Image Processing Apparatus for High-Quality Halftone Conversion
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Solution Overview
Problem
Existing image processing methods for converting digital image data to half-tone data often result in undesirable dot patterns due to interference between the characteristics of the input image data and the threshold value matrix, leading to blurred or degraded image quality, especially in reproducing fine lines and edges.
Innovation Solution
An image processing apparatus and method that calculates a target value for a region based on pixel values and uses a threshold value matrix to determine a distribution order of dots, ensuring that the dot pattern reflects both the input image data and the output device characteristics, thereby controlling the granularity and arrangement of dots to maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a threshold value matrix is used for dither process, then the number of tones of image data is reduced, but the dot pattern quality and fine line reproduction are degraded due to interference between image data characteristics and threshold value matrix characteristics
Solution Approach 1:
The image data is divided into multiple regions, and for each region, the distribution order of dots is determined independently based on the average pixel value of that region. This segmentation allows the dither process to adapt to local characteristics of the image data, reducing interference between the threshold value matrix and image characteristics while maintaining effective tone reduction.
Solution Approach 2:
The patent applies different distribution orders to different regions of the image data based on their local characteristics. By calculating the average pixel value for each region and determining the distribution order accordingly, the method ensures that each region is processed with appropriate quality, preserving fine lines and edges while reducing the number of tones.
2Shape
If dots are arranged based on centroid position, then the dot pattern follows the threshold value matrix arrangement, but the characteristic of input image data is lost resulting in blurred half-tone image data
Solution Approach 1:
The patent calculates the average pixel value for each region before determining the distribution order of dots. This preliminary action captures the essential characteristic of the input image data in each region, which is then used to guide the dot arrangement. By performing this calculation in advance, the method preserves image characteristics while achieving the desired dot pattern arrangement.
Solution Approach 2:
The distribution order determination uses feedback from the average pixel value calculation to adjust the dot arrangement in each region. The average pixel value serves as feedback information that reflects the local image characteristics, and this feedback is used to determine the optimal distribution order, thereby preventing loss of image data characteristics while maintaining proper dot pattern arrangement.
Data Source
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AI summary
There is provided an image processing apparatus including target value calculation means (202) for calculating a target value to be output in a predetermined region in input image data based on pixel values of pixels included in the region, distribution order determination means (203) for determining a distribution order of output values for distributing output values corresponding to the target value in the region based on a pixel value of each pixel included in the region and a threshold value in the threshold matrix corresponding to the pixel, and output value determination means (205) for determining an output value of each pixel included in the region by allocating the target value to at least one pixel included in the region in the distribution order.