Analog Dithering in Multi-Channel Imaging for Channel Mismatch

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Solution Overview

Problem

Multi-channel digital imaging systems face challenges in matching non-linear channels, leading to perceptual artifacts due to mismatched outputs, which impairs system performance and accuracy in representing captured light.

Innovation Solution

The introduction of dither, either deterministic or random, in the analog domain before digitization to improve matching between non-linear channels by adding noise that masks mismatch effects, with dither sources integrated into the analog signal processing chains of the imaging system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If non-linear AFEs are used to save power and cost, then power consumption and cost are reduced, but channel matching deteriorates leading to perceptual artifacts

Engineering Contradiction:

Improvepower consumptionVSAvoidchannel matching

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces dither as an intermediary signal added to the analog input before processing. This dither signal masks the non-linearities and mismatches in the AFE channels, allowing the use of non-linear AFEs while maintaining channel matching. The dither acts as a mediator between the non-linear AFE and the digital output, preventing perceptual artifacts.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If dither is added to improve channel matching, then channel matching is improved, but additional noise is introduced

Engineering Contradiction:

Improvechannel matchingVSAvoidnoise

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent carefully controls the parameters of the dither signal, specifically its magnitude and frequency characteristics. By optimizing these parameters, the dither effectively masks channel mismatches while minimizing the perceived noise. The dither magnitude is set to be just sufficient to mask the non-linearities without introducing excessive noise that would degrade image quality.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If multiple output codes are allowed for a given input to improve matching, then channel matching is improved, but system complexity increases

Engineering Contradiction:

Improvechannel matchingVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies dithering in the analog domain before the analog-to-digital conversion takes place. This preliminary action of adding dither before conversion simplifies the overall system architecture compared to attempting to correct mismatches after digitization. The dither is added once at the input stage, and the subsequent digital processing can straightforwardly handle the resulting multiple output codes through averaging or other simple operations.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8233069B2Dithering techniques to reduce mismatch in multi-channel imaging systems

Publication Date: 2012.07.31 ANALOG DEVICES INC

AI summary

An embodiment of the present invention may be directed to a multi channel imaging system. The multi channel imaging system may include an input for a light signal and a plurality of channel circuits. Each of the channel circuits may have an analog signal processing chain converting some portion of the light signal into to a digital representation, the plurality of channel circuits may operate in parallel. The multi channel imaging system may further comprise at least one dither circuit coupled to a point in at least one of the analog signal processing chains to add dither.