Image Brightness Correction Curve for Noise-Free Contrast
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Solution Overview
Problem
Image sensors in portable devices face challenges in maintaining high contrast and image quality due to non-uniform light permeability and distance issues, leading to amplified noise in edge pixels, which deteriorates the image quality.
Innovation Solution
An image brightness correction apparatus and method using a correction curve that adjusts contrast based on the position of pixels relative to the center pixel, increasing contrast for darker areas and decreasing it for brighter areas, represented as a lookup table or varying gradients, to smooth image brightness without amplifying noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional lens is used in portable devices with miniaturization, then the device size is reduced, but the light permeability becomes non-uniform and noise is amplified in edge pixels
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values for each pixel position in a lookup table before image processing. The correction values compensate for the non-uniform light permeability and noise amplification that occur in miniaturized devices. During image processing, these pre-computed correction values are directly applied to each pixel based on its position, effectively correcting the noise and brightness non-uniformity without requiring real-time complex calculations.
2Length of moving object
If the distance between lens and photographed surface is reduced for miniaturization, then the device becomes more compact, but the brightness of the lens becomes insufficient and light permeability becomes non-uniform
Solution Approach 1:
The patent applies local quality by implementing position-dependent correction values in the lookup table. Each pixel position (center, edge, corner) has its own specific correction value tailored to its local characteristics. The correction values vary across the image sensor surface, with different brightness compensation levels applied to different regions. This allows the system to compensate for the non-uniform light permeability caused by reduced lens-to-sensor distance, ensuring each local area receives appropriate brightness correction.
3Device complexity
If the lens is positioned farther toward the outside for miniaturization, then the device structure is simplified, but the amount of light reaching edge pixels decreases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the correction values in the lookup table based on pixel position parameters. The correction values are calculated to compensate for the reduced light amount reaching edge pixels when the lens is positioned farther toward the outside. By changing the correction parameters according to position, the system effectively compensates for the light quantity deficiency without requiring complex mechanical adjustments to lens positioning.
Data Source
AI summary
An apparatus and a method of smoothing the brightness of an image photographed in an image sensor without amplifying a noise component of a surrounding part of the image are disclosed. The image brightness correction apparatus correcting the brightness of an image by using a correction curve can include an image input unit, receiving an image; a correction gradient selection unit, selecting a gradient of the correction curve corresponding to an object pixel, having the brightness desired to be corrected, of pixels of the image; a correction performance unit, converting original brightness of the object pixel into correction brightness according to the correction curve having the selected gradient; and an image output unit, outputting the image allowing the object pixel to have the correction brightness by the correction performance unit; whereas the correction curve increases the contrast of the corresponding correction brightness if the original brightness is the same as or smaller than a predetermined brightness, and the correction curve decreases the contrast of the corresponding correction brightness if the original brightness is larger than a predetermined brightness. With the present invention, a dynamic range of an image is smooth and the contrast of the image is acquired.