The method of  claim 1 , wherein the source image comprises a digital image including a two-dimensional array of source image pixels, and wherein the regions in the source image comprise the source image pixels. 
     
     
       7. The method of  claim 6 , wherein each of the glyphs corresponds to a source image pixel. 
     
     
       8. The method of  claim 1 , wherein each of the glyphs comprises a two-dimensional array of halftone pixels. 
     
     
       9. The method of  claim 8 , wherein each of the glyphs comprises one halftone pixel. 
     
     
       10. The method of  claim 9 , wherein the size of a halftone dot contained within any one of the glyphs is inversely related to the intensity of the source image region that corresponds to the glyph. 
     
     
       11. The method of  claim 1 , wherein the first and second halftone dots are selected from one of the glyphs, and wherein the first and second halftone dots are in adjacent pixels within the selected glyph. 
     
     
       12. The method of  claim 1 , wherein the first and second pixel boundaries are perpendicular to a slow scan direction of an output device on which the halftone may be rendered. 
     
     
       13. The method of  claim 1 , wherein each of the halftone pixels has a top boundary and a bottom boundary, and wherein the method further comprises a step of:
 (E) positioning a third one of the halftone dots within a third one of the halftone pixels that is adjacent to the first halftone pixel by performing steps of: , the positioning comprising:
 (1) if the first halftone dot abuts the top boundary of the first halftone pixel, positioning the third halftone dot to abut the bottom boundary of the third halftone pixel; and 
 (2) if the first halftone dot abuts the bottom boundary of the first halftone pixel, positioning the third halftone dot to abut the top boundary of the third halftone pixel. 
 
 
     
     
       14. The method of  claim 13 , wherein diagonally opposing corners of halftone pixels lie along a line at substantially a 45-degree angle to an axis of the halftone. 
     
     
       15. The method of  claim 13 , wherein diagonally opposing corners of halftone pixels lie along a line at substantially a 38-degree angle to an axis of the halftone. 
     
     
       16. The method of  claim 1 , wherein the step (A) selecting glyphs comprises a step of:
 (A) (1) selecting glyphs corresponding to the intensities of the regions in the source image. 
 
     
     
       17. The method of  claim 16 , wherein the step (A) selecting glyphs further comprises a step of:
 (A) (2) selecting halftone dots from the glyphs based on the coordinates of the source image regions. 
 
     
     
       18. The method of  claim 1 , wherein the first one of the halftone dots is contained within a first pixel of a select selected one of the glyphs, wherein the second one of the halftone dots is contained within a second pixel of the select selected one of the glyphs, and wherein:
 the step (D) locating the first one of the halftone dots comprises locating the first one of the halftone dots within the first halftone pixel based on a location of the first one of the halftone dots within the first pixel of the select selected one of the glyphs; and wherein 
 the step (G) locating the second one of the halftone dots comprises locating the second one of the halftone dots within the second halftone pixel based on a location of the second one of the halftone dots within the second pixel of the select one of the glyphs. 
 
     
     
       19. A method for generating a halftone of a digital source image including a two-dimensional array of source image pixels, the halftone including halftone pixels, the halftone pixels being suitable for containing halftone dots, the method comprising steps of:
 (A) selecting halftone dots corresponding to source image pixels, the size of each of the halftone dots being inversely related to the intensity of one of the source image pixels; 
 (B) selecting, from among the halftone pixels, a first halftone pixel; 
 (C) selecting a first boundary of the first halftone pixel using a first boundary selection criterion that is dependent on a position of the first halftone pixel and independent of the intensity of the corresponding source image pixel; 
 (D) locating a first one of the halftone dots within the first halftone pixel so that the first halftone dot abuts the first pixel boundary; 
 (E) selecting, from among the halftone pixels, a second halftone pixel; 
 (F) selecting a second boundary of the second halftone pixel using a second boundary selection criterion that is dependent on a position of the second halftone pixel and independent of the intensity of the corresponding region source image pixel; 
 (G) locating a second one of the halftone dots within the second halftone pixel so that the second halftone dot abuts the second pixel boundary, wherein the first and second pixel boundaries are the same boundary and are perpendicular to a slow scan direction of an output device on which the halftone may be rendered; and 
 (H) rendering the halftone on an output medium using a thermal printer, wherein the step of rendering includes a step of rendering the first and second halftone dots as a single contiguous mark. 
 
