Image Sensor Brightness Correction for Manual ND Filter Insertion

Solution Overview

Problem

Conventional image sensing apparatuses do not account for the influence of removable light-reducing optical filters when calculating brightness values, leading to suboptimal image data generation and processing, especially when the filter is inserted or removed during photography.

Innovation Solution

An image sensing apparatus with a filter insertion/removal device that includes a signal processing device to calculate a first brightness value and a correction device to adjust this value based on the light reduction amount caused by the filter, allowing for controlled optical and signal processing to generate optimal image data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If an ND filter is inserted to reduce light quantity and widen the photographing brightness range, then the brightness range is extended, but the brightness value calculation becomes inaccurate because the conventional calculation does not account for the filter's light reduction

Engineering Contradiction:

Improvephotographing brightness rangeVSAvoidbrightness value calculation accuracy

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

The system performs preliminary action by detecting the ND filter insertion state before brightness value calculation, and pre-stores the light reduction amount corresponding to each filter specification. This allows the brightness value calculation to incorporate the filter's influence from the outset, ensuring accuracy while maintaining the extended brightness range.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by detecting the actual filter insertion state and using this information to correct the brightness value calculation. The detected filter state feeds back into the calculation process, allowing the system to adjust the brightness value according to the actual light reduction caused by the filter, thereby maintaining measurement precision.

Inventive Principle:

Principle #23Feedback

2Device complexity

If the brightness value calculation does not consider the ND filter influence, then the calculation process remains simple, but the white balance processing and exposure value setting become suboptimal

Engineering Contradiction:

Improvecalculation process complexityVSAvoidimage data quality

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system performs preliminary action by detecting the ND filter insertion state before brightness value calculation, and pre-stores the light reduction amount corresponding to each filter specification. This allows the brightness value calculation to incorporate the filter's influence from the outset, ensuring accuracy while maintaining the extended brightness range.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by detecting the actual filter insertion state and using this information to correct the brightness value calculation. The detected filter state feeds back into the calculation process, allowing the system to adjust the brightness value according to the actual light reduction caused by the filter, thereby maintaining measurement precision.

Inventive Principle:

Principle #23Feedback

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 accurate brightness value calculation and optimal image data generation regardless of the filter's presence, ensuring consistent image quality and proper exposure and white balance settings.

Implementation Method 1

an optical filter with nonselective transmittance that almost uniformly transmits (reduces) wavelengths in the visible spectra of a beam

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS7973829B2Image sensing apparatus, image sensing method, recording medium, and program for controlling exposure by correcting a brightness value when an optical filter is manually inserted

Publication Date: 2011.07.05 CANON KK

AI summary

An object of the invention is to provide an image sensing apparatus capable of sensing an image in consideration of the influence of inserting/removing an optical filter, an image sensing method, a recording medium, and a program. To achieve this object, a brightness value calculation unit calculates the first brightness value representing the brightness of part or all of an object which is imaged on a CCD image sensing element. A brightness value correction unit calculates the second brightness value by correcting the first brightness value calculated by the brightness value calculation unit on the basis of the light reduction amount generated by inserting an ND filter. A system controller controls an optical system and signal processing in a DSP circuit by using the second brightness value calculated by the brightness value correction unit.