correct — Data correction
#include <libprocess/gwyprocess.h>
void (*GwyCoordTransform2DFunc) (gdouble x
,gdouble y
,gdouble *px
,gdouble *py
,gpointer user_data
);
The type of twodimensional coordinate transform function.
x 
Old x coordinate. 

y 
Old y coordinate. 

px 
Location to store new x coordinate. 

py 
Location to store new y coordinate. 

user_data 
User data passed to the caller function. 
Since: 2.5
void gwy_data_field_laplace_solve (GwyDataField *field
,GwyDataField *mask
,gint grain_id
,gdouble qprec
);
Replaces masked areas by the solution of Laplace equation.
The boundary conditions on mask boundaries are Dirichlet with values given by pixels on the outer boundary of the
masked area. Boundary conditions at field edges are Neumann conditions ∂z/∂n=0 where n denotes the normal to the
edge. If entire area of field
is to be replaced the problem is underspecified; field
will be filled with zeros.
For the default value of qprec
the the result should be good enough for any image processing purposes with the
typical local error of order 10⁻⁵ for very large grains and possibly much smaller for small grains. You can lower
qprec
down to about 0.3 or even 0.2 if speed is crucial and some precision can be sacrificed. Below that the
result just starts becoming somewhat worse for not much speed increase. Conversely, you may wish to increase
qprec
up to 3 or even 5 if accuracy is important and you can afford the increased computation time.
field 
A twodimensional data field. 

mask 
A twodimensional data field containing mask defining the areas to interpolate. 

grain_id 
The id number of the grain to replace with the solution of Laplace equation, from 1 to 

qprec 
Speedaccuracy tuning parameter. Pass 1.0 for the default that is fast and sufficiently precise. 
Since: 2.47
void gwy_data_field_correct_laplace_iteration (GwyDataField *data_field
,GwyDataField *mask_field
,GwyDataField *buffer_field
,gdouble corrfactor
,gdouble *error
);
Performs one interation of Laplace data correction.
Tries to remove all the points in mask off the data by using iterative method similar to solving heat flux equation.
Use this function repeatedly until reasonable error
is reached.
gwy_data_field_laplace_solve()
which
is simultaneously much faster and more accurate.data_field 
Data field to be corrected. 

mask_field 
Mask of places to be corrected. 

buffer_field 
Initialized to same size as mask and data. 

error 
Maximum change within last step. 

corrfactor 
Correction factor within step. 
void gwy_data_field_correct_average (GwyDataField *data_field
,GwyDataField *mask_field
);
Fills data under mask with the average value.
This function simply puts average value of all the data_field
values (both masked and unmasked) into points in
data_field
lying under points where mask_field
values are nonzero.
In most cases you probably want to use gwy_data_field_correct_average_unmasked()
instead.
data_field 
A data field. 

mask_field 
Mask of places to be corrected. 
void gwy_data_field_correct_average_unmasked (GwyDataField *data_field
,GwyDataField *mask_field
);
Fills data under mask with the average value of unmasked data.
This function calculates the average value of all unmasked pixels in data_field
and then fills all the masked
pixels with this average value. It is useful as the first rough step of correction of data under the mask.
If all data are masked the field is filled with zeroes.
data_field 
A data field. 

mask_field 
Mask of places to be corrected. 
Since: 2.44
void gwy_data_field_mask_outliers (GwyDataField *data_field
,GwyDataField *mask_field
,gdouble thresh
);
Creates mask of data that are above or below thresh
*sigma from average height.
Sigma denotes rootmean square deviation of heights. This criterium corresponds to the usual Gaussian distribution
outliers detection if thresh
is 3.
data_field 
A data field. 

mask_field 
A data field to be filled with mask. 

thresh 
Threshold value. 
void gwy_data_field_mask_outliers2 (GwyDataField *data_field
,GwyDataField *mask_field
,gdouble thresh_low
,gdouble thresh_high
);
Creates mask of data that are above or below multiples of rms from average height.
Data that are below mean
thresh_low
*sigma
or above mean
+thresh_high
*sigma
are marked as outliers, where
sigma
denotes the rootmean square deviation of heights.
data_field 
A data field. 

mask_field 
A data field to be filled with mask. 

thresh_low 
Lower threshold value. 

thresh_high 
Upper threshold value. 
Since: 2.26
void gwy_data_field_distort (GwyDataField *source
,GwyDataField *dest
,GwyCoordTransform2DFunc invtrans
,gpointer user_data
,GwyInterpolationType interp
,GwyExteriorType exterior
,gdouble fill_value
);
Distorts a data field in the horizontal plane.
Note the transform function invtrans
is the inverse transform, in other words it calculates the old coordinates
from the new coordinates (the transform would not be uniquely defined the other way round).
The GWY_EXTERIOR_LAPLACE
exterior type cannot be used with this function.
source 
Source data field. 

