Image Sensor ADC Tessellation Tile Pattern Noise Reduction
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Solution Overview
Problem
Image sensors, including both column and area ADCs, face challenges in reducing pattern noise such as vertical stripe, horizontal stripe, and block noise, which are inherent to their internal structures, making it difficult to further improve image quality beyond a certain limit.
Innovation Solution
The solution involves configuring ADCs to read charge signals from pixels arranged in a way that creates a 'saw texture' for column ADCs and employing a tessellation tile arrangement for area ADCs, where pixels are shifted and indexed to cover the screen without overlapping, effectively blurring the boundaries of pattern noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ADCs are arranged in parallel for respective columns to read charge signals simultaneously, then reading speed and productivity are improved, but vertical stripe noise and horizontal stripe noise are generated due to the fixed pixel arrangement
Solution Approach 1:
The patent applies dynamics by making the pixel arrangement movable rather than fixed. Specifically, the pixel data is rearranged using sawtooth wave patterns and tessellation tiles, creating dynamic shifts in the spatial distribution of pixels across different ADC columns. This dynamic rearrangement prevents the formation of fixed pattern noise while maintaining simultaneous reading capability.
Solution Approach 2:
The patent employs asymmetry by introducing sawtooth wave patterns and tessellation tile arrangements that create asymmetric pixel distributions across ADC columns. Instead of uniform pixel allocation, the asymmetric arrangements ensure that adjacent columns read from different line positions, thereby disrupting the symmetry that causes vertical and horizontal stripe noise.
2Measurement precision
If noise in each pixel is reduced to the limit to improve image quality, then pixel-level noise is minimized, but pattern noise becomes more visible and dominates the image quality
Solution Approach 1:
The patent converts the harmful effect of pattern noise into a benefit by using controlled noise-like patterns (sawtooth waves and tessellation tiles) to disrupt the more harmful fixed-pattern noise. The introduced patterns act as a beneficial disturbance that masks and disperses the visibility of ADC-related pattern noise, effectively converting one form of noise into a solution for another.
Solution Approach 2:
The patent changes the spatial parameters of pixel arrangement by applying sawtooth wave transformations and tessellation tile mappings. These parameter changes in pixel positioning and ADC assignment alter the statistical distribution of noise across the image, making pattern noise less perceptible while preserving image quality.
3Ease of manufacture
If pixel arrangement is fixed for each ADC column, then device complexity is reduced and manufacturing is easier, but vertical stripe noise is generated due to ADC individual variations
Solution Approach 1:
The patent applies segmentation by dividing the pixel array into different groups that are assigned to different ADC columns in a non-uniform manner. Using sawtooth wave patterns and tessellation tiles, pixels are segmented and redistributed across columns, ensuring that each ADC processes a diverse set of pixels rather than a contiguous block, thereby reducing vertical stripe noise from ADC variations.
4Device complexity
If reading is conducted sequentially by scanning lines, then device complexity is reduced, but horizontal stripe noise is generated due to fluctuations in reading time among lines
Solution Approach 1:
The patent introduces dynamics into the reading process by implementing time-varying pixel arrangements through sawtooth wave patterns and tessellation tiles. This dynamic rearrangement causes different ADC columns to read from different line positions at different times, disrupting the fixed temporal patterns that cause horizontal stripe noise while maintaining sequential reading control.
Data Source
AI summary
The present disclosure relates to an image sensor, an electronic device, and a method for generating a tessellation tile that allows pattern noise that can be generated in an image output from an image sensor including column ADCs or area ADCs to be less visible.An image sensor according to a first aspect of the present disclosure includes analog digital converters (ADCs), each of the ADCs being provided for a column, wherein the ADCs associated with the respective columns are configured to read charge signals simultaneously from pixels arranged on lines different from one another of the respectively associated columns, the number of ADCs being a predetermined number corresponding to the number of columns, the columns being adjacent to one another. The present disclosure is applicable to any electronic device including an image sensor.