libvips/include/vips/yafrsmooth.h

108 lines
3.9 KiB
C

/* YAFRSMOOTH interpolator.
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
#ifndef VIPS_YAFRSMOOTH_H
#define VIPS_YAFRSMOOTH_H
#ifdef __cplusplus
extern "C" {
#endif /*__cplusplus*/
#define VIPS_TYPE_INTERPOLATE_YAFRSMOOTH \
(vips_interpolate_yafrsmooth_get_type())
#define VIPS_INTERPOLATE_YAFRSMOOTH( obj ) \
(G_TYPE_CHECK