     
     
       20. A method for generating a halftone of a digital source image including a two-dimensional array of source image pixels, the halftone including halftone pixels, the halftone pixels being suitable for containing halftone dots, the method comprising steps of:
 (A) identifying intensities of the source image pixels; 
 (B) selecting glyphs corresponding to the identified intensities, the glyphs including halftone dots; 
 (C) selecting halftone dots from the glyphs based on the coordinates of the source image pixels; 
 (D) selecting, from among the halftone pixels, a first halftone pixel; 
 (E) selecting a first boundary of the first halftone pixel using a first boundary selection criterion that is dependent on a position of the first halftone pixel and independent of the intensity of the corresponding source image pixel; 
 (F) locating a first one of the halftone dots within the first halftone pixel so that the first halftone dot abuts the first pixel boundary; 
 (G) selecting, from among the halftone pixels, a second halftone pixel; 
 (H) selecting a second boundary of the second halftone pixel using a second boundary selection criterion that is dependent on a position of the second halftone pixel and independent of the intensity of the corresponding source image pixel; 
 (I) locating a second one of the halftone dots within the second halftone pixel so that the second halftone dot abuts the second pixel boundary, wherein the first and second pixel boundaries are the same boundary; and 
 (J) rendering the halftone on an output medium using a thermal printer, wherein the step of rendering includes a step of rendering the first and second halftone dots as a single contiguous mark. 
 
     
     
       21. A method for generating a halftone of a source image, the halftone including halftone pixels, the halftone pixels being suitable for containing halftone dots, each of the halftone pixels having a top boundary and a bottom boundary, the method comprising steps of:
 (A) selecting glyphs corresponding to regions in the source image, the glyphs including halftone dots; 
 (B) selecting, from among the halftone pixels, a first halftone pixel and a second halftone pixel that share a pixel boundary; 
 (C) locating a first one of the halftone dots within the first halftone pixel so that the first halftone dot abuts the pixel boundary; 
 (D) locating a second one of the halftone dots within the second halftone pixel so that the second halftone dot abuts the pixel boundary; 
 (E) positioning a third one of the halftone dots within a third one of the halftone pixels that is adjacent to the first halftone pixel by performing steps of: , the positioning comprising: 
 (1) if the first halftone dot abuts the top boundary of the first halftone pixel, positioning the third halftone dot to abut the bottom boundary of the third halftone pixel; and 
 (2) if the first halftone dot abuts the bottom boundary of the first halftone pixel, positioning the third halftone dot to abut the top boundary of the third halftone pixel. 
 
 
     
     
       22. The method of  claim 21 , wherein diagonally opposing corners of halftone pixels lie along a line at substantially a 45-degree angle to an axis of the halftone. 
     
     
       23. The method of  claim 21 , wherein diagonally opposing corners of halftone pixels lie along a line at substantially a 38-degree angle to an axis of the halftone. 
     
     
       24. A non-transitory computer-readable medium comprising computer-readable instructions for generating a halftone of a source image, the halftone including halftone pixels, the halftone pixels being suitable for containing halftone dots, the computer-readable instructions comprising:
 instructions to select glyphs corresponding to regions in the source image, the regions having intensities, the glyphs including halftone dots;   instructions to select, from among the halftone pixels, a first halftone pixel;   instructions to select a first boundary of the first halftone pixel using a first boundary selection criterion that is dependent on a position of the first halftone pixel and independent of the intensity of the conesponding region;   instructions to locate a first one of the halftone dots within the first halftone pixel so that the first halftone dot abuts the first pixel boundary;   instructions to select, from among the halftone pixels, a second halftone pixel;   instructions to select a second boundary of the second halftone pixel using a second boundary selection criterion that is dependent on a position of the second halftone pixel and independent of the intensity of the conesponding region; and   instructions to locate a second one of the halftone dots within the second halftone pixel so that the second halftone dot abuts the second pixel boundary, wherein the first and second pixel boundaries are the same boundary.   
     
