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C1.WPF.Document.4.6.2 Assembly / GrapeCity.Documents.Imaging.jpeg.jj2000.j2k.quantization.dequantizer Namespace / StdDequantizerParams Class / exp Field

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    exp Field
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    The quantization step "exponent" value, for each resolution level and subband, as it appears in the codestream. The first index is the resolution level, and the second the subband index (within the resolution level), as specified in the Subband class. When in derived quantization mode only the first resolution level (level 0) appears.

    For non-reversible systems this value corresponds to ceil(log2(D')), where D' is the quantization step size normalized to data of a dynamic range of 1. The true quantization step size is (2^R)*D', where R is ceil(log2(dr)), where 'dr' is the dynamic range of the subband samples, in the corresponding subband.

    For reversible systems the exponent value in 'exp' is used to determine the number of magnitude bits in the quantized coefficients. It is, in fact, the dynamic range of the subband data.

    In general the index of the first subband in a resolution level is not 0. The exponents appear, within each resolution level, at their subband index, and not in the subband order starting from 0. For instance, resolution level 3, the first subband has the index 16, then the exponent of the subband is exp[3][16], not exp[3][0].

    Syntax
    'Declaration
     
    Public exp As Int32[]()
    public Int32[][] exp
    See Also