Image Brightness Adjustment Curves for Flicker-Stable Video
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Solution Overview
Problem
Conventional local tone curve mapping in image adjustment leads to changes in the locations of image contents, causing flickers in videos, especially when image stabilization is applied.
Innovation Solution
An image adjustment method that divides images into regions, computes brightness information, generates adjustment curves based on location information, and adjusts brightness values to compensate for these changes, using techniques like local tone curve mapping and weighted bilateral interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If local tone curve mapping is used to adjust brightness of images, then images may have required characteristics such as better dynamic ranges or better contrasts, but the locations of the contents (e.g., objects) in images may change causing flickers in generated video
Solution Approach 1:
The patent applies image stabilization before local tone curve mapping is applied. By pre-aligning and stabilizing the image content locations, the subsequent brightness adjustment operations work on already-stabilized regions, preventing the location shifts that cause flicker. This preliminary stabilization action ensures that when tone curves are applied to adjust brightness, the spatial positions of objects remain consistent across frames.
2Stability of the object's composition
If image stabilization is performed on video generated from adjusted images, then video stability is improved, but flickers become worse due to compounded location changes
Solution Approach 1:
The patent performs image stabilization as a preliminary step before applying local tone curve mapping for brightness adjustment. By stabilizing the image content locations first, the subsequent brightness adjustment operations are applied to already-stabilized regions, preventing the location shifts that would otherwise cause flicker during video playback. This sequence ensures that both stability and flicker-free playback are achieved.
3Illumination intensity
If local tone curve mapping adjusts brightness values of image regions, then dynamic range and contrast are improved, but flickers occur when contents move between regions
Solution Approach 1:
The patent applies image stabilization before local tone curve mapping to establish consistent spatial references. By pre-stabilizing the image content, objects remain within the same spatial regions throughout the video sequence, ensuring that the local tone curves applied for brightness adjustment consistently affect the same content areas across frames, thereby eliminating flicker caused by content moving between different brightness-adjusted regions.
Data Source
AI summary
An image adjustment method, applied to an image sensing system comprising an image sensor, comprising: (a) sensing a target image by the image sensor; (b) dividing the target image to a plurality of image regions; (c) acquiring location information of at least one first target feature in the image regions; (d) computing brightness information of each of the image regions; (e) generating adjustment curves according to the brightness information and according to required brightness values of each of the image regions; and (f) adjusting brightness values of the image regions according to the adjustment curves. The step (d) adjusts the brightness information according to the location information or the step (e) adjusts the adjustment curves according to the location information.