Image Processing Apparatus Clipping Negative Luminance Values
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Solution Overview
Problem
In electronic cameras using CCD or CMOS image sensors, high-speed noise removal processes often result in luminance values becoming negative, leading to issues where dark areas are inaccurately brightened during noise reduction, as conventional clipping methods fail to manage negative luminance values effectively.
Innovation Solution
An image processing apparatus and method that sets a threshold value for luminance values, clips negative values to this threshold, calculates and holds incremental values, and subtracts these from surrounding pixels' luminance values to prevent excessive brightening of dark areas, thereby maintaining accurate luminance reproduction and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional clipping methods are used to remove negative luminance values during high-speed noise reduction, then noise reduction speed is improved, but luminance accuracy deteriorates causing dark areas to be inaccurately brightened
Solution Approach 1:
The patent segments the image processing into two distinct passes: a first pass that performs clipping of negative luminance values, and a second pass that performs noise reduction. This segmentation allows each pass to be optimized independently - the first pass quickly handles the clipping operation, while the second pass performs accurate noise reduction on the corrected data, thereby resolving the contradiction between speed and accuracy.
Solution Approach 2:
The patent applies clipping as a preliminary action before noise reduction. By first correcting the negative luminance values through clipping in the first pass, the subsequent noise reduction operation in the second pass can proceed with accurate luminance data, preventing the inaccurate brightening of dark areas while maintaining high-speed processing capability.
2Object-generated harmful factors
If noise reduction processing is performed on image data with negative luminance values, then noise removal capability is improved, but luminance reproduction accuracy deteriorates
Solution Approach 1:
The patent performs clipping as a preliminary action before noise reduction processing. The first pass clips negative luminance values to prevent them from causing inaccurate brightening during subsequent noise reduction. This preliminary correction ensures that the noise reduction operation in the second pass works with accurate luminance data, thereby improving both noise removal capability and luminance reproduction accuracy simultaneously.
Solution Approach 2:
The patent segments the processing into two distinct passes: first pass for clipping and second pass for noise reduction. This segmentation allows the clipping operation to prepare the data by eliminating negative luminance values, and then the noise reduction operation can proceed with accurate data, resolving the contradiction between noise removal capability and luminance reproduction accuracy.
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
This approach effectively prevents the over-brightening of dark areas during noise reduction, ensuring accurate luminance preservation and enhanced noise reduction capabilities without increasing the average luminance value at dark parts of images.
Implementation Method 1
image data having luminance values in which object light incident via an optical system is photoelectric converted by a plurality of pixels disposed two-dimensionally
Data Source
AI summary
An image processing apparatus includes a clip part and an incremental processing part. The clip part sets a threshold value as an output luminance value of a process object pixel when a luminance value of the process object pixel of an image data having luminance values of a plurality of pixels is less than the threshold value set in advance. The incremental processing part finds and holds an incremental value of the output luminance value relative to the luminance value of the process object pixel, and finds the output luminance value of the process object pixel by subtracting the incremental value from the luminance value when the luminance value of the process object pixel is the threshold value or more.