Camera Dome Noise Reduction via Zoom-Adaptive Low-Pass Filtering

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Solution Overview

Problem

Cameras face challenges in capturing images with spatial frequencies above their sensor cutoff frequency, leading to noise and inefficient compression due to the camera dome's cutoff frequency being greater than the sensor's, especially when zoomed, resulting in captured noise components being above the image cutoff frequency.

Innovation Solution

Determining the current zoom value and modulation transfer function of the camera dome, applying a low-pass filter to the image based on these values to set the filter's cutoff frequency equal to the image cutoff frequency, thereby filtering out noise and enhancing compression efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the camera dome's cutoff frequency is greater than the sensor's cutoff frequency, then more spatial frequencies can pass through the dome, but noise components above the image cutoff frequency are captured and compression efficiency decreases

Engineering Contradiction:

Improvespatial frequency captureVSAvoidcompression efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the low-pass filter cutoff frequency based on the zoom level. At higher zoom levels, the cutoff frequency is reduced to match the effective image cutoff frequency, preventing noise capture. At lower zoom levels, the cutoff frequency is increased to capture more spatial frequencies. This dynamic parameter adjustment resolves the contradiction between capturing spatial frequencies and avoiding noise.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamics by making the filter cutoff frequency adaptive rather than fixed. The system continuously monitors the zoom level and adjusts the cutoff frequency accordingly, allowing the system to optimize between spatial frequency capture and noise rejection based on current operating conditions.

Inventive Principle:

Principle #15Dynamics

2Productivity

If a low-pass filter is applied to remove noise, then compression efficiency improves, but spatial frequencies above the sensor cutoff frequency are lost

Engineering Contradiction:

Improvecompression efficiencyVSAvoidspatial frequency retention

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent uses parameter changes to set the low-pass filter cutoff frequency equal to the image cutoff frequency, which is determined by the sensor's cutoff frequency and zoom level. This ensures that only frequencies above the sensor's capability are filtered out, preserving as much useful spatial frequency information as possible while removing noise.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system incorporates feedback by using the zoom level information to dynamically determine the appropriate cutoff frequency. The feedback loop ensures that the filter settings adapt to the current optical configuration, maintaining optimal balance between noise reduction and spatial frequency preservation.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If the low-pass filter cutoff frequency is set high, then more spatial frequencies are captured, but noise components are retained

Engineering Contradiction:

Improvespatial frequency captureVSAvoidnoise

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by setting the low-pass filter cutoff frequency dynamically based on the zoom level. At high zoom levels, the cutoff frequency is lowered to exclude noise while preserving useful frequencies. At low zoom levels, the cutoff frequency is raised to capture more spatial frequencies. This dynamic adjustment resolves the contradiction between capturing frequencies and rejecting noise.

Inventive Principle:

Principle #35Parameter changes

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 reduces image noise and improves compression efficiency by filtering out high-frequency components above the image cutoff frequency, allowing for more efficient bandwidth usage during image transmission and storage.

Implementation Method 1

applying a first low-pass filter to an image captured by the camera based on the current zoom value and the first modulation transfer function of the transparent dome

Methodology Applied

Scientific EffectLow-pass filtering: Filter (optical)

Implementation Method 2

determining a first modulation transfer function of a transparent dome of the camera

Methodology Applied

Scientific EffectOptical transfer function:

Data Source

PatentUS10580121B2Image noise reduction based on a modulation transfer function of a camera dome

Publication Date: 2020.03.03 AXIS

AI summary

A method and apparatus are disclosed. The method may include determining a current zoom value of a camera and determining a first modulation transfer function of a transparent dome of the camera. The method may include applying a first low-pass filter to an image captured by the camera based on the current zoom value and the first modulation transfer function of the transparent dome.