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Filters are point-wise operations, such as thresholding, or generally local operations producing a value based on the data in the vicinity of each point: gradients, step detectors and convolutions. Some simple common point-wise operations, e.g. value inversion, are also found in base GwyDataField methods.
void
gwy_data_field_normalize (GwyDataField *data_field
);
Normalizes data in a data field to range 0.0 to 1.0.
It is equivalent to gwy_data_field_renormalize(data_field
, 1.0, 0.0);
If data_field
is filled with only one value, it is changed to 0.0.
void gwy_data_field_renormalize (GwyDataField *data_field
,gdouble range
,gdouble offset
);
Transforms data in a data field with first linear function to given range.
When range
is positive, the new data range is (offset
, offset
+range
);
when range
is negative, the new data range is (offset
-range
, offset
).
In neither case the data are flipped, negative range only means different
selection of boundaries.
When range
is zero, this method is equivalent to
gwy_data_field_fill(data_field
, offset
).
gint gwy_data_field_threshold (GwyDataField *data_field
,gdouble threshval
,gdouble bottom
,gdouble top
);
Tresholds values of a data field.
Values smaller than threshold
are set to value bottom
, values higher
than threshold
or equal to it are set to value top
gint gwy_data_field_area_threshold (GwyDataField *data_field
,gint col
,gint row
,gint width
,gint height
,gdouble threshval
,gdouble bottom
,gdouble top
);
Tresholds values of a rectangular part of a data field.
Values smaller than threshold
are set to value bottom
, values higher
than threshold
or equal to it are set to value top
gint gwy_data_field_clamp (GwyDataField *data_field
,gdouble bottom
,gdouble top
);
Limits data field values to a range.
gint gwy_data_field_area_clamp (GwyDataField *data_field
,gint col
,gint row
,gint width
,gint height
,gdouble bottom
,gdouble top
);
Limits values in a rectangular part of a data field to a range.
void gwy_data_field_area_gather (GwyDataField *data_field
,GwyDataField *result
,GwyDataField *buffer
,gint hsize
,gint vsize
,gboolean average
,gint col
,gint row
,gint width
,gint height
);
Sums or averages values in reactangular areas around each sample in a data field.
When the gathered area extends out of calculation area, only samples from their intersection are taken into the local sum (or average).
There are no restrictions on values of hsize
and vsize
with regard to
width
and height
, but they have to be positive.
The result is calculated by the means of two-dimensional rolling sums.
One one hand it means the calculation time depends linearly on
(width
+ hsize
)*(height
+ vsize
) instead of
width
*hsize
*height
*vsize
. On the other hand it means absolute rounding
errors of all output values are given by the largest input values, that is
relative precision of results small in absolute value may be poor.
data_field |
A data field. |
|
result |
A data field to put the result to, it may be |
|
buffer |
A data field to use as a scratch area, its size must be at least
|
|
col |
Upper-left column coordinate. |
|
row |
Upper-left row coordinate. |
|
width |
Area width (number of columns). |
|
height |
Area height (number of rows). |
|
hsize |
Horizontal size of gathered area. The area is centered around
each sample if |
|
vsize |
Vertical size of gathered area. The area is centered around
each sample if |
|
average |
|
void gwy_data_field_convolve (GwyDataField *data_field
,GwyDataField *kernel_field
);
Convolves a data field with given kernel.
void gwy_data_field_area_convolve (GwyDataField *data_field
,GwyDataField *kernel_field
,gint col
,gint row
,gint width
,gint height
);
Convolves a rectangular part of a data field with given kernel.
data_field |
A data field to convolve. It must be at least as large as
1/3 of |
|
kernel_field |
Kenrel field to convolve |
|
col |
Upper-left column coordinate. |
|
row |
Upper-left row coordinate. |
|
width |
Area width (number of columns). |
|
height |
Area height (number of rows). |
void gwy_data_field_convolve_1d (GwyDataField *data_field
,GwyDataLine *kernel_line
,GwyOrientation orientation
);
Convolves a data field with given linear kernel.
data_field |
A data field to convolve. It must be at least as large as
1/3 of |
|
kernel_line |
Kenrel line to convolve |
|
orientation |
Filter orientation (see |
Since: 2.4
void gwy_data_field_area_convolve_1d (GwyDataField *data_field
,GwyDataLine *kernel_line
,GwyOrientation orientation
,gint col
,gint row
,gint width
,gint height
);
Convolves a rectangular part of a data field with given linear kernel.
