DWT: Gwyddion Library Reference Manual

## DWT DWT — Discrete Wavelet Transform |

## Functions

const GwyEnum * | gwy_dwt_type_get_enum ()
const GwyEnum * | gwy_dwt_denoise_type_get_enum ()
GwyLine * | gwy_dwt_set_coefficients ()
void | gwy_line_dwt ()
void | gwy_field_xdwt ()
void | gwy_field_ydwt ()
void | gwy_field_dwt ()
void | gwy_field_dwt_mark_anisotropy ()

## Types and Values

enum | GwyDWTType
enum | GwyDWTDenoiseType

## Includes

    #include <libgwyddion/gwyddion.h>

## Description

## Functions

### gwy_dwt_type_get_enum()

    const GwyEnum *
    gwy_dwt_type_get_enum (void);

Returns GwyEnum for GwyDWTType enum type.

#### Returns

`NULL`-terminated GwyEnum which must not be modified nor freed.

### gwy_dwt_denoise_type_get_enum()

    const GwyEnum *
    gwy_dwt_denoise_type_get_enum (void);

Returns GwyEnum for GwyDWTDenoiseType enum type.

#### Returns

`NULL`-terminated GwyEnum which must not be modified nor freed.

### gwy_dwt_set_coefficients()

    GwyLine *
    gwy_dwt_set_coefficients (GwyLine *dline,
                              GwyDWTType type);

Fills resampled or nely allocated data line with wavelet coefficients.

#### Parameters

dline | Data line to store wavelet coefficients to (or `NULL` to allocate a new one). | [nullable]
type | Wavelet type. |

#### Returns

resampled or newly allocated GwyLine with wavelet coefficients.

[transfer none]

### gwy_line_dwt()

    void
    gwy_line_dwt (GwyLine *dline,
                  GwyLine *wt_coefs,
                  GwyTransformDirection direction,
                  gint minsize);

Performs steps of the wavelet decomposition.

The smallest low pass coefficients block is equal to `minsize` . Run with `minsize` = `dline->res` /2 to perform one step of decomposition or `minsize` = 4 to perform full decomposition (or anything between).

#### Parameters

dline | Data line to be transformed, it must have at least four samples. |
wt_coefs | Data line where the wavelet transform coefficients are stored. |
direction | Transform direction. |
minsize | size of minimal transform result block |

### gwy_field_xdwt()

    void
    gwy_field_xdwt (GwyField *field,
                    GwyLine *wt_coefs,
                    GwyTransformDirection direction,
                    gint minsize);

Performs steps of the X-direction image wavelet decomposition.

The smallest low pass coefficients block is equal to `minsize` . Run with `minsize` = `field->xres` /2 to perform one step of decomposition or `minsize` = 4 to perform full decomposition (or anything between).

#### Parameters

field | Data field to be transformed. |
wt_coefs | Data line where the wavelet transform coefficients are stored. |
direction | Transform direction. |
minsize | size of minimal transform result block |

### gwy_field_ydwt()

    void
    gwy_field_ydwt (GwyField *field,
                    GwyLine *wt_coefs,
                    GwyTransformDirection direction,
                    gint minsize);

Performs steps of the Y-direction image wavelet decomposition.

The smallest low pass coefficients block is equal to `minsize` . Run with `minsize` = `field->yres` /2 to perform one step of decomposition or `minsize` = 4 to perform full decomposition (or anything between).

#### Parameters

field | Data field to be transformed. |
wt_coefs | Data line where the wavelet transform coefficients are stored. |
direction | Transform direction. |
minsize | size of minimal transform result block |

### gwy_field_dwt()

    void
    gwy_field_dwt (GwyField *field,
                   GwyLine *wt_coefs,
                   GwyTransformDirection direction,
                   gint minsize);

Performs steps of the 2D image wavelet decomposition.

The smallest low pass coefficients block is equal to `minsize` . Run with `minsize` = `field->xres` /2 to perform one step of decomposition or `minsize` = 4 to perform full decomposition (or anything between).

#### Parameters

field | Data field to be transformed (must be square). |
wt_coefs | Data line where the wavelet transform coefficients are stored. |
direction | Transform direction. |
minsize | size of minimal transform result block |

### gwy_field_dwt_mark_anisotropy()

    void
    gwy_field_dwt_mark_anisotropy (GwyField *field,
                                   GwyNield *mask,
                                   GwyLine *wt_coefs,
                                   gdouble ratio,
                                   gint lowlimit);

Performs steps of the 2D image wavelet decomposition.

The smallest low pass coefficients block is equal to `minsize` . Run with `minsize` = `field->xres` /2 to perform one step of decomposition or `minsize` = 4 to perform full decomposition (or anything between).

#### Parameters

field | Data field to mark anisotropy of (must be square). |
mask | Number field to fill with the output mask. |
wt_coefs | Data line to store wavelet transform coefficients to. |
ratio | Anisotropy threshold. |
lowlimit | Size of minimal transform result block. |

## Types and Values

### enum GwyDWTType

#### Members

GWY_DWT_HAAR |  |
GWY_DWT_DAUB4 |  |
GWY_DWT_DAUB6 |  |
GWY_DWT_DAUB8 |  |
GWY_DWT_DAUB12 |  |
GWY_DWT_DAUB20 |  |

### enum GwyDWTDenoiseType

#### Members

GWY_DWT_DENOISE_UNIVERSAL |  |
GWY_DWT_DENOISE_SCALE_ADAPTIVE |  |
GWY_DWT_DENOISE_SPACE_ADAPTIVE |  |