dest 
Destination data field. 

invtrans 
Inverse transform function, that is the transformation from new coordinates to old coordinates. It
gets ( 

user_data 
Pointer passed as 

interp 
Interpolation type to use. 

exterior 
Exterior pixels handling. 

fill_value 
The value to use with 
Since: 2.5
void gwy_data_field_sample_distorted (GwyDataField *source
,GwyDataField *dest
,const GwyXY *coords
,GwyInterpolationType interp
,GwyExteriorType exterior
,gdouble fill_value
);
Resamples a data field in an arbitrarily distorted manner.
Each item in coords
corresponds to one pixel in dest
and gives the coordinates in source
defining the value to
set in this pixel.
The GWY_EXTERIOR_LAPLACE
exterior type cannot be used with this function.
source 
Source data field. 

dest 
Destination data field. 

coords 
Array of 

interp 
Interpolation type to use. 

exterior 
Exterior pixels handling. 

fill_value 
The value to use with 
Since: 2.45
void gwy_data_field_affine (GwyDataField *source
,GwyDataField *dest
,const gdouble *invtrans
,GwyInterpolationType interp
,GwyExteriorType exterior
,gdouble fill_value
);
Performs an affine transformation of a data field in the horizontal plane.
Note the transform invtrans
is the inverse transform, in other words it calculates the old coordinates from the
new coordinates. This way even degenerate (noninvertible) transforms can be meaningfully used. Also note that the
(column, row) coordinate system is lefthanded.
The GWY_EXTERIOR_LAPLACE
exterior type cannot be used with this function.
source 
Source data field. 

dest 
Destination data field. 

invtrans 
Inverse transform, that is the transformation from new pixel coordinates to old pixel coordinates,
represented as ( 

interp 
Interpolation type to use. 

exterior 
Exterior pixels handling. 

fill_value 
The value to use with 
Since: 2.34
void gwy_data_field_affine_prepare (GwyDataField *source
,GwyDataField *dest
,const gdouble *a1a2
,gdouble *a1a2_corr
,gdouble *invtrans
,GwyAffineScalingType scaling
,gboolean prevent_rotation
,gdouble oversampling
);
Resolves an affine transformation of a data field in the horizontal plane.
This function calculates suitable arguments for gwy_data_field_affine()
from given images and lattice vectors (in
real coordinates).
Data field dest
will be resized and its real dimensions and units set in anticipation of gwy_data_field_affine()
.
Its contents will be destroyed.
Note that a1a2_corr
is an inputoutput parameter. In general, the vectors will be modified according to scaling
and prevent_rotation
to the actual vectors in dest
after the transformation. Only if prevent_rotation
is FALSE
and scaling
is GWY_AFFINE_SCALING_AS_GIVEN
the vectors are preserved.
source 
Source data field. 

dest 
Destination data field. 

a1a2 
Lattice vectors (or generally base vectors) in 

a1a2_corr 
Correct lattice vectors (or generally base vectors) 

invtrans 
Inverse transform as an array of six values to be filled according to 

scaling 
How (or if) to scale the correct lattice vectors. 

prevent_rotation 


oversampling 
Oversampling factor. Values larger than 1 mean smaller pixels (and more of them) in 
Since: 2.49
gboolean gwy_data_field_measure_lattice_acf (GwyDataField *acf2d
,gdouble *a1a2
);
Estimates or improves estimate of lattice vectors from a 2D ACF field.
Note that the 2D ACF of a data field has to be passed, not the data field itself. The correlation function can be
for instance calculated by gwy_data_field_2dacf()
. However, you can calculate and/or process the correlation
function in any way you see fit.
When the vectors in a1a2
are zero the function attempts to estimate the lattice from scratch. But if a1a2
contains two nonzero vectors it takes them as approximate lattice vectors to improve.
If the function return FALSE
the array a1a2
is filled with useless values and must be ignored.
acf2d 
Data field containing twodimensional autocorrelation function. 

a1a2 
Lattice vectors as an array of four components: 
TRUE
if good lattice vectors were found, FALSE
on failure.
Since: 2.49
gboolean gwy_data_field_measure_lattice_psdf (GwyDataField *psdf2d
,gdouble *a1a2
);
Estimates or improves estimate of lattice vectors from a 2D PSDF field.
Note that the 2D PSDF of a data field has to be passed, not the data field itself. The spectral density can be for
instance calculated by gwy_data_field_2dfft()
and summing the squares of real and imaginary parts However, you can
calculate and/or process the spectral density in any way you see fit.
When the vectors in a1a2
are zero the function attempts to estimate the lattice from scratch. But if a1a2
contains two nonzero vectors it takes them as approximate lattice vectors to improve.
If the function return FALSE
the array a1a2
is filled with useless values and must be ignored.
psdf2d 
Data field containing twodimensional power spectrum density function (or alternatively Fourier coefficient modulus). 