     
       25. The computer readable medium of claim 24, the computer-readable instructions further comprising:
 instructions to render the halftone on an output medium using an output device.   
     
     
       26. The computer readable medium of claim 25, wherein the output device comprises a thermal printer. 
     
     
       27. The computer readable medium of claim 25, wherein the instructions to render the halftone comprise:
 instructions to render the first and second halftone dots as a single contiguous mark.   
     
     
       28. The computer readable medium of claim 27, wherein the instructions to render the first and second halftone dots comprise instructions to render the single contiguous mark using a print head element of a thermal printer. 
     
     
       29. The computer readable medium of claim 24, wherein the source image comprises a digital image including a two-dimensional array of source image pixels, and wherein the regions in the source image comprise the source image pixels. 
     
     
       30. The computer readable medium of claim 29, wherein each of the glyphs corresponds to a source image pixel. 
     
     
       31. The computer readable medium of claim 24, wherein each of the glyphs comprises a two-dimensional array of halftone pixels. 
     
     
       32. The computer readable medium of claim 31, wherein each of the glyphs comprises one halftone pixel. 
     
     
       33. The computer readable medium of claim 32, wherein the size of a halftone dot contained within any one of the glyphs is inversely related to the intensity of the source image region that corresponds to the glyph. 
     
     
       34. The computer readable medium of claim 24, wherein the first and second halftone dots are selected from one of the glyphs, and wherein the first and second halftone dots are in adjacent pixels within the selected glyph. 
     
     
       35. The computer readable medium of claim 24, wherein the first and second pixel boundaries are perpendicular to a slow scan direction of an output device on which the halftone may be rendered. 
     
     
       36. The computer readable medium of claim 24, wherein each of the halftone pixels has a top boundary and a bottom boundary, and wherein the computer-readable instructions further comprise:
 instructions to position a third one of the halftone dots within a third one of the halftone pixels that is adjacent to the first halftone pixel, the instructions to position comprising:
 position the third halftone dot to abut the bottom boundary of the third halftone pixel if the first halftone dot abuts the top boundary of the first halftone pixel; and 
 position the third halftone dot to abut the top boundary of the third halftone pixel if the first halftone dot abuts the bottom boundary of the first halftone pixel. 
   
     
     
       37. The computer readable medium of claim 36, wherein diagonally opposing corners of halftone pixels lie along a line at substantially a 45-degree angle to an axis of the halftone. 
     
     
       38. The computer readable medium of claim 36, wherein diagonally opposing corners of halftone pixels lie along a line at substantially a 38-degree angle to an axis of the halftone. 
     
     
       39. The computer readable medium of claim 24, wherein the instructions to select glyphs comprise:
 instructions to select glyphs corresponding to the intensities of the regions in the source image.   
     
     
       40. The computer readable medium of claim 39, wherein the instructions to select glyphs corresponding to the intensities of the regions comprise:
 instructions to select halftone dots from the glyphs based on the coordinates of the source image regions.   
     
     
       41. The computer readable medium of claim 24, wherein the first one of the halftone dots is contained within a first pixel of a selected one of the glyphs, wherein the second one of the halftone dots is contained within a second pixel of the selected one of the glyphs, and wherein:
 the instructions to locate a first one of the halftone dots comprise instructions to locate the first one of the halftone dots within the first halftone pixel based on a location of the first one of the halftone dots within the first pixel of the selected one of the glyphs; and   wherein the instructions to locate a second one of the halftone dots comprise instructions to locate the second one of the halftone dots within the second halftone pixel based on a location of the second one of the halftone dots within the second pixel of the selected one of the glyphs.   
     