For large separable kernels it can be more efficient to use a sequence of horizontal and vertical convolutions instead one 2D convolution.
data_field |
A data field to convolve. It must be at least as large as
1/3 of |
|
kernel_line |
Kernel line to convolve |
|
orientation |
Filter orientation ( |
|
col |
Upper-left column coordinate. |
|
row |
Upper-left row coordinate. |
|
width |
Area width (number of columns). |
|
height |
Area height (number of rows). |
Since: 2.4
void gwy_data_field_filter_median (GwyDataField *data_field
,gint size
);
Filters a data field with median filter.
void gwy_data_field_area_filter_median (GwyDataField *data_field
,gint size
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with median filter.
void gwy_data_field_filter_mean (GwyDataField *data_field
,gint size
);
Filters a data field with mean filter of size size
.
void gwy_data_field_area_filter_mean (GwyDataField *data_field
,gint size
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with mean filter of size size
.
This method is a simple gwy_data_field_area_gather()
wrapper.
void gwy_data_field_filter_conservative (GwyDataField *data_field
,gint size
);
Filters a data field with conservative denoise filter.
void gwy_data_field_area_filter_conservative (GwyDataField *data_field
,gint size
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with conservative denoise filter.
void
gwy_data_field_filter_laplacian (GwyDataField *data_field
);
Filters a data field with Laplacian filter.
void gwy_data_field_area_filter_laplacian (GwyDataField *data_field
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with Laplacian filter.
void
gwy_data_field_filter_laplacian_of_gaussians
(GwyDataField *data_field
);
Filters a data field with Laplacian of Gaussians filter.
Since: 2.23
void gwy_data_field_area_filter_laplacian_of_gaussians (GwyDataField *data_field
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with Laplacian of Gaussians filter.
data_field |
A data field to apply the filter to. |
|
col |
Upper-left column coordinate. |
|
row |
Upper-left row coordinate. |
|
width |
Area width (number of columns). |
|
height |
Area height (number of rows). |
Since: 2.23
void gwy_data_field_filter_sobel (GwyDataField *data_field
,GwyOrientation orientation
);
Filters a data field with a directional Sobel filter.
void gwy_data_field_area_filter_sobel (GwyDataField *data_field
,GwyOrientation orientation
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with a directional Sobel filter.
void
gwy_data_field_filter_sobel_total (GwyDataField *data_field
);
Filters a data field with total Sobel filter.
Since: 2.31
void gwy_data_field_filter_prewitt (GwyDataField *data_field
,GwyOrientation orientation
);
Filters a data field with Prewitt filter.
void gwy_data_field_area_filter_prewitt (GwyDataField *data_field
,GwyOrientation orientation
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with a directional Prewitt filter.
void
gwy_data_field_filter_prewitt_total (GwyDataField *data_field
);
Filters a data field with total Prewitt filter.
Since: 2.31
void gwy_data_field_filter_slope (GwyDataField *data_field
,GwyDataField *xder
,GwyDataField *yder
);
Calculates x and y derivaties for an entire field.
The derivatives are calculated as the simple symmetrical differences (in physical units, not pixel-wise), except at the edges where the differences are one-sided.
Since: 2.37
void
gwy_data_field_filter_dechecker (GwyDataField *data_field
);
Filters a data field with 5x5 checker pattern removal filter.
Since: 2.1
void gwy_data_field_area_filter_dechecker (GwyDataField *data_field
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with 5x5 checker pattern removal filter.
data_field |
A data field to apply the filter to. |
|
col |
Upper-left column coordinate. |
|
row |
Upper-left row coordinate. |
|
width |
Area width (number of columns). |
|
height |
Area height (number of rows). |
Since: 2.1
void gwy_data_field_filter_gaussian (GwyDataField *data_field
,gdouble sigma
);
Filters a data field with a Gaussian filter.
data_field |
A data field to apply the filter to. |
|
sigma |
The sigma parameter of the Gaussian. |
Since: 2.4
void gwy_data_field_area_filter_gaussian (GwyDataField *data_field
,gdouble sigma
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with a Gaussian filter.
