Gray Line Reproduction in Image Processing Apparatus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The reproduction of a gray line in image processing is compromised when the paper white and black points are displaced from the achromatic axis, leading to conspicuous tint changes and a strange feeling for the viewer, especially in low lightness areas where hue angles of gray and black chromaticity points differ significantly.
Innovation Solution
An apparatus and method that set a chromaticity point as a gray reference within the color gamut, specify minimum lightness points, and generate a gray line passing through these points to ensure smooth chromaticity change from white to black, maintaining appropriate gray line reproduction by controlling the output device's color gamut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the gray line connects the paper white point and the black point directly in the color space, then the gray line reproduction is simplified, but the tint changes become conspicuous and the hue angle difference causes a strange feeling in low lightness areas
Solution Approach 1:
The gray line reproduction is divided into two segments: from the white point to an intermediate point on the achromatic axis, and from the intermediate point to the black point. This segmentation allows the first segment to maintain smooth chromaticity transition while the second segment controls the hue angle difference to prevent strange feelings in low lightness areas.
Solution Approach 2:
An intermediate point on the achromatic axis is introduced as a mediator between the white point and the black point. This intermediate point serves as a transition point that ensures smooth chromaticity change in the first segment while allowing control over the hue angle in the second segment, thus resolving the contradiction between simplicity and accuracy.
2Adaptability or versatility
If process black is used by mixing color materials with black color material to change tint, then deeper gray can be expressed, but the tint change becomes conspicuous on the gray line when paper white point and black point are displaced from the achromatic axis
Solution Approach 1:
Different quality control is applied to different segments of the gray line. In the first segment (white point to intermediate point), smooth chromaticity transition is prioritized. In the second segment (intermediate point to black point), hue angle control is prioritized to prevent strange feelings. This local quality differentiation resolves the contradiction between gray tone versatility and chromaticity smoothness.
3Manufacturing precision
If the gray line is controlled to smoothly change chromaticity from paper white point to black point, then the gray line reproduction is improved, but the hue angle difference between gray and black chromaticity points still causes a strange feeling in low lightness areas
Solution Approach 1:
The gray line reproduction dynamically adjusts the hue angle control based on the segment. The first segment allows dynamic chromaticity change for smooth transition, while the second segment applies dynamic hue angle control to ensure the hue angle difference does not cause strange feelings. This dynamic approach resolves the contradiction between chromaticity smoothness and perception naturalness.
Data Source
AI summary
An apparatus sets a chromaticity point serving as a gray reference in a color gamut of a color space that an output device is able to output, specifies, in the color gamut of the color space that the output device is able to output, a first minimum lightness point on a lightness axis of the set chromaticity point and a second minimum lightness point that is achromatic, and generates a gray line that passes through a black point that is a minimum lightness point on a line connecting the first minimum lightness point and the second minimum lightness point, the first minimum lightness point, and the set chromaticity point and reaches a white point in the color gamut of the color space that the output device is able to output.