Nail Detection via Oblique Lighting Shadows
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Solution Overview
Problem
Conventional drawing apparatuses face difficulties in accurately detecting the nail tip portion due to its higher luminance, making it challenging to extract the entire nail region for design printing.
Innovation Solution
A drawing apparatus with a light source unit that emits light obliquely above the nail to create shadows at the border between the nail and cuticle, allowing the control unit to detect the nail region based on these shadows, enhancing edge detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the watershed method is used to detect the nail region based on luminance, then the detection process is simple, but the nail tip portion cannot be detected accurately due to its higher luminance
Solution Approach 1:
The patent applies preliminary action by using oblique lighting to pre-create shadows at the nail border regions before detection. The light source is positioned to illuminate from above at an angle, which proactively creates shadow patterns that define the nail boundaries, especially at the high-luminance nail tip area, making subsequent detection straightforward and accurate
Solution Approach 2:
The patent changes the lighting parameter by transitioning from uniform or direct illumination to oblique illumination. This parameter change in light direction creates differential luminance distribution across the nail surface, generating shadows at the border regions that enable accurate detection of the nail tip portion while maintaining the simplicity of the detection process
2Illumination intensity
If uniform illumination is applied to the nail, then the entire nail surface is evenly lit, but the border between nail and cuticle cannot be clearly detected
Solution Approach 1:
The patent applies asymmetry by positioning the light source obliquely rather than uniformly from above. This asymmetric illumination creates a shadow gradient across the nail surface, with the shadow falling predominantly on one side of the nail border, making the nail-cuticle boundary clearly distinguishable while still providing adequate illumination of the entire nail surface
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
The solution enables accurate detection and extraction of the entire nail region, improving edge detection at both the nail tip and root sides, facilitating precise nail design printing.
Implementation Method 1
the light source unit includes at least one first light source, the first light source is disposed obliquely above the nail so that a first shadow is formed in an area including a border between the nail and a cuticle part
Data Source
AI summary
A drawing apparatus includes an object insertion portion to which an object is inserted, the object being a finger or a toe having a nail; a light source unit configured to emit light to the nail of the object inserted into the object insertion portion; an image acquisition unit configured to acquire image data of the object with the nail illuminated by the light; and a control unit.The light source unit includes at least one light source disposed obliquely above the nail so that a shadow is formed near a border between the nail and a cuticle part on the root side of the nail by the light emitted from the light source.The control unit detects a position of the border based on the shadow and detects a region of the nail based on the position of the border.