Image Capturing Apparatus Color Noise Reduction via Dual ISO Analysis
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Solution Overview
Problem
In low illumination conditions, such as astrophotography at night, existing image capturing apparatuses face challenges in displaying a live view image at a normal frame rate without increasing ISO speed, leading to significant color noise that hinders framing due to the trade-off between frame rate and noise levels.
Innovation Solution
The apparatus performs special image-processing by capturing images at different ISO speeds, analyzing colors in the low ISO speed image, and correcting the high ISO speed image to reduce noise, allowing for a live view image to be displayed with reduced color noise at a normal frame rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the frame rate is decreased to display a bright image in low illumination conditions, then the image brightness is improved, but the time lag between live view images increases making framing difficult
Solution Approach 1:
The patent changes the ISO speed parameter to maintain a normal frame rate while improving image brightness. By increasing the ISO speed to a predetermined value or higher in low illumination conditions, the system can capture sufficient light signal without reducing the frame rate, thus resolving the contradiction between image brightness and time lag.
2Productivity
If the ISO speed is increased to maintain a normal frame rate, then the frame rate is improved, but color noise in the image increases
Solution Approach 1:
The patent applies local quality by selectively correcting color noise in specific regions of the image. The color correction processing targets regions with high probability of containing color noise (such as dark areas) while preserving color accuracy in regions where color information is important, thus reducing overall color noise while maintaining image quality.
Solution Approach 2:
The patent dynamically adjusts the ISO speed parameter based on illumination conditions. When illumination is low, the ISO speed is increased to a predetermined value or higher to maintain normal frame rate. This parameter change allows the system to achieve high frame rate while managing color noise through subsequent correction processing.
3Productivity
If the ISO speed is increased to maintain a normal frame rate, then the frame rate is improved, but the image quality deteriorates due to increased noise
Solution Approach 1:
The patent applies local quality by selectively correcting color noise in specific regions of the image. The color correction processing targets regions with high probability of containing color noise (such as dark areas) while preserving color accuracy in regions where color information is important, thus reducing overall color noise while maintaining image quality.
Solution Approach 2:
The patent employs feedback mechanisms by analyzing the captured image data to determine the level of color noise and adjusting correction parameters accordingly. The system evaluates illumination conditions and applies appropriate correction strength, creating a feedback loop that maintains image quality while preserving normal frame rate performance.
Data Source
AI summary
An image capturing apparatus includes: an image capturing section that outputs first captured-image data obtained by capturing an image at a relatively low ISO speed, and second captured-image data obtained by capturing an image at an ISO speed higher than the ISO speed for the first captured-image data; a color analysis circuit that analyzes a display color included in a display image of the first captured-image data; a color correction instructing circuit that gives an instruction to correct a display color of the second captured-image data according to a result of the analysis; and an image generation circuit that corrects the display color of the second captured-image data so as to generate an image to be displayed.