Feldkamp Filtration Phase
PARTAG_OFFSET
PARTAG_OFFSET
Defines: a constant value as ADC offset (constant uniform dark field)
Value type: integer
Default value: 0
PARTAG_AIRLEVEL
PARTAG_AIRLEVEL
Defines: a constant value as the air intensity
Value type: integer
Default value: 32000
PARTAG_SCALEFACTOR
PARTAG_SCALEFACTOR
Factor for fitting the dynamic range of the filtered projections into signed word scale
Value type: float
Default value: 700
OPTTAG_AIRCAL
OPTTAG_AIRCAL
Defines: If set to 1 then air raw (bright field) calibration in Feldkamp filtering phase is being applied
Value type: integer (can be 0 or 1)
Default value: 1
OPTTAG_LOG
OPTTAG_LOG
Defines: If set to 1 then logarithm operation in Feldkamp filtering phase is being applied
Value type: integer (can be 0 or 1)
Default value: 1
OPTTAG_OFFSET
OPTTAG_OFFSET
Defines: If set to 1 then ADC offset (dark field) calibration in Feldkamp filtering phase is being applied
Value type: integer (can be 0 or 1)
Default value: 1
OPTTAG_FFT
OPTTAG_FFT
Defines: If set to 1 then filtering operation in Feldkamp filtering phase is being applied
Value type: integer (can be 0 or 1)
Default value: 1
OPTTAG_PARKER
OPTTAG_PARKER
Defines: If set to 1 then filtering operation in Feldkamp filtering phase is being applied
Value type: integer (can be 0 or 1)
Default value: 1
OPTTAG_SLVERTFILT
OPTTAG_SLVERTFILT
Defines: If set to 1 then a vertical smoothing (along axis of rotation) in Feldkamp filtering phase is being applied. Smoothing aperture = 3.
Value type: integer (can be 0 or 1)
Default value: 1
OPTTAG_VRTSMOOTH
OPTTAG_VRTSMOOTH
Defines: If set to 1 then a vertical smoothing (along axis of rotation) in Feldkamp filtering phase is being applied. Smoothing aperture = 5.
Value type: integer (can be 0 or 1)
Default value: 0
PARTAG_PREPROSMOOTHFACTOR
PARTAG_PREPROSMOOTHFACTOR
Defines: When PARTAG_PREPROSMOOTHFACTOR is set to a number different than 0 then a 2-dimensional non-linear filter is being applied. This filter has the following parameters: hori-zontal and vertical aperture and a signal standard deviation to control a boundary-preserving behavior (to set the level of noise). This filter is being applied in the spatial domain on pre-FFT stage (on the logged attenuation signal representation) to normalized preprocessed signal. The filter is defined by three parameters: Ax (horizontal aperture), Ay (vertical aperture), V (signal variation).
Use PARTAG_PREPROSMOOTHFACTOR to set up the value of V. Since the procedure is being applied on the normalized integer signal please make multiple experiments with various V to find out an optimal value. It should provide the best compromise between keeping all boundaries preserved and the signal value. A particular setup depends on the application and the scale factor.
Value type: integer (0-255)
Default value: 3
PARTAG_PREPROSMOOTHAPRTHRZ
PARTAG_PREPROSMOOTHAPRTHRZ
Defines: When PARTAG_PREPROSMOOTHFACTOR is set to a number different than 0 then 2-dimensional non-linear filter is being applied. This filter has the following parameters: horizon-tal and vertical aperture and a signal standard deviation to control boundary-preserving behavior (to set the noise level). This filter is being applied in the spatial domain, pre-FFT stage (on the logged attenuation signal representation) to normalized preprocessed signal. The filter is defined by three parameters:
Ax (horizontal aperture), Ay (vertical aperture), V (signal variation). Use PARTAG_ PREPROSMOOTHAPRTHRZ to control Ax.
Value type: integer (0-11)
Default value: 0
PARTAG_PREPROSMOOTHAPRTVRT
PARTAG_PREPROSMOOTHAPRTVRT
Defines: When PARTAG_PREPROSMOOTHFACTOR is set to a number different than 0 then 2-dimensional non-linear filter is being applied. This filter has the following parameters: horizon-tal and vertical aperture and a signal standard deviation to control boundary-preserving behavior (to set the noise level). This filter is being applied in the spatial domain, pre-FFT stage (on the logged attenuation signal representation) to normalized preprocessed signal. The filter is defined by three parameters: Ax (horizontal aperture), Ay (vertical aperture), V (signal variation).
Use PARTAG_PREPROSMOOTHAPRTVRT to control Ay
Value type: integer (0-11)
Default value: 3
OPTTAG_ZFILTER<NN>
OPTTAG_ZFILTER<NN>
Defines: Coefficients 0-15 for V (vertical) axis filter (<NN> stands for any number 0-15).
Value type: integer (0-255)
Default value: 0
OPTTAG_FILTERNUM
OPTTAG_FILTERNUM
Defines: a particular filter kernel (frequency amplification profile) applied in the frequency domain of the Feldkamp filtering phase.
Value type: integer
Default value: 1 (Shepp-Logan)
PARTAG_BHFACTOR<N>
PARTAG_BHFACTOR<N>
Defines: a simple beam-hardening correction. <N> stands for indexes 0-3 of coefficients determining a polynomial pre-distortion of logged attenuation signal
Value type: float
Default value: 0
OPTTAG_PROTRUSIONCMODE
OPTTAG_PROTRUSIONCMODE
Defines: COBRA’s protrusion correction algorithm. Tag can have 3 different values, 0, 1 and 2. When it is set to 0, there will be no protrusion correction. Mode 1 assumes that image is linearly decaying outside the detector field of view. Mode 2 assumes that the object has nearly cylindrical shape and a non-linear arch-shape function is used for the extrapolation.
Value type: integer (0-2)
Default value: 1
PARTAG_SCATTERCORRFACTOR_P<N>
PARTAG_SCATTERCORRFACTOR_P<N>
Internal COBRA use (reserved)