Image Processing Apparatus for Star Trail Composite
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Solution Overview
Problem
Existing image capturing technologies face challenges in capturing starry sky images, where very bright and dark stars cannot be synthesized effectively due to exposure adjustments that either overexpose the background or underexpose the stars, leading to loss of scene atmosphere.
Innovation Solution
An image processing apparatus and method that acquires and synthesizes multiple frames of images using different exposure amounts, performing lighten composite and gain processing to create a composite image with appropriate brightness for both star trails and background, employing a mask image to replace masked areas, ensuring proper exposure levels for both.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exposure time and sensitivity are increased to capture more stars, then the number of visible stars increases, but the background (buildings and night sky) becomes overexposed and bright, losing the scene atmosphere
Solution Approach 1:
The patent segments the image processing into multiple exposure frames (first exposure amount for stars, second exposure amount for background). By capturing and processing separate frames with different exposure levels, the system can extract star information from one exposure setting while maintaining proper background brightness in another, then combine them to avoid the trade-off between star visibility and background overexposure.
2Device complexity
If only stars within a predetermined luminance range are extracted and synthesized, then processing complexity is reduced, but very bright stars and dark stars cannot be synthesized effectively
Solution Approach 1:
The patent changes the exposure parameter to capture stars across different luminance ranges. By using multiple exposure amounts (first exposure amount for fainter stars, second exposure amount for brighter stars), the system expands the detectable star luminance range without increasing processing complexity excessively, as each exposure frame can be processed independently with standard algorithms.
3Illumination intensity
If multiple frames with different exposure amounts are captured and processed, then brightness suitability for both stars and background is achieved, but processing time increases
Solution Approach 1:
The patent performs preliminary actions by capturing multiple exposure frames in sequence during the shooting phase. The differencing operation and mask image generation are then applied to these pre-captured frames, allowing the synthesis process to work with prepared data rather than requiring real-time adjustment, thus managing processing time more effectively.
Data Source
AI summary
An image processing apparatus comprises an acquisition unit that acquires images of a plurality of continuous frames obtained by shooting a subject; and a synthesis unit which generates a second image by performing lighten composite on first images of a plurality of continuous frames acquired with a first exposure amount out of the plurality of frames of images, acquires a fourth image by performing gain processing on a third image acquired with a second exposure amount which is lower than the first exposure amount so that the fourth image has a same exposure level as the first images, and generates a composite image showing a trail of the subject by performing lighten composite on a difference image, obtained by subtracting the fourth image from the second image, and the third image.