Enhancing an Image, Such as an Image Having Bi-Valued Pixel Values
Half-toning is a method to print multi-tone images using only two-tone colors. Such methods are commonly used in publishing and computer printers. There are several kinds of half-toning processing where inverse half-toning is a method to reconstruct a multi-tone image from a half-toned image.
This invention introduced a new method, the fast edge-preserving filtering, which adopts low-complexity algorithm to perform inverse half-toning. By way of this method, an inverse half-toned image is generated by directly filtering the half-tone image in an iterative manner. This low computational complexity but high image quality method made resizing, rotating and processing of images simple, easy and quick even if you are using lower-end models of computers or computer accessories like printers and scanners. In addition, the new inverse half-toning method can be used as an edge preserving filter in applications such restoration, noise-reduction, enhancement, retouching of images, old archival images, remote sensing images, and medical images.
There are other existing methods for inverse half-toning which the complexity of the algorithm relates to the quality of the image. The higher is the complexity of the algorithm, the higher is the image quality and vice versa. Some others are too restrictive on actual applications. The state-of-the-art wavelet-based methods give the highest quality images and widest range of applications but are very computation intensive.
The fast edge-preserving filtering method is only 3 to 4 times more complicated when compared with the simplest filtering methods but can already produce images of quality close to that produced by the wavelet-based methods. Besides, the edges, known to be visually important, in the inverse half-toned images generated by the new method are much sharper than those in many other methods.
- Computer printers
- Scanners
- Photocopier
- Newspaper and magazine publishing
Patent Number: US7495805B1
Application Number: US2000512378A
Inventor: Au, Oscar Chi-Lim | Fu, Ming Sun
Priority Date: 25 Feb 2000
Priority Number: US7495805B1
Application Date: 25 Feb 2000
Publication Date: 24 Feb 2009
IPC Current: G06K001500 | G06T000500 | H04N0001405 | H04N0001407 | H04N0001409
US Class: 35800307 | 35800306 | 35800324
Assignee Applicant: The Hong Kong University of Science & Technology
Title: Enhancing an image, such as an image having bi-valued pixel values
Usefulness: Enhancing an image, such as an image having bi-valued pixel values
Summary: Method for converting a halftone image.
Novelty: Halftone image converting method, involves deriving reconstructed value of specific pixel as sum over pixels of neighborhood of product of halftone image value at one neighborhood pixel with significance coefficient of neighborhood pixel
ICT/Telecom
Image Processing
25 Feb 2000
US 7495805
TTC.PA.106
Hong Kong
