correct

correct — Data correction

Functions

Includes

#include <libprocess/gwyprocess.h>

Description

Functions

GwyCoordTransform2DFunc ()

void
(*GwyCoordTransform2DFunc) (gdouble x,
                            gdouble y,
                            gdouble *px,
                            gdouble *py,
                            gpointer user_data);

The type of two-dimensional coordinate transform function.

Parameters

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


gwy_data_field_correct_laplace_iteration ()

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.

Parameters

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.

 

gwy_data_field_correct_average ()

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.

Parameters

data_field

A data field.

 

mask_field

Mask of places to be corrected.

 

gwy_data_field_correct_average_unmasked ()

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.

Parameters

data_field

A data field.

 

mask_field

Mask of places to be corrected.

 

Since: 2.44


gwy_data_field_mask_outliers ()

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 root-mean square deviation of heights. This criterium corresponds to the usual Gaussian distribution outliers detection if thresh is 3.

Parameters

data_field

A data field.

 

mask_field

A data field to be filled with mask.

 

thresh

Threshold value.

 

gwy_data_field_mask_outliers2 ()

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 root-mean square deviation of heights.

Parameters

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


gwy_data_field_distort ()

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).

Parameters

source

Source data field.

 

dest

Destination data field.

 

invtrans

Inverse transform function, that is the transformation from new coordinates to old coordinates. It gets (j +0.5, i +0.5), where i and j are the new row and column indices, passed as the input coordinates. The output coordinates should follow the same convention. Unless a special exterior handling is required, the transform function does not need to concern itself with coordinates being outside of the data.

 

user_data

Pointer passed as user_data to invtrans .

 

interp

Interpolation type to use.

 

exterior

Exterior pixels handling.

 

fill_value

The value to use with GWY_EXTERIOR_FIXED_VALUE .

 

Since: 2.5


gwy_data_field_sample_distorted ()

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.

Parameters

source

Source data field.

 

dest

Destination data field.

 

coords

Array of source coordinates with the same number of items as dest , ordered as data field data. See gwy_data_field_distort() for coordinate convention discussion.

 

interp

Interpolation type to use.

 

exterior

Exterior pixels handling.

 

fill_value

The value to use with GWY_EXTERIOR_FIXED_VALUE .

 

Since: 2.45


gwy_data_field_affine ()

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 (non-invertible) transforms can be meaningfully used. Also note that the (column, row) coordinate system is left-handed.

Parameters

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 (j +0.5, i +0.5), where i and j are the row and column indices. It is represented as a six-element array [axx , axy , ayx , ayy , bx , by ] where axy is the coefficient from x to y .

 

interp

Interpolation type to use.

 

exterior

Exterior pixels handling.

 

fill_value

The value to use with GWY_EXTERIOR_FIXED_VALUE .

 

Since: 2.34


gwy_data_line_correct_laplace ()

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 one-dimensional 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.

Parameters

data_line

A data line.

 

mask_field

Mask of places to be corrected.

 

Returns

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


gwy_data_field_unrotate_find_corrections ()

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.

Parameters

derdist

Angular derivation distribution (normally obrained from gwy_data_field_slope_distribution()).

 

correction

Corrections for particular symmetry types will be stored here (indexed by GwyPlaneSymmetry). correction [0] contains the most probable correction. All angles are in radians.

 

Returns

The estimate type of prevalent symmetry.

Types and Values