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Relationship between turbulent image variance and average image gradient.

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    Journal of the Optical Society of America. A, Optics, Image Science, and Vision
    |June 10, 2024
    PubMed
    Summary

    Optical turbulence distorts long-path imaging. A linear relationship between image intensity variance and radiance gradient squared is validated for weak to intermediate turbulence, though some discrepancies persist.

    Area of Science:

    • Optics
    • Atmospheric Science
    • Image Processing

    Background:

    • Optical turbulence significantly degrades imaging quality over extended horizontal paths.
    • Image distortions are linked to radiance gradients in Lambertian objects.
    • Quantifying turbulence effects is crucial for clear long-range imaging.

    Purpose of the Study:

    • To investigate the relationship between image intensity variance and the average image's gradient squared in optical turbulence.
    • To test the validity of a linear model connecting these two parameters.
    • To assess the performance of this model across different turbulence strengths.

    Main Methods:

    • Analysis of imaging data collected under varying optical turbulence conditions.
    • Calculation of image intensity variance.

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  • Calculation of the average image's gradient squared.
  • Statistical comparison of measured intensity variance with predicted values based on gradient squared.

    • Main Results:

    • A linear relationship was observed between intensity variance and gradient squared for weak and intermediate optical turbulence.
    • The proposed linear model demonstrated reasonable performance in these regimes.
    • Discrepancies were noted, particularly in stronger turbulence conditions, requiring further investigation.

    Conclusions:

    • The linear relationship provides a useful approximation for characterizing optical turbulence effects in imaging for moderate conditions.
    • Further research is needed to refine the model and explain observed deviations, especially under severe turbulence.
    • This work contributes to understanding and mitigating turbulence-induced image degradation.