Shortened Pre-Flash for Camera White Balance and Exposure
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Solution Overview
Problem
Standard pre-flashes in camera devices, typically lasting 1-5 seconds, can be irritating to people's eyes and often cause them to close, leading to additional photos and increased memory usage.
Innovation Solution
Implementing a shortened pre-flash duration of less than 400 milliseconds, which can be zero, to obtain only white balance and auto-exposure measurements, reducing eye irritation by avoiding auto-focus during the pre-flash, especially in sufficient light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard pre-flash duration of 1-5 seconds is used, then the camera can obtain accurate focus, white balance, and exposure measurements, but it causes significant eye irritation and may cause people to close their eyes
Solution Approach 1:
The patent segments the pre-flash function into two distinct phases: a shortened pre-flash (less than 400 milliseconds) for obtaining white balance and exposure measurements, and a separate auto-focus operation that does not require a pre-flash. This segmentation allows the harmful pre-flash duration to be reduced while preserving essential measurement functions through alternative timing and sequencing.
Solution Approach 2:
The patent dynamically adjusts the pre-flash duration based on operational requirements. Instead of using a fixed standard pre-flash duration of 1-5 seconds in all cases, the system adaptively shortens the pre-flash to less than 400 milliseconds when sufficient light conditions exist, and only performs auto-focus without pre-flash in such conditions. This dynamic adjustment resolves the contradiction by optimizing pre-flash duration to the minimum necessary for accurate measurements.
2Measurement precision
If a standard pre-flash duration of 1-5 seconds is used, then the camera can obtain accurate white balance and exposure measurements, but it increases the likelihood of additional photos being taken due to eye closure
Solution Approach 1:
The patent segments the measurement operations to separate white balance/exposure acquisition from auto-focus. The shortened pre-flash (less than 400 milliseconds) is used specifically for white balance and exposure measurements, while auto-focus is performed separately without requiring a pre-flash in sufficient light conditions. This segmentation eliminates the need for additional photos caused by eye closure during prolonged pre-flash, while preserving measurement accuracy.
Solution Approach 2:
The patent performs white balance and exposure measurements during a preliminary shortened pre-flash phase before the main capture decision is made. By completing these measurements in less than 400 milliseconds, the system establishes camera settings in advance, reducing the need for additional photos if subjects close their eyes during the main flash.
3Measurement precision
If a standard pre-flash duration of 1-5 seconds is used, then the camera can obtain accurate exposure measurements, but it consumes more energy and increases memory usage due to additional photos
Solution Approach 1:
The patent segments the flash usage into a shortened pre-flash phase (less than 400 milliseconds) for exposure measurement and a separate main flash phase for actual capture. By limiting the pre-flash duration and separating it from the main capture operation, the system reduces unnecessary flash energy consumption while maintaining accurate exposure measurements. This segmentation also reduces memory usage by minimizing the number of additional photos taken due to eye closure.
Solution Approach 2:
The patent applies partial action by using only the minimum necessary pre-flash duration (less than 400 milliseconds) required to obtain accurate exposure measurements, rather than using the full standard duration of 1-5 seconds. This partial action approach provides sufficient measurement data while significantly reducing flash energy consumption and the likelihood of requiring additional photos.
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
The shortened pre-flash reduces eye irritation and minimizes the need for additional photos, optimizing camera settings while maintaining image quality.
Implementation Method 1
the flash can be irritating to the eyes of one or more people in the picture and can affect the eyes of one or more people near the camera as well. For example, when the flash is being used and a user presses the shutter release of the camera device, the flash emits a pre-flash and captures data
Data Source
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AI summary
A mobile device (100) comprising a processor (338), a camera module (360), and a flash (366) configured to generate at least one of a reduced pre-flash, a standard pre-flash and a flash. The processor (338), in response to receiving an image capture request (202), is configured to receive a brightness value (204) and determine a flash status (206) based on a flash setting with the flash status being one of an off mode, on mode, and auto mode. In the event the flash status is one of the on mode and auto mode, determine whether there is sufficient light to capture an image based at least in part on a comparison of the brightness value and a flash threshold (208). In the event the brightness value is greater than the flash threshold, cause the flash to generate a shortened pre-flash (214) and obtain only a white balance measurement and an auto-exposure measurement during the shortened pre-flash.