Coating Color Evaluation Image Generation via Angle-Dependent Mapping
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Solution Overview
Problem
Existing methods for evaluating metallic coating colors on industrial products struggle to predict the overall impression of the coated surface, as they do not account for the unique three-dimensional shape of each product and the resulting changes in shadow.
Innovation Solution
A method for generating a coating-color-evaluation image that associates the highest gray level with the smallest observation angle and the lowest gray level with the largest angle, allowing for the arrangement of colorimetric values in a raster scan sequence based on the order of observation angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a CS image is generated without considering three-dimensional shape, then the generation process is simple and fast, but the prediction accuracy of overall impression deteriorates
Solution Approach 1:
The image generation process is segmented into two distinct parts: (1) generating a base CS image using simple spectral reflectance calculations without 3D shape data, and (2) generating a shadow image separately and superimposing it on the CS image. This segmentation allows the system to maintain fast generation speed while improving prediction accuracy by adding shadow effects that account for three-dimensional surface characteristics.
Solution Approach 2:
A shadow image is introduced as an intermediary element that mediates between the simple CS image and the desired realistic appearance. The shadow image, generated based on surface gradient information from two-dimensional shape data, serves as a bridge that adds three-dimensional shadow effects without requiring full three-dimensional CAD data, thus improving accuracy while maintaining efficiency.
2Measurement precision
If three-dimensional CAD shape data is used to account for shadow changes, then the prediction accuracy of overall impression is improved, but the requirement for data availability and system complexity increases
Solution Approach 1:
The invention extracts only the essential shadow-related information (surface gradient) from three-dimensional shape data, rather than requiring complete three-dimensional CAD models. By taking out only the necessary gradient information from 3D surfaces and representing it through two-dimensional shape data with gradient calculations, the system achieves accurate shadow prediction while significantly reducing data requirements and system complexity.
Solution Approach 2:
Instead of requiring expensive and complex three-dimensional CAD shape data, the invention uses simpler two-dimensional shape data that can be obtained more easily and at lower cost. The two-dimensional data with gradient calculations serves as a disposable substitute that provides sufficient information for shadow generation without the overhead of full 3D modeling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the generation of a coating-color-evaluation image that accurately predicts the overall impression of a metallic-coated surface on industrial products, even without three-dimensional CAD shape data, by effectively capturing the changes in shadow and angle-dependent reflectance.
Implementation Method 1
irradiate the flat panel applied with the metallic color coating with light from a specific angle so as to calculate the spectral reflectance at various acceptance angles from the spectral reflectance obtained by receiving the reflected light at various angles
Data Source
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AI summary
This coating-color-evaluation-image generation method of generating a coating-color-evaluation image from a coating-surface image displaying a coating surface includes a spectral reflectance calculating step of calculating a spectral reflectance of a metallic coating color at each predetermined angle in an observation angle range from the spectral reflectance of the metallic coating color which is measured at a plurality of light receiving angles; a colorimetric value calculating step of calculating a colorimetric value at each predetermined angle in the observation angle range according to the spectral reflectance; a histogram generating step of measuring a number of pixels at each gray level of the coating-surface image and calculating a ratio of the number of pixels at each gray level; a mapping step of associating an observation angle at each predetermined angle in the observation angle range with each gray level of the coating-surface image; and a coating-color-evaluation image generating step of generating the colored coating-color-evaluation image by arranging the colorimetric values calculated at each predetermined angle in the observation angle range in a sequence according to the order of magnitude of the observation angles and by a quantity corresponding to the ratio of the number of pixels for each gray level associated with the observation angle.