Image Processor Motion-Adapted HDR Synthesis Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image processors for generating high dynamic range (HDR) images struggle with noise and flicker, particularly when dealing with varying exposure times and subject motion, leading to suboptimal signal-to-noise ratios (S/N) in the resulting images.
Innovation Solution
An image processor that captures a first image with a first sensor gain in a first exposure time and a second image with a second sensor gain in a longer exposure time, adjusts luminance levels, detects motion, calculates a motion blending ratio, and synthesizes images to control exposure sensitivities, ensuring the first sensor gain is equal to or lower than the second sensor gain, thereby reducing noise and flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the first exposure time is shorter than the second exposure time to capture motion, then motion blur is reduced, but noise increases due to lower light intake
Solution Approach 1:
The patent combines multiple images with different exposure times to create an HDR image. The first image (shorter exposure) captures motion details with less blur, while the second image (longer exposure) provides better light intake and lower noise. By merging these complementary images, the system achieves both motion accuracy and low noise in the final composite image.
Solution Approach 2:
The patent changes the exposure time parameter between the first and second images. The first image uses a shorter exposure time to freeze motion, while the second image uses a longer exposure time to maximize light intake. This parameter variation allows the system to capture different aspects of the scene that can be combined to overcome the limitations of using a single exposure time.
2Illumination intensity
If the sensor gain is increased to brighten the first image, then the luminance level matches the second image, but noise and flicker increase
Solution Approach 1:
The patent introduces an intermediary approach by using the second image (with longer exposure and inherently higher luminance) as the primary reference, rather than attempting to brighten the first image through high sensor gain. This intermediary strategy allows the system to achieve luminance matching without the harmful side effects of high gain amplification.
Solution Approach 2:
The patent applies partial action by selectively adjusting the luminance of only the first image to match the second image, rather than uniformly processing all images. This selective adjustment is applied only where needed to achieve proper exposure matching, avoiding unnecessary gain application that would introduce noise and flicker.
3Manufacturing precision
If multiple images with different exposure times are synthesized, then HDR image quality is improved, but processing complexity increases
Solution Approach 1:
The patent segments the HDR image synthesis process into distinct stages: first capturing multiple images with different exposure times, then processing them separately through motion detection, motion compensation, and finally combining them. This segmentation of the complex synthesis process into manageable steps reduces overall processing complexity while maintaining high HDR image quality.
Solution Approach 2:
The patent performs preliminary actions before the final synthesis by detecting motion and applying motion compensation to individual images beforehand. This preliminary processing prepares the images for combination, making the final synthesis step simpler and more efficient, thereby reducing overall processing complexity while preserving image quality.
Data Source
AI summary
An image processor includes: an image sensor outputting a short exposure image and a long exposure image; a sensor controller that, when brightness of the subject changes, controls first exposure sensitivity to cause the short exposure image to have first brightness and controls second exposure sensitivity to cause the long exposure image to have second brightness; a motion blending ratio calculator calculating a motion blending ratio based on a motion amount of the subject; a motion-adapted image synthesizer generating a motion-adapted image by synthesizing a corrected short exposure image and the long exposure image based on the motion blending ratio; and an HDR image synthesizer generating an HDR image by synthesizing the motion-adapted image and the short exposure image together. When the subject becomes darker, the sensor controller controls the first and second exposure sensitivities to cause the first sensor gain to be at most the second sensor gain.