US 5,309,526 A · Image processing system

Abstract

An image-processing system for perceptual coding of images by analyzing one or more images to determine levels of imperceptible noise and encoding a first image to produce encoded values without introducing noise exceeding a determined level of imperceptible noise is disclosed. Analyzing of images is carried out under a set of user determined conditions comprising viewing distance and lighting. The encoded image is communicated and decoded to produce representation of the first image for display. As part of displaying the representation of the first image, a halftoning process is carried out. The halftoning process may comprise the interpolation of data values of the representation of the first image as well as the addition of micro-dither to the representation. Illustrative halftoning techniques include classical halftoning, least-squares halftoning, and error diffusion halftoning. Printer model-based halftoning techniques for both least-squares halftoning and error diffusion halftoning are presented. Applications of the model-based halftoning techniques for systems employing conventional coding of images are also discussed.

Claims14

Dependent claims

A method of communicating a first image based on one or more levels of imperceptible noise, the one or more levels of imperceptible noise determined based on an analysis of images generated by a device for displaying multi-level halftone images, the method comprising the step of:

a. encoding the first image to produce one or more encoded values without introducing in a value noise which exceeds a determined level of imperceptible noise;
b. communicating the one or more encoded values;
c. decoding the encoded values to produce a representation of the first image;
d. determining a halftone image based on the representation of the first image, which representation comprises one or more input signals, said step of determining a halftone image including the steps of
1. forming past signals predictive of regions of halftone images formed by a display device in response to applied binary signals,
2. modifying each of a plurality of the input signals in response to one or more past error signals, the past error signals reflecting differences between the past modified input signals and said past signals predictive of regions of halftone images, and
3. forming a binary signal in response to each of a plurality of the modified input signals;
and
e. displaying the halftone image with use of one or more formed binary signals.

6 more elements

a. encoding the first image to produce one or more encoded values without introducing in a value noise which exceeds a determined level of imperceptible noise;
b. communicating the one or more encoded values;
c. decoding the encoded values to produce a representation of the first image;
d. determining a halftone image based on the representation of the first image, which representation comprises one or more input signals, and wherein the step of determining a halftone image includes the steps of
1. filtering said input signals using an eye-model filter reflecting characteristics of human vision to derive first signals representative of an estimate of the gray scale image as perceived by the eye,
2. filtering sequences of binary signals using a two-dimensional filter reflecting characteristics representative of said display device to produce second signals representing an estimate of the output of said display device,
3. filtering said second signals using an eye-model filter to produce third signals,
4. forming an error signal representative of a difference between said first and third signals, and
5. selecting as the binary signals to be applied to said display device that sequence which realizes some preselected criterion for said error signal;
and
e. displaying the halftone image with use of one or more selected binary signals.

8 more elements

Dependencies are inferred from the claim text.

Image processing system

Life of this patent

Image processing system

Life of this patent

Abstract

Claims14