Subtractive Color Processing for Image Quality and Data Size

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Solution Overview

Problem

Conventional subtractive color processing methods are inefficient for images with many areas intended to be represented by a single color, such as graphs and graphics, leading to image quality degradation and increased processing time.

Innovation Solution

A method that identifies the most used color in an image and extracts small pixel groups with minimal color difference to this dominant color, replacing areas with significant color differences to generate a resultant image with improved quality and reduced data size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional subtractive color processing methods are used on images with many single-color areas, then processing is performed on all areas, but image quality degrades and processing time increases

Engineering Contradiction:
Improveimage qualityVSAvoidprocessing time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The image is segmented into different types of areas (single-color areas vs. multi-color areas) based on color variation analysis. This allows the processing method to be selectively applied only where necessary, rather than uniformly across the entire image, thus reducing processing time while maintaining image quality in critical areas.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different processing strategies are applied to different regions of the image based on their local characteristics. Single-color areas use one approach (color substitution with representative color), while multi-color areas use another approach (conventional processing), optimizing both quality and efficiency for each region's specific needs.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If conventional subtractive color processing methods are used on images with many single-color areas, then all areas are processed, but data size increases without significant quality improvement

Engineering Contradiction:
Improveimage qualityVSAvoiddata size
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The image is divided into single-color areas and multi-color areas, allowing differential processing. Single-color areas undergo color substitution that reduces data complexity, while multi-color areas receive conventional processing, optimizing the balance between quality and data size for each region.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Processing intensity and method are adapted to local area characteristics. In single-color areas, aggressive color substitution reduces data size effectively, while in multi-color areas, more conservative processing preserves quality without unnecessarily increasing data size.

Inventive Principle:
Principle #3Local quality

3Quantity of substance

If color reduction is performed by reducing halftone levels, then compression is achieved, but areas with similar colors are converted to identical colors, changing graph significance

Engineering Contradiction:
Improvecompression ratioVSAvoidgraph significance
Core Design Contradiction:
Quantity of substanceVSLoss of information

Solution Approach 1:

The processing approach is adapted based on local area characteristics. In single-color areas where color uniformity is acceptable, aggressive color substitution achieves compression. In multi-color areas where color distinction is critical, conventional processing preserves color variations, maintaining graph significance while still achieving some compression through selective color substitution.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The color substitution threshold and representative color selection are adjusted based on local area properties. This allows flexible control over the compression-quality tradeoff, achieving better compression in areas where it matters less while preserving critical color information in areas where it matters most.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS8395813B2Subtractive color method, subtractive color processing apparatus, image forming apparatus, and computer-readable storage medium for computer program
Publication Date: 2013.03.12 KONICA MINOLTA BUSINESS TECH INC
  • US8395813B2 patent drawing
  • US8395813B2 patent drawing
  • US8395813B2 patent drawing

AI summary

A most used color that is a most popularly used color is obtained in an image. Pixel groups formed of continued pixels having an identical color other than the most used color in the image is extracted as first pixel groups. Pixel groups having a color of which a color difference with respect to the most used color is smaller than a predetermined threshold and having a size thereof that is smaller than a predetermined size is extracted as third pixel groups among the first pixel groups thus extracted. The first pixel groups other than the third pixel groups are taken as second pixel groups. An image is generated by replacing colors of portions, which correspond to the second pixel groups in an image having an area identical with that of an image to be processed and filled with the most used color, with the corresponding second pixel groups, respectively.