VipsInterpolate

VipsInterpolate — various interpolators: nearest, bilinear, and some non-linear

Stability Level

Stable, unless otherwise indicated

Object Hierarchy

    GObject
    ╰── VipsObject
        ╰── VipsInterpolate

Includes

#include <vips/vips.h>

Description

A number of image interpolators.

Functions

VipsInterpolateMethod ()

void
(*VipsInterpolateMethod) (VipsInterpolate *interpolate,
                          void *out,
                          VipsRegion *in,
                          double x,
                          double y);

An interpolation function. It should read source pixels from in with VIPS_REGION_ADDR(), it can look left and up from (x, y) by window_offset pixels and it can access pixels in a window of size window_size .

The interpolated value should be written to the pixel pointed to by out .

See also: VipsInterpolateClass.

Parameters

interpolate

the interpolator

 

out

write the interpolated pixel here

 

in

read source pixels from here

 

x

interpolate value at this position

 

y

interpolate value at this position

 

vips_interpolate ()

void
vips_interpolate (VipsInterpolate *interpolate,
                  void *out,
                  VipsRegion *in,
                  double x,
                  double y);

Look up the interpolate method in the class and call it. Use vips_interpolate_get_method() to get a direct pointer to the function and avoid the lookup overhead.

You need to set in and out up correctly.

Parameters

interpolate

interpolator to use

 

out

write result here

 

in

read source data from here

 

x

interpolate value at this position

 

y

interpolate value at this position

 

vips_interpolate_get_method ()

VipsInterpolateMethod
vips_interpolate_get_method (VipsInterpolate *interpolate);

Look up the interpolate method in the class and return it. Use this instead of vips_interpolate() to cache method dispatch.

Parameters

interpolate

interpolator to use

 

Returns

a pointer to the interpolation function


vips_interpolate_get_window_size ()

int
vips_interpolate_get_window_size (VipsInterpolate *interpolate);

Look up an interpolators desired window size.

Parameters

interpolate

interpolator to use

 

Returns

the interpolators required window size


vips_interpolate_get_window_offset ()

int
vips_interpolate_get_window_offset (VipsInterpolate *interpolate);

Look up an interpolators desired window offset.

Parameters

interpolate

interpolator to use

 

Returns

the interpolators required window offset


VIPS_TRANSFORM_SHIFT

#define VIPS_TRANSFORM_SHIFT (6)

Many of the vips interpolators use fixed-point arithmetic for coordinate calculation. This is how many bits of precision they use.


VIPS_TRANSFORM_SCALE

#define VIPS_TRANSFORM_SCALE (1 << VIPS_TRANSFORM_SHIFT)

VIPS_TRANSFORM_SHIFT as a multiplicative constant.


VIPS_INTERPOLATE_SHIFT

#define VIPS_INTERPOLATE_SHIFT (12)

Many of the vips interpolators use fixed-point arithmetic for value calcualtion. This is how many bits of precision they use.


VIPS_INTERPOLATE_SCALE

#define VIPS_INTERPOLATE_SCALE (1 << VIPS_INTERPOLATE_SHIFT)

VIPS_INTERPOLATE_SHIFT as a multiplicative constant.


vips_interpolate_nearest_static ()

VipsInterpolate *
vips_interpolate_nearest_static (void);

A convenience function that returns a nearest-neighbour interpolator you don't need to free.

Returns

a nearest-neighbour interpolator.

[transfer none]


vips_interpolate_bilinear_static ()

VipsInterpolate *
vips_interpolate_bilinear_static (void);

A convenience function that returns a bilinear interpolator you don't need to free.

Returns

a bilinear interpolator.

[transfer none]


vips_interpolate_new ()

VipsInterpolate *
vips_interpolate_new (const char *nickname);

Look up an interpolator from a nickname and make one. You need to free the result with g_object_unref() when you're done with it.

See also: vips_type_find().

Parameters

nickname

nickname for interpolator

 

Returns

an interpolator, or NULL on error.

Types and Values