Adaptive halftoning based on image content

The process as set forth in 1, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.

The process as set forth in 2, wherein the first halftoning method is an error diffusion method.

The process as set forth in 2, wherein the second method is a dither method.

A process for halftoning a continuous-tone image to form a halftone image, the process comprising the steps of:

• evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods;
• halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image;
• and introducing hysteresis to compensate for sharp transitions in the image.

The process as set forth in 5, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.

The process as set forth in 6, wherein the first halftoning method is an error diffusion method.

The process as set forth in 6, wherein the second method is a dither method.

A processor for halftoning a continuous-tone image to form a halftone image, the processor comprising:

• means for evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods;
• and
• means for halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image, wherein an activity index is used to evaluate the region.

The processor as set forth in 9, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.

The processor as set forth in 10, wherein the first halftoning method is an error diffusion method.

The processor as set forth in 10, wherein the second method is a dither method.

A processor for halftoning a continuous-tone image to form a halftone image, the processor comprising:

• means for evaluating a region of the continuous-tone image to determine suitability for halftoning by at least two different halftoning methods;
• means for halftoning the region using the most suitable halftoning method such that different halftoning methods are applied to different regions of the continuous-tone image;
• and means for introducing hysteresis to compensate for sharp transitions in the image.

The processor as set forth in 13, wherein a first halftoning method is most suitable for application to detailed continuous-tone image areas and a second halftoning method is most suitable for application to flat continuous-tone image areas.

The processor as set forth in 14, wherein the first halftoning method is an error diffusion method.

The processor as set forth in 14, wherein the second method is a dither method.