Digital Camera Exposure Correction Using Lens Identification
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Solution Overview
Problem
Conventional digital still cameras face challenges in maintaining accurate exposure control, leading to issues like loss of white gradation in highlight areas and loss of black gradation in shadow areas, especially with interchangeable lens systems, due to the need for pre-measuring and storing error amounts for various apertures and lenses, which is time-consuming and requires significant memory capacity.
Innovation Solution
A digital still camera system that includes a photometry unit for measuring object luminance, a calculating unit for determining exposure adjustments, and a correcting unit to adjust images based on the ratio of captured luminance to a target value, eliminating the need for pre-measuring errors and reducing memory requirements by using a memory part to store correction coefficients associated with mounted lenses and subject types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If error amounts are measured in advance for all lenses and apertures for storage, then exposure accuracy is improved, but memory capacity requirements and measurement time increase significantly
Solution Approach 1:
The patent segments the error measurement process by aperture value rather than requiring pre-measurement for all lens-aperture combinations. The system measures and stores error amounts only for the currently mounted lens's aperture values, dividing the overall measurement task into smaller, manageable segments that are performed on-demand rather than all at once.
Solution Approach 2:
The system dynamically adapts its measurement and storage behavior based on the mounted lens. Rather than using a static pre-measured database for all possible lenses, the system dynamically determines which error amounts to measure and store based on the currently mounted lens's identification information, optimizing memory usage according to actual operational needs.
2Measurement precision
If error amounts are measured in advance for all lenses and apertures, then exposure accuracy for interchangeable lenses is improved, but the time and trouble required for measurement increases
Solution Approach 1:
The system performs preliminary identification of the mounted lens using identification information (such as lens ID or serial number) before proceeding with error measurement. This preliminary action allows the system to know in advance which aperture values need to be measured for the current lens, avoiding unnecessary measurements and reducing overall measurement time.
Solution Approach 2:
The system uses the lens's own identification information to determine its measurement requirements. By reading the lens ID or serial number, the system enables the lens itself to specify what error amounts need to be measured, eliminating the need for external configuration or manual specification of measurement parameters.
3Reliability
If pre-measured error amounts are stored for all apertures, then exposure control reliability is improved, but the system becomes complex and requires significant memory resources
Solution Approach 1:
The patent implements a universal error measurement and correction system that works with any interchangeable lens through identification-based adaptation. The same measurement and correction mechanisms are used for all lenses, but they are dynamically configured based on the mounted lens's ID. This multi-functional approach eliminates the need for separate measurement systems for each lens type, reducing overall system complexity while maintaining reliability.
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
Enables the capture of images with proper brightness without increasing memory capacity, ensuring accurate exposure adjustments even with interchangeable lenses by dynamically calculating and applying correction coefficients based on real-time luminance measurements and lens information.
Implementation Method 1
a photometry device or the like, and determine exposure
Data Source
AI summary
A digital still camera according to the present invention can obtain an image with appropriate brightness easily without an increase in memory capacity. The digital still camera of the present invention includes: an image-capturing unit which captures a field of object to generate an image; a photometry unit which measures a luminance of a predetermined area of the field of object; a calculating unit which calculates a ratio between a luminance value of a portion of the image captured according to the luminance measured by the photometry unit, and a target luminance value of the predetermined area, the portion corresponding to the predetermined area; and a correcting unit which corrects the image generated by the image-capturing unit according to the ratio.