Digital Motion Picture Camera Exposure Compensation for Image Sequences
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Solution Overview
Problem
Existing methods for recording image sequences in digital motion picture cameras face challenges in maintaining image quality when adjusting parameters like diaphragm aperture, exposure time, and image recording rate, leading to non-linear effects and increased image noise.
Innovation Solution
A method involving at least two exposure changing devices, one as a variation device and another as a compensation device, controlled by a control device to adjust operation parameters to compensate for exposure changes, while keeping electrical amplification constant, using empirical calibration to account for non-linearities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the diaphragm aperture is changed to adjust depth-of-focus, then the depth-of-focus is improved, but the brightness of the image changes noticeably
Solution Approach 1:
The patent changes the electrical amplification parameter (gain factor) to compensate for changes in the optical parameter (diaphragm aperture). When the diaphragm aperture is adjusted to change depth-of-focus, the amplification factor is simultaneously adjusted to maintain constant image brightness, resolving the contradiction between depth-of-focus adjustment and brightness stability.
2Illumination intensity
If the amplification factor is increased to compensate for exposure changes, then the brightness is improved, but the image noise increases
Solution Approach 1:
The patent implements a feedback mechanism where the control device continuously monitors the actual brightness of recorded images and automatically adjusts the amplification factor to maintain optimal brightness while minimizing noise. This closed-loop control ensures that brightness compensation does not excessively increase noise levels.
Solution Approach 2:
The patent dynamically changes the amplification factor based on the specific imaging conditions and required brightness compensation, rather than using a fixed high gain. This allows optimal brightness maintenance with minimal noise increase by adjusting the gain factor to the minimum necessary level.
3Adaptability or versatility
If the exposure time is varied to create stroboscopic effects, then the image design is improved, but the brightness consistency across the sequence is affected
Solution Approach 1:
The patent changes the amplification factor in response to exposure time variations. When the exposure time is adjusted to create stroboscopic or other creative effects, the amplification factor is simultaneously modified to compensate for the brightness changes, maintaining consistent overall brightness while preserving the intended creative effect.
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
Maintains image quality by compensating for exposure changes without affecting image noise, allowing for creative control of image design parameters.
Implementation Method 1
The pixels convert impinging light into electrical signals
Data Source
AI summary
In a method for recording a sequence of images by means of a digital motion picture camera, an image sensor generates electrical signals in dependence of the exposure. At least two exposure changing devices are provided, which are configured to influence the exposure of the image sensor by a setting of a respective operation parameter. One of the exposure changing devices is provided as a variation device or can be selected as such, and a further exposure changing device is provided as a compensation device or can be selected as such. During a recording of a sequence of images, the following steps are performed: influencing the exposure of the image sensor by changing the setting value of the operation parameter of the variation device; receiving the changed setting value; determining a respective adjustment value of the operation parameter of the compensation device and outputting the respective adjustment value to the compensation device, wherein an influence on the exposure of the image sensor caused by a change in the setting value is at least substantially compensated by a change in the respective adjustment value; and operating the at least one compensation device in accordance with the outputted respective adjustment value.