Image Sensor Bit Depth Conversion for Memory Reduction
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Solution Overview
Problem
Current image sensing devices face challenges in efficiently utilizing memory resources and achieving high dynamic range imaging, particularly in reducing memory usage and minimizing unintended effects like dark current and hot pixel issues.
Innovation Solution
The proposed image sensing device captures images under different exposure times, generates a combination image with increased bit depth, and employs a conversion circuit to maintain uniform bit depth, generate flag signals, and perform tone mapping, thereby reducing memory usage and improving resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If images are captured under different exposure times to achieve high dynamic range, then image quality is improved, but memory resource utilization increases
Solution Approach 1:
The patent extracts only the necessary image data for high dynamic range processing by generating a third image from the first image using a calculation circuit, rather than storing all raw image data. This selective extraction reduces memory requirements while maintaining the ability to achieve high dynamic range imaging through subsequent combination and processing operations.
Solution Approach 2:
The patent performs preliminary processing by generating a third image corresponding to the second image based on the first image and exposure ratio before combining images. This preliminary action prepares data in advance in a computationally efficient manner, reducing the need to store and process large amounts of raw image data later, thereby reducing memory resource utilization.
2Measurement precision
If bit depth is increased to improve resolution, then image resolution is enhanced, but memory usage increases
Solution Approach 1:
The patent changes the bit depth parameter dynamically based on the combination of images from different exposure times. The conversion circuit adjusts bit depth according to the exposure ratio and combination results, maintaining high resolution where needed while reducing bit depth in regions where it is not necessary, thereby optimizing memory usage while preserving image resolution quality.
3Quantity of substance
If complex processing operations are performed to reduce memory usage, then memory resource utilization decreases, but device complexity increases
Solution Approach 1:
The patent segments the image processing function into distinct circuits: an image sensor for capturing images, a calculation circuit for generating the third image, a combination circuit for combining images, and a conversion circuit for adjusting bit depth. This segmentation allows each component to perform a specific function efficiently, reducing overall device complexity while achieving memory resource optimization through coordinated operation of these specialized units.
4Device complexity
If standard image processing methods are used, then device complexity is minimized, but unintended effects like dark current and hot pixel issues persist
Solution Approach 1:
The patent introduces a calculation circuit as an intermediary between the image sensor and combination circuit. This intermediary generates a third image based on the first image and exposure ratio, serving as a mediator that enables high dynamic range processing while providing a structured approach to handling images from different exposure times, thereby reducing unintended effects like dark current and hot pixel issues without significantly increasing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces memory resource utilization, allows for smaller hardware design, omits unnecessary processes like deep trench isolation, decreases unintended effects, and enhances image sensor resolution.
Implementation Method 1
an image sensor that captures incident light and converts the incident light into a first image
Data Source
AI summary
An image sensing device includes an image sensor that converts incident light into a first image by operating the image sensor under a first exposure time and a second image by operating the image sensor under a second exposure time which is different from the first exposure time; a calculation circuit to receive the first image and generate a third image corresponding to the second image based on the first image and a exposure ratio between the first and the second exposure times; a combination circuit to combine the second image and the third image to generate a combination image; a conversion circuit to convert or maintain each code value of the combination image to have the same bit depth based on the combination image and the exposure ratio; and a memory circuit coupled to the conversion circuit to store image values outputted from the conversion circuit.