Virtual Light Source Image Processing for Flash Shade Recovery
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Solution Overview
Problem
Conventional methods for capturing images without losing the object's shade, such as using multiple illumination devices, require repeated shooting under varying conditions and cannot recover lost shade, resulting in images with reduced plasticity and increased noise.
Innovation Solution
An image processing apparatus and method that utilizes a virtual light source positioned differently from the flash unit, based on distance information and shape data, to generate an image with enhanced shade and plasticity by processing the original image with virtual light source parameters, including setting the virtual light source's position, hue, and light distribution characteristics to match ambient light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If gain is applied to the captured image to compensate for brightness, then brightness is improved, but noise is amplified
Solution Approach 1:
The patent creates a virtual light source that copies the characteristics of ambient light to illuminate the object in the captured image. By generating a synthetic illumination source based on ambient light properties detected in the image, the system can compensate for brightness deficiency without amplifying noise, as the virtual light source is mathematically constructed rather than physically applied to the captured photons.
Solution Approach 2:
The patent changes the illumination parameters by introducing a virtual light source with specific position, intensity, and color temperature parameters derived from ambient light detection. This allows controlled adjustment of illumination characteristics to improve brightness while maintaining image quality, avoiding the noise amplification that occurs with simple gain application.
2Illumination intensity
If an illumination device such as electronic flash unit is used to secure sufficient brightness, then brightness is improved, but shade is lost and plasticity is reduced
Solution Approach 1:
The patent introduces a virtual light source as an intermediary between the captured image and the desired illumination effect. This virtual light source mediates the lighting conditions by computationally adding ambient light characteristics to the image, thereby preserving natural shade and plasticity while achieving sufficient brightness, unlike direct flash illumination which creates harsh lighting.
Solution Approach 2:
The patent copies the characteristics of ambient light (color temperature, intensity, direction) to create a virtual light source that replicates natural lighting conditions. This copying approach preserves the original shade and plasticity of the object by using ambient light properties rather than introducing artificial flash lighting that would alter the natural appearance.
3Shape
If multiple images are shot under multiple illumination conditions to preserve shade, then shade is improved, but shooting time and complexity increase
Solution Approach 1:
The patent copies ambient light characteristics from the captured image to create a virtual light source, eliminating the need to physically reposition illumination devices or retake images under different conditions. This single-shot approach with computational virtual lighting preserves shade while dramatically reducing shooting time and operational complexity.
Solution Approach 2:
The patent replaces the mechanical system of physically moving illumination devices and retaking images with a computational system that processes the captured image to add virtual lighting. This substitution eliminates the time and complexity associated with multiple physical shooting sessions while achieving the same artistic effect of preserving natural shade.
Data Source
AI summary
An image processing apparatus comprising: an obtaining unit configured to obtain a first image of an object shot with flashing of an illumination device and distance information of distances to a plurality of positions of the object; a determination unit configured to determine a position of a virtual light source that emits virtual light; and a processing unit configured to obtain shape information of the object based on the distance information, and generate an image in which the object is illuminated by the virtual light source by processing the first image based on the obtained shape information of the object, the distance information, and the position of the virtual light source with respect to the object.