(IUCr) CIF Definition save__array_intensities.linearity

DRAFT DICTIONARY CBF/imgCIF Extensions Dictionary | Draft version 1.5 for comment

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Index

##### Image dictionary (imgCIF) version 1.5.4

# _array_intensities.linearity

Name:
`'_array_intensities.linearity'`

Definition:

            The intensity linearity scaling method used to convert
                   from the raw intensity to the stored element value:

                   'linear' is linear.

                   'offset'  means that the value defined by
                   _array_intensities.offset should be added to each
                    element value.

                   'scaling' means that the value defined by
                   _array_intensities.scaling should be multiplied with each
                   element value.

                   'scaling_offset' is the combination of the two previous cases,
                   with the scale factor applied before the offset value.

                   'sqrt_scaled' means that the square root of raw
                   intensities multiplied by _array_intensities.scaling is
                   calculated and stored, perhaps rounded to the nearest
                   integer. Thus, linearization involves dividing the stored
                   values by _array_intensities.scaling and squaring the
                   result.

                   'logarithmic_scaled' means that the logarithm base 10 of
                   raw intensities multiplied by _array_intensities.scaling
                   is calculated and stored, perhaps rounded to the nearest
                   integer. Thus, linearization involves dividing the stored
                   values by _array_intensities.scaling and calculating 10
                   to the power of this number.

                   'raw' means that the data are a set of raw values straight
                   from the detector.

Type: code

Mandatory item: yes

The data value must be one of the following:

`linear` | .

`offset` | The value defined by _array_intensities.offset should be added to each element value.

`scaling` | The value defined by _array_intensities.scaling should be multiplied with each element value.

`scaling_offset` | The combination of the scaling and offset with the scale factor applied before the offset value.

`sqrt_scaled` | The square root of raw intensities multiplied by _array_intensities.scaling is calculated and stored, perhaps rounded to the nearest integer. Thus, linearization involves dividing the stored values by _array_intensities.scaling and squaring the result.

`logarithmic_scaled` | The logarithm base 10 of raw intensities multiplied by _array_intensities.scaling is calculated and stored, perhaps rounded to the nearest integer. Thus, linearization involves dividing the stored values by _array_intensities.scaling and calculating 10 to the power of this number.

`raw` | The array consists of raw values to which no corrections have been applied. While the handling of the data is similar to that given for 'linear' data with no offset, the meaning of the data differs in that the number of incident photons is not necessarily linearly related to the number of counts reported. This value is intended for use either in calibration experiments or to allow for handling more complex data-fitting algorithms than are allowed for by this data item.

Category: array_intensities

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