a1a2 
Lattice vectors as an array of four components: 
TRUE
if good lattice vectors were found, FALSE
on failure.
Since: 2.49
gboolean gwy_data_line_correct_laplace (GwyDataLine *data_line
,GwyDataLine *mask_line
);
Fills missing values in a data line using Laplace data correction.
Both data lines must have the same number of values.
For onedimensional data the missing data interpolation is explicit. Interior missing segments are filled with linear dependence between the edge points. Missing segments with one end open are filled with the edge value.
data_line 
A data line. 

mask_line 
Mask of places to be corrected. 
TRUE
if the line contained any data at all. If there are no data the FALSE
is returned and data_line
is filled with zeros.
Since: 2.45
void gwy_data_field_mark_scars (GwyDataField *data_field
,GwyDataField *result
,gdouble threshold_high
,gdouble threshold_low
,gdouble min_scar_len
,gdouble max_scar_width
,gboolean negative
);
Find and marks scars in a data field.
Scars are linear horizontal defects, consisting of shifted values. Zero or negative values in result
siginify
normal data, positive values siginify samples that are part of a scar.
data_field 
A data field to find scars in. 

result 
A data field to store the result to (it is resized to match 

threshold_high 
Miminum relative step for scar marking, must be positive. 

threshold_low 
Definite relative step for scar marking, must be at least equal to 

min_scar_len 
Minimum length of a scar, shorter ones are discarded (must be at least one). 

max_scar_width 
Maximum width of a scar, must be at least one. 

negative 
Since: 2.46
void gwy_data_field_subtract_row_shifts (GwyDataField *data_field
,GwyDataLine *shifts
);
Shifts entire data field rows as specified by given data line.
Data line shifts
must have resolution corresponding to the number of data_field
rows. Its values are subtracted
from individual field rows.
data_field 
A data field. 

shifts 
Data line containing the row shifts. 
Since: 2.52
GwyDataLine * gwy_data_field_find_row_shifts_trimmed_mean (GwyDataField *data_field
,GwyDataField *mask
,GwyMaskingType masking
,gdouble trimfrac
,gint mincount
);
Finds row shifts to misaligned row correction using trimmed row means.
For zero trimfrac
the function calculates row means. For trimfrac
of 1/2 or larger it calculates row medians.
Values between correspond to trimmed means.
data_field 
A data field. 

mask 
Mask of values to take values into account/exclude, or 

masking 
Masking mode to use. See the introduction for description of masking modes. 

trimfrac 
Fraction of lowest values and highest values to discard when trimming. 

mincount 
Minimum number of values in a row necessary for perrow calculation. Rows which are essentially completely masked are not shifted with respect to a global value. Pass a nonpositive number to use an automatic minimum count. 
A newly created data line containing the row shifts, for instance row means, medians or trimmed means.
Since: 2.52
GwyDataLine * gwy_data_field_find_row_shifts_trimmed_diff (GwyDataField *data_field
,GwyDataField *mask
,GwyMaskingType masking
,gdouble trimfrac
,gint mincount
);
Finds row shifts to misaligned row correction using trimmed means of row differences.
For zero trimfrac
the function calculates row means. For trimfrac
of 1/2 or larger it calculates row medians.
Values between correspond to trimmed means.
data_field 
A data field. 

mask 
Mask of values to take values into account/exclude, or 

masking 
Masking mode to use. See the introduction for description of masking modes. 

trimfrac 
Fraction of lowest values and highest values to discard when trimming. 

mincount 
Minimum number of values in a row necessary for perrow calculation. Rows which are essentially completely masked are not shifted with respect to a global value. Pass a nonpositive number to use an automatic minimum count. 
A newly created data line containing the row shifts, for instance row means, medians or trimmed means.
Since: 2.52
GwyPlaneSymmetry gwy_data_field_unrotate_find_corrections (GwyDataLine *derdist
,gdouble *correction
);
Finds rotation corrections.
Rotation correction is computed for for all symmetry types. In addition an estimate is made about the prevalent one.
derdist 
Angular derivation distribution (normally obrained from 

correction 
Corrections for particular symmetry types will be stored here (indexed by GwyPlaneSymmetry).

The estimate type of prevalent symmetry.