logResiduals

Apply log residual correction to spectral data

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    Syntax

    correctedData = logResiduals(inputData)

    Description

    Add-On Required: This feature requires the Hyperspectral Imaging Library for Image Processing Toolbox add-on.

    correctedData = logResiduals(inputData) applies a log residual correction to the hyperspectral or multispectral data inputData. The log residual method divides the spectrum of each pixel by the spectral geometric mean and the spatial geometric mean, which produces a pseudoreflectance data set.

    Note

    The Hyperspectral Imaging Library for Image Processing Toolbox™ requires desktop MATLAB®, as MATLAB Online™ and MATLAB Mobile™ do not support the library.

    example

    Examples

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    This example uses:

    Open Live Script

    Read hyperspectral data into the workspace. This data is from the EO-1 Hyperion sensor, with pixel values in digital numbers.

    hcube = imhypercube("EO1H0440342002212110PY_cropped.hdr");

    Convert the digital numbers to top of atmosphere (TOA) reflectance values.

    hcube_toa = dn2reflectance(hcube);

    Apply a log residual correction to the reflectance data. 

    hcube_logR = logResiduals(hcube_toa);

    Display the contrast-stretched RGB images of the original hyperspectral data and the log residual corrected hyperspectral data.

    colorImg = colorize(hcube,Method="rgb",ContrastStretching=true);
colorImg_logR = colorize(hcube_logR,Method="rgb",ContrastStretching=true);
figure
imagesc([colorImg colorImg_logR])

    Figure contains an axes object. The axes object contains an object of type image.

    Input Arguments

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    Input spectral data, specified as one of these options:

    • hypercube object.

    • multicube object.

    • M-by-N-by-C numeric array — M and N are the number of rows and columns of pixels in the spectral data, respectively. C is the number of spectral bands.

    The input pixel values can be digital numbers, TOA radiance values, or TOA reflectance values. To convert a spectral object containing digital numbers to a spectral object containing TOA radiance or TOA reflectance data, use the dn2radiance or dn2reflectance function, respectively.

    If inputData is a multicube object, all its spectral bands must have the same data resolution. If all spectral bands of the multicube object do not have the same resolution, resample the bands using the resampleBands function, or select bands with uniform resolution using the selectBands function.

    Output Arguments

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    Corrected spectral data, returned as a hypercube or multicube object or M-by-N-by-C numeric array consistent with the input data, inputData. If the input data in inputData is of data type double, then the corrected data is also of data type double. Otherwise, the corrected data is of data type single.

    References

    [1] Green, A. A. and M. D. Craig. "Analysis of Aircraft Spectrometer Data with Logarithmic Residuals." In Proceedings of the Airborne Imaging Spectrometer Data Analysis Workshop, ed. Gregg Vane and Alexander F. H. Goetz, 111–119. Pasadena: Jet Propulsion Laboratory, 1985.

    Version History

    Introduced in R2020b

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    See Also

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