     
       42. A method for generating a halftone of a source image, the halftone including halftone pixels, the halftone pixels being suitable for containing halftone dots, the method comprising:
 selecting glyphs corresponding to regions in the source image, the regions having intensities, the glyphs including halftone dots;   selecting, from among the halftone pixels, a first halftone pixel;   locating a first one of the halftone dots within the first halftone pixel so that the first halftone dot abuts a first pixel boundary, wherein the first pixel boundary is selected using a first boundary selection criterion that is dependent on a position of the first halftone pixel and independent of the intensity of the corresponding region;   selecting, from among the halftone pixels, a second halftone pixel; and   locating a second one of the halftone dots within the second halftone pixel so that the second halftone dot abuts a second pixel boundary, wherein the second pixel boundary is selected using a second boundary selection criterion that is dependent on a position of the second halftone pixel and independent of the intensity of the corresponding region, and wherein the first and second pixel boundaries are the same boundary.   
     
     
       43. A non-transitory computer-readable medium comprising computer-readable instructions for generating a halftone of a source image, the halftone including halftone pixels, the halftone pixels being suitable for containing halftone dots, the computer-readable instructions comprising:
 instructions to select glyphs corresponding to regions in the source image, the regions having intensities, the glyphs including halftone dots;   instructions to select, from among the halftone pixels, a first halftone pixel;   instructions to locate a first one of the halftone dots within the first halftone pixel so that the first halftone dot abuts a first pixel boundary, wherein the first pixel boundary is selected using a first boundary selection criterion that is dependent on a position of the first halftone pixel and independent of the intensity of the corresponding region;   instructions to select, from among the halftone pixels, a second halftone pixel; and   instructions to locate a second one of the halftone dots within the second halftone pixel so that the second halftone dot abuts a second pixel boundary, wherein the second pixel boundary is selected using a second boundary selection criterion that is dependent on a position of the second halftone pixel and independent of the intensity of the corresponding region, and wherein the first and second pixel boundaries are the same boundary.   
     
     
       44. An output device for rendering a physical halftone on an output medium from a generated halftone of a source image, the halftone including halftone pixels, the halftone pixels being suitable for containing halftone dots, the output device comprising:
 means for selecting glyphs corresponding to regions in the source image, the regions having intensities, the glyphs including halftone dots;   means for selecting, from among the halftone pixels, a first halftone pixel;   means for selecting a first boundary of the first halftone pixel using a first boundary selection criterion that is dependent on a position of the first halftone pixel and independent of the intensity of the corresponding region;   means for locating a first one of the halftone dots within the first halftone pixel so that the first halftone dot abuts a first pixel boundary;   means for selecting, from among the halftone pixels, a second halftone pixel;   means for selecting a second boundary of the second halftone pixel using a second boundary selection criterion that is dependent on a position of the second halftone pixel and independent of the intensity of the corresponding region; and   means for locating a second one of the halftone dots within the second halftone pixel so that the second halftone dot abuts a second pixel boundary, wherein the first and second pixel boundaries are the same boundary.   
     
     
       45. The output device of claim 44, further comprising a means for printing said first halftone pixel and said second halftone pixel on the output medium. 
     
     
       46. The output device of claim 44, wherein said output medium is paper or film. 
     
     
       47. An output device for rendering a halftone pixel on an output medium from a generated halftone of a source image, the halftone including halftone pixels, the halftone pixels being suitable for containing halftone dots, the output device comprising:
 means for selecting glyphs corresponding to regions in the source image, the regions having intensities, the glyphs including halftone dots;   means for selecting, from among the halftone pixels, a first halftone pixel;   means for locating a first one of the halftone dots within the first halftone pixel so that the first halftone dot abuts a first pixel boundary, wherein the first pixel boundary is selected using a first boundary selection criterion that is dependent on a position of the first halftone pixel and independent of the intensity of the corresponding region;   means for selecting, from among the halftone pixels, a second halftone pixel; and   means for locating a second one of the halftone dots within the second halftone pixel so that the second halftone dot abuts a second pixel boundary, wherein the second pixel boundary is selected using a second boundary selection criterion that is dependent on a position of the second halftone pixel and independent of the intensity of the corresponding region, and wherein the first and second pixel boundaries are the same boundary.   
     
     
       48. The output device of claim 47, further comprising a means for printing said first halftone pixel and said second halftone pixel on the output medium. 
     
     
       49. The output device of claim 47, wherein said output medium is paper or film.