The Gausian is normalized, i.e. it is sum-preserving.
data_field |
A data field to apply the filter to. |
|
sigma |
The sigma parameter of the Gaussian. |
|
col |
Upper-left column coordinate. |
|
row |
Upper-left row coordinate. |
|
width |
Area width (number of columns). |
|
height |
Area height (number of rows). |
Since: 2.4
void gwy_data_field_filter_minimum (GwyDataField *data_field
,gint size
);
Filters a data field with minimum filter.
void gwy_data_field_area_filter_minimum (GwyDataField *data_field
,gint size
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with minimum filter.
This operation is often called erosion filter.
void gwy_data_field_filter_maximum (GwyDataField *data_field
,gint size
);
Filters a data field with maximum filter.
void gwy_data_field_area_filter_maximum (GwyDataField *data_field
,gint size
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with maximum filter.
This operation is often called dilation filter.
void gwy_data_field_area_filter_min_max (GwyDataField *data_field
,GwyDataField *kernel
,GwyMinMaxFilterType filtertype
,gint col
,gint row
,gint width
,gint height
);
Applies a morphological operation with a flat structuring element to a part of a data field.
Morphological operations with flat structuring elements can be expressed using minimum (erosion) and maximum (dilation) filters that are the basic operations this function can perform.
The kernel field is a mask that defines the shape of the flat structuring
element. It is reflected for all maximum operations (dilation). For
symmetrical kernels this does not matter. You can use
gwy_data_field_elliptic_area_fill()
to create a true circular (or
elliptical) kernel.
The kernel is implicitly centered, i.e. it will be applied symmetrically to avoid unexpected data movement. Even-sized kernels (generally not recommended) will extend farther towards the top left image corner for minimum (erosion) and towards the bottom right corner for maximum (dilation) operations due to the reflection. If you need off-center structuring elements you can add empty rows or columns to one side of the kernel to counteract the symmetrisation.
The operation is linear-time in kernel size for any convex kernel. Note
gwy_data_field_area_filter_minimum()
and
gwy_data_field_area_filter_maximum()
, which are limited to square
structuring elements, are much faster for large sizes of the squares.
The exterior is always handled as GWY_EXTERIOR_BORDER_EXTEND
.
data_field |
A data field to apply the filter to. |
|
kernel |
Data field defining the flat structuring element. |
|
filtertype |
The type of filter to apply. |
|
col |
Upper-left column coordinate. |
|
row |
Upper-left row coordinate. |
|
width |
Area width (number of columns). |
|
height |
Area height (number of rows). |
Since: 2.43
void gwy_data_field_area_filter_disc_asf (GwyDataField *data_field
,gint radius
,gboolean closing
,gint col
,gint row
,gint width
,gint height
);
void gwy_data_field_filter_rms (GwyDataField *data_field
,gint size
);
Filters a data field with RMS filter.
void gwy_data_field_area_filter_rms (GwyDataField *data_field
,gint size
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with RMS filter of size size
.
RMS filter computes root mean square in given area.
void
gwy_data_field_filter_kuwahara (GwyDataField *data_field
);
Filters a data field with Kuwahara filter.
void gwy_data_field_area_filter_kuwahara (GwyDataField *data_field
,gint col
,gint row
,gint width
,gint height
);
Filters a rectangular part of a data field with a Kuwahara (edge-preserving smoothing) filter.
void gwy_data_field_filter_canny (GwyDataField *data_field
,gdouble threshold
);
Filters a rectangular part of a data field with canny edge detector filter.
void gwy_data_field_shade (GwyDataField *data_field
,GwyDataField *target_field
,gdouble theta
,gdouble phi
);
Shades a data field.
void gwy_data_field_filter_harris (GwyDataField *x_gradient
,GwyDataField *y_gradient
,GwyDataField *result
,gint neighbourhood
,gdouble alpha
);