Adaptive image resolution enhancement technology
First Claim
1. A process for halftoning a continuous-tone image to form a halftone image, the process comprising the steps of:
- processing the continuous-tone image using a high frequency halftoning screen to form a high frequency continuously halftoned image;
processing the continuous-tone image using a low frequency halftoning screen to form a low frequency continuously halftoned image; and
forming a merged image by merging the high and low frequency continuously halftoned images based upon an activity index related to local change within the continuous-tone image, wherein a merge weight is applied based upon a function of the activity index.
3 Assignments
0 Petitions
Accused Products
Abstract
An Adaptive Image Resolution Enhancement Technology (IRET) process and apparatus is described to improve halftone imaging by changing ordered halftone screen resolution according to the content of the image and managing these changes based on image content. The Adaptive IRET halftoning technique maximizes the artifact reducing properties of coarser ordered screens, while minimizing the loss of rendered detail in image areas having high spatial frequency. IRET may utilize a mixture of any ordered halftone screen (e.g. clustered-dot dither, line screen, etc.) to generate halftone dots with a number of levels, and any dispersed halftone screen to generate additional levels for the ordered halftone dots. For some printing technologies, it is preferable to minimize printing artifacts by generating coarser halftone screens, rather than finer halftone screens. Coarser screening, however, means that details in the image, text, and line art will not be rendered well. Adaptive IRET uses an activity index to change its ordered halftone screen resolution according to the content of the image. To render a page with a mixture of text, line art, area fill, and photograph, it is preferable to render the “busy” areas, such as text, line art, and edge regions in a photograph, with a higher resolution screen. On the other hand, smooth areas, such as area fill and non-edge regions in a photograph, are better rendered with a lower resolution screen.
-
Citations
18 Claims
-
1. A process for halftoning a continuous-tone image to form a halftone image, the process comprising the steps of:
-
processing the continuous-tone image using a high frequency halftoning screen to form a high frequency continuously halftoned image;
processing the continuous-tone image using a low frequency halftoning screen to form a low frequency continuously halftoned image; and
forming a merged image by merging the high and low frequency continuously halftoned images based upon an activity index related to local change within the continuous-tone image, wherein a merge weight is applied based upon a function of the activity index. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A process for halftoning a continuous-tone image to form a halftone image, the process comprising the steps of:
-
processing the continuous-tone image using a high frequency halftoning screen to form a high frequency continuously halftoned image;
processing the continuous-tone image using a low frequency halftoning screen to form a low frequency continuously halftoned image; and
forming a merged image by merging the high and low frequency continuously halftoned images based upon an activity index related to local change within the continuous-tone image, wherein the activity index is used to form an edge mask and the high and low frequency continuously halftoned images are merged to form a halftone hint mask.
-
-
10. A processor for halftoning a continuous-tone image to form a halftone image, the processor comprising:
-
high frequency means for processing the continuous-tone image using a high frequency halftoning screen to form a high frequency continuously halftoned image;
low frequency means for processing the continuous-tone image using a low frequency halftoning screen to form a low frequency continuously halftoned image; and
merging means for forming a merged image by merging the high and low frequency continuously halftoned images based upon an activity index related to local change within the continuous-tone image, wherein a merge weight is applied based upon a function of the activity index. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
-
-
18. A processor for halftoning a continuous-tone image to form a halftone image, the processor comprising:
-
high frequency means for processing the continuous-tone image using a high frequency halftoning screen to form a high frequency continuously halftoned image;
low frequency means for processing the continuous-tone image using a low frequency halftoning screen to form a low frequency continuously halftoned image; and
merging means for forming a merged image by merging the high and low frequency continuously halftoned images based upon an activity index related to local change within the continuous-tone image, wherein the activity index is used to form an edge mask and the high and low frequency continuously halftoned images are merged to form a halftone hint mask.
-
Specification