Image Processing Tone Mapping for Consistent Viewfinder Contrast
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Solution Overview
Problem
Existing image processing systems cause perceptual discomfort due to dynamically changing contrasts in electronic viewfinders based on scene brightness, leading to inconsistent contrast perception for users.
Innovation Solution
Implementing a uniform perception mode in image processing that uses absolute input/output characteristics with a constant stimulus constant, independent of maximum display luminance, to maintain consistent contrast perception across varying brightness conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the tone characteristic is changed by multiplying a power according to the brightness of the captured scene to ensure visibility in the electronic viewfinder, then the visibility of the displayed image is improved, but the user perceives different contrasts at different brightnesses causing perceptual discomfort
Solution Approach 1:
The patent changes the parameter of maximum display luminance dynamically according to scene brightness while maintaining a fixed tone characteristic. This allows the display to adapt to different lighting conditions (improving visibility) without altering the contrast relationship (maintaining perceptual consistency). The key insight is to separate luminance adjustment from tone curve modification.
2Illumination intensity
If the maximum display luminance is dynamically changed according to the brightness of the surroundings, then the visibility of the electronic viewfinder is improved, but the contrast perception becomes inconsistent giving the user a sense that something is off
Solution Approach 1:
The patent dynamically adjusts the maximum display luminance parameter based on scene brightness while keeping the tone characteristic fixed. This selective parameter change allows the display to adapt to environmental lighting conditions without altering the fundamental contrast relationships in the image, thereby maintaining perceptual stability.
3Illumination intensity
If a tone characteristic including an adjusted inverse characteristic of a display characteristic is used to generate an input image with improved visibility, then the visibility is enhanced, but the uniformity of contrast perception across different brightness conditions deteriorates
Solution Approach 1:
Instead of modifying the tone characteristic to adapt to different brightness conditions, the patent changes the maximum display luminance parameter while maintaining a fixed tone characteristic. This approach achieves adaptability to different lighting environments while preserving the uniformity of contrast perception across all brightness conditions.
Data Source
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AI summary
An image processing apparatus (105) for generating an image to display on display means (106) configured so that a setting for maximum display luminance can be changed, obtains an image signal and the setting, generates the image to display by executing image processing including tone conversion on the obtained image signal, and sets a tone characteristic used in tone conversion executed by the generating means based on the setting. The tone characteristic is for allocating a signal value of the image signal to a luminance range according to the setting, and the tone characteristic shows a relationship in which a logarithmic value of the signal value of the image signal and an absolute luminance are roughly identical in at least a portion of the luminance range, independent of the setting.