Solid-State Imaging Device Charge Addition for Aliasing Noise Reduction
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Solution Overview
Problem
Conventional techniques for reducing the resolution of images from solid-state imaging elements result in poor image quality due to aliasing noise, as they discard pixels without effectively addressing signal components beyond the Nyquist frequency.
Innovation Solution
An imaging device that adds electric charges from photoelectric conversion elements in a two-dimensional matrix, arranged in specific portions, to produce image data with a tentative resolution higher than the target resolution, followed by a zoom operation to reduce it, incorporating a spatial low pass filter effect to minimize aliasing noise and enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pixels are discarded to reduce resolution, then the resolution is reduced to one N-th of the original, but large aliasing noise is generated and image quality deteriorates
Solution Approach 1:
The patent applies preliminary action by performing charge addition before the zoom operation. The charge adding unit aggregates electric charges from multiple pixels (L rows and C columns) into a single charge before the zoom unit processes the image. This preliminary charge aggregation acts as a spatial low-pass filter that suppresses high-frequency components and aliasing noise generation, allowing the subsequent zoom operation to produce images with reduced resolution but maintained image quality.
2Object-generated harmful factors
If charge addition is performed in portions of L rows and C columns, then spatial low pass filter effect is achieved, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the two-dimensional array of photoelectric conversion elements into multiple portions, each consisting of L rows and C columns. The charge adding unit operates on each portion independently to aggregate charges. This segmentation approach simplifies the overall system design by breaking down the complex charge aggregation process into manageable segments, making the device more implementable while maintaining the spatial low-pass filter 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
The approach reduces aliasing noise and improves image quality by maintaining signal components at the Nyquist frequency, resulting in images with higher high-frequency components and enhanced contour correction, thereby achieving excellent image quality.
Implementation Method 1
a plurality of photoelectric conversion elements which are arranged in a two-dimensional matrix, each have a color filter of a predetermined color selected from a plurality of colors on a light-receiving surface thereof, and each store an electric charge by photoelectric conversion
Data Source
AI summary
A solid-state imaging element includes photoelectric conversion elements having a complementary or Bayer color filter array. The solid-state imaging element adds together electric charges stored in nine photoelectric conversion elements having color filters of one of multiple colors in each portion of six rows and six columns, to obtain a resulting electric charge, and outputs the resulting electric charge as one pixel. A portion for one of the colors deviates from a portion for each of the other colors by three rows and/or three columns. This pixel-addition operation produces an effect of a spatial low pass filter, thereby reducing signal components exceeding a Nyquist frequency corresponding to a target resolution. Consequently, aliasing noise in an image with the target resolution is reduced, and therefore higher image quality can be achieved, when compared with a conventional resolution reduction technique.