Image Pickup Device Brightness Correction via Gamma Lookup Table
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Solution Overview
Problem
Digital cameras face challenges in achieving desired image brightness, especially when capturing distant or wide-range scenes due to the limited range of strobe lights and decreased sensitivity from downsized image pickup elements, and existing methods require complex post-processing adjustments.
Innovation Solution
An image pickup device with built-in brightness correction capabilities, utilizing an image pickup means, correction tables, and image processing circuits to adjust gradation information and histogram data in real-time, allowing for automatic brightness correction during image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a strobe light is used to compensate for luminous energy shortage, then the brightness of the image is improved, but the range of the strobe light is limited and cannot illuminate distant or wide-range scenes adequately
Solution Approach 1:
The patent applies preliminary action by performing brightness correction during the image capture process itself rather than as a post-processing step. The correction amount calculation means calculates the required brightness adjustment based on the captured image data, and the correction means applies this correction immediately, ensuring the final image has appropriate brightness without requiring subsequent manual adjustments.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the brightness parameter of the captured image through digital signal processing. The correction amount calculation means determines the appropriate brightness correction parameter based on the luminous energy shortage detection, and this parameter is applied to transform the image brightness to the desired level.
2Volume of moving object
If the camera is downsized to reduce device size, then the portability is improved, but the sensitivity of image pickup elements decreases and luminous energy shortage worsens
Solution Approach 1:
The patent replaces the mechanical approach of increasing camera size or using larger image pickup elements with a digital signal processing solution. Instead of physically enlarging the camera or sensor to improve light sensitivity, the system captures the image with the available light and then digitally corrects the brightness through the correction means, substituting physical constraints with computational processing.
Solution Approach 2:
The patent introduces an intermediary brightness correction process between the image capture and the final image output. The correction amount calculation means and correction means act as intermediaries that process the raw image data to compensate for the insufficient luminous energy, allowing the small camera to produce images with adequate brightness despite the limited light-gathering capability of its small sensor.
3Illumination intensity
If exposure control using aperture/shutter mechanism is used to optimize brightness, then the exposure is optimized for different lighting conditions, but it is impossible to correct the brightness of already captured images
Solution Approach 1:
The patent applies preliminary action by performing brightness correction during the image capture process itself rather than as a post-processing step. The correction amount calculation means calculates the required brightness adjustment based on the captured image data, and the correction means applies this correction immediately, ensuring the final image has appropriate brightness without requiring subsequent manual adjustments.
Solution Approach 2:
The patent implements self-service by enabling the camera system to automatically correct its own captured images without requiring external computer software or manual user intervention. The correction amount calculation means and correction means form a self-contained system that detects brightness issues and automatically corrects them, making the camera versatile enough to handle both exposure optimization and post-capture brightness correction.
4Illumination intensity
If software-based brightness correction is used on a personal computer, then the brightness of taken images can be corrected, but the user has to perform very complicated operations and capture images into the computer first
Solution Approach 1:
The patent implements self-service by enabling the camera system to automatically correct its own captured images without requiring external computer software or manual user intervention. The correction amount calculation means and correction means form a self-contained system that detects brightness issues and automatically corrects them, making the camera versatile enough to handle both exposure optimization and post-capture brightness correction.
Solution Approach 2:
The patent extracts the brightness correction function from the external computer environment and integrates it directly into the camera system. By incorporating the correction amount calculation means and correction means within the camera, the system eliminates the need to transfer images to a computer for correction, simplifying the user workflow while maintaining effective brightness correction capability.
Data Source
AI summary
An image pickup device includes a histogram generation unit which generates a histogram representing a brightness distribution of digital image data (RAW data) acquired during picture taking and a table change unit which calculates an amount of correction with reference to a target brightness value based on the histogram and changes gradation correction information of a gamma lookup table in accordance with the amount of correction. A gamma correction unit corrects gradation of the image data using the changed gradation correction information to generate a taken image whose brightness is corrected in accordance with the target brightness value.