Font and line art rendering for multi-bit output devices

• US 8,059,311 B2
• Filed: 01/31/2008
• Issued: 11/15/2011
• Est. Priority Date: 01/31/2008
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Chang, Ching-Wei
• Primary Examiner(s): LEE, TOMMY D
• Application Number:
  US12/023,878
• Publication Number:
  US 20090195795A1
• Time in Patent Office: 1,384 Days
• Field of Search: 358/1.1, 358/1.9, 358/3.01, 358/3.06, 358/3.1, 358/3.21, 358/3.24, 358/534
• US Class Current: 358/1.9
• CPC Class Codes: H04N 1/40087 Multi-toning, i.e. converting a continuous-tone signal for reproduction with more than two discrete brightnesses or optical densities, e.g. dots of grey and black inks on white paper
• CPC Class Codes: H04N 1/52 Circuits or arrangements for halftone screening

Abstract

Multilevel color page image rendering via multi-bit output devices including the rounding of tone levels, dual tone scan patterns and the selecting or generating of halftone cells and electrophotography engines and image processors for rendering multilevel tone density objects such as font and line art.

Claims

1. A method of multilevel tone density rendering comprising:

determining a maximum tone density level of a color component of an object wherein the object data comprises a plurality of pixels and the object data is characterized by at least one color component;

snapping, via a mapping look-up table, to a rendering device-specific output level, the determined maximum tone density level based on a quantization level of the rendering device; and

rendering the plurality of pixels of the object with the color component at the snapped tone density level.

2. The method of multilevel tone density rendering as claimed in claim 1 further comprising:

determining a median tone density level of a color component of the plurality of pixels of the object data;

selecting or generating, based on the determined median tone density level, a halftone pattern having pixels characterized by the color component of the determined median tone density, and wherein the halftone pattern pixels are further characterized by a tone density level based on the determined median tone density level; and

wherein the step of rendering the plurality of pixels of the object with the color component having the snapped tone density further comprises rendering a portion of the plurality of pixels of the object with the color component of the determined median tone density according to the selected or generated halftone pattern.

3. The method of multilevel tone density rendering as claimed in claim 2 wherein the rendered tone density of the color component having the determined median tone density level is associated with the selected or generated halftone pattern.

4. The method of multilevel tone density rendering as claimed in claim 1 further comprising:

testing whether the snapped tone density level is not supported by the rendering device, and if the snapped tone density level is not supported by the rendering device, then;

determining a first device-supported tone density level greater than the snapped tone density level and a second device-supported tone density level less than the determined maximum tone density level; and

rendering the object via an application of one or more scan lines comprising the first device-supported tone density level greater than the snapped tone density level and the second device-supported tone density level less than the snapped tone density level.

5. The method of multilevel tone density rendering as claimed in claim 1 further comprising:

testing of the object data characterized by three color components, each color component associated with a tone density level, whether the tone density level of each of the three color components of the object data are within a test range of tone density levels, relative to one another, and if true;

(a) determining a tone density level of a black component based on the three color density levels, and

(b) assigning the determined tone density level of the black component as the determined maximum tone density level of a color component of the object comprising a plurality of pixels characterized by at least one color component.

6. The method of multilevel tone density rendering as claimed in claim 5 further comprising:

testing whether the snapped tone density level is not supported by the rendering device, and if not supported by the rendering device, then;

determining a first device-supported tone density level greater than the determined maximum tone density level and a second device-supported tone density level less than the determined maximum tone density level; and

rendering the object via an application of one or more scan lines comprising the first device-supported tone density level greater than the snapped tone density level and the second device-supported tone density level less than the snapped tone density level.

7. A method of multilevel tone density rendering comprising:

determining a maximum tone density level of a color component of an object comprising a plurality of pixels characterized by at least one color component;

testing whether the determined maximum tone density level is not supported by the rendering device, and if not supported by the rendering device, then;

determining a first device-supported tone density level greater than the determined maximum tone density level and a second device-supported tone density level less than the determined maximum tone density level; and

rendering the object via an application of one or more scan lines comprising the first device-supported tone density level and the second device-supported tone density level less than the snapped tone density level.

8. The method of multilevel tone density rendering as claimed in claim 7 further comprising:

determining a median tone density level of a color component of the plurality of pixels of the object;

selecting or generating, based on the determined median tone density level, a halftone pattern having pixels characterized by the color component having the determined median tone density, wherein the halftone pattern pixels are characterized by a tone density level based on the determined median tone density level; and

wherein the step of rendering pixels of the object with the color component having the snapped tone density further comprises rendering a portion of the pixels of the object with the color component having the determined median tone density according to the selected or generated halftone pattern.

9. The method of multilevel tone density rendering as claimed in claim 8 wherein the rendered tone density of the color component having the determined median tone density level is associated with the selected or generated halftone pattern.

10. The method of multilevel tone density rendering as claimed in claim 8 further comprising:

testing of the object data characterized by three color components, each color component associated with a tone density level, whether the tone density level of each of the three color components of the object data are within a test range of tone density levels, relative to one another, and if true;

(a) determining a tone density level of a black component based on the three color density levels, and

(b) assigning the determined tone density level of the black component as the determined maximum tone density level of a color component of the object comprising a plurality of pixels characterized by at least one color component.

11. A method of multilevel tone density rendering comprising:

determining a maximum tone density level of a color component of an object wherein the object data comprises a plurality of pixels and the object data is characterized by at least one color component;

snapping the determined maximum tone density level based on a quantization level of a rendering device;

rendering the plurality of pixels of the object with the color component at the snapped tone density level;

determining a median tone density level of a color component of the plurality of pixels of the object data;

selecting or generating, based on the determined median tone density level, a halftone pattern having pixels characterized by the color component of the determined median tone density, and wherein the halftone pattern pixels are further characterized by a tone density level based on the determined median tone density level; and

wherein the step of rendering the plurality of pixels of the object with the color component having the snapped tone density further comprises rendering a portion of the plurality of pixels of the object with the color component of the determined median tone density according to the selected or generated halftone pattern.

12. The method of multilevel tone density rendering as claimed in claim 11 wherein the rendered tone density of the color component having the determined median tone density level is associated with the selected or generated halftone pattern.

13. A method of multilevel tone density rendering comprising:

determining a maximum tone density level of a color component of an object wherein the object data comprises a plurality of pixels and the object data is characterized by at least one color component;

snapping the determined maximum tone density level based on a quantization level of a rendering device; and

rendering the plurality of pixels of the object with the color component at the snapped tone density level;

testing whether the snapped tone density level is not supported by the rendering device, and if the snapped tone density level is not supported by the rendering device, then;

determining a first device-supported tone density level greater than the snapped tone density level and a second device-supported tone density level less than the determined maximum tone density level; and

rendering the object via an application of one or more scan lines comprising the first device-supported tone density level greater than the snapped tone density level and the second device-supported tone density level less than the snapped tone density level.

14. A method of multilevel tone density rendering comprising:

determining a maximum tone density level of a color component of an object wherein the object data comprises a plurality of pixels and the object data is characterized by at least one color component;

snapping the determined maximum tone density level based on a quantization level of a rendering device;

rendering the plurality of pixels of the object with the color component at the snapped tone density level; and

testing of the object data characterized by three color components, each color component associated with a tone density level, whether the tone density level of each of the three color components of the object data are within a test range of tone density levels, relative to one another, and if true;

(a) determining a tone density level of a black component based on the three color density levels, and

(b) assigning the determined tone density level of the black component as the determined maximum tone density level of a color component of the object comprising a plurality of pixels characterized by at least one color component.

15. The method of multilevel tone density rendering as claimed in claim 14 further comprising:

testing whether the snapped tone density level is not supported by the rendering device, and if not supported by the rendering device, then;

determining a first device-supported tone density level greater than the determined maximum tone density level and a second device-supported tone density level less than the determined maximum tone density level; and

rendering the object via an application of one or more scan lines comprising the first device-supported tone density level greater than the snapped tone density level and the second device-supported tone density level less than the snapped tone density level.