Low-Resolution Printing Engine Image Quality via Dithering

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Solution Overview

Problem

Low-resolution printing engines struggle to achieve image quality comparable to high-resolution engines, leading to suboptimal output when processing multilevel gray scale images.

Innovation Solution

The implementation of a resolution-enhancing dithering processing method using a dithering matrix with quadruple resolution, where pixel values are compared with multiple thresholds and weighted coefficients are applied to enhance image quality, allowing low-resolution printing engines to produce images akin to those from high-resolution engines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a low-resolution printing engine unit is used, then the cost is reduced, but the image quality deteriorates

Engineering Contradiction:
ImprovecostVSAvoidimage quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies segmentation by dividing the image processing into multiple stages: dithering processing that converts the input image into a dithered image with halftone dots, followed by superposition processing that combines multiple dithered images. This multi-stage approach allows a low-resolution printing engine to produce high-quality output by processing the image in discrete, manageable steps that compensate for the engine's resolution limitations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs dimensionality change by overlaying dithered images at different screen angles and frequencies. Instead of attempting to achieve high resolution in a single dimension, the method uses multiple layers of halftone patterns with varying orientations and densities. This multi-dimensional approach to image construction enables the low-resolution engine to simulate higher resolution through the combined effect of multiple processing layers.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If a high-resolution printing engine unit is used, then the image quality is improved, but the cost increases

Engineering Contradiction:
Improveimage qualityVSAvoidcost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent uses copying by creating multiple dithered image copies with different screen parameters and overlaying them. Rather than relying on a single high-resolution engine pass, the method generates several processed versions of the image at the low resolution and combines them. This copying and combining approach allows the system to achieve quality comparable to high-resolution engines without requiring expensive high-resolution hardware.

Inventive Principle:
Principle #26Copying

3Manufacturing precision

If dithering processing is applied to enhance resolution, then image quality is improved, but memory usage increases

Engineering Contradiction:
Improveimage qualityVSAvoidmemory usage
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent applies preliminary action by performing dithering processing on the original image before it reaches the low-resolution printing engine. The dithering converts the continuous-tone image into a halftone pattern that is optimized for the engine's resolution capabilities. By preparing the image in advance with appropriate dithering patterns and screen angles, the system reduces the computational burden during the actual printing process and minimizes the memory required for real-time processing.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2088762B1Image processing device and image processing method
Publication Date: 2012.10.24 CANON KK
  • EP2088762B1 patent drawingFigure 1
  • EP2088762B1 patent drawingFigure 2
  • EP2088762B1 patent drawingFigure 3

AI summary

A device capable of providing an image quality that is close to a high resolution printing engine unit by low resolution printing engine unit. It includes a processing unit for comparing thresholds included in a high resolution dithering matrix with a pixel value included in each pixel of a low resolution input image and for outputting multi-level gray scale signal values. In addition, the processing unit (301) includes a comparing unit (308) for comparing a pixel value of each pixel of the low resolution input image with a plurality of thresholds included in the high resolution dithering matrix; an integrating unit (309) for obtaining for each pixel the multi-level gray scale signal value by integrating a plurality of comparison results obtained for each pixel; and an output unit for outputting the multi-level gray scale signal values obtained by the integrating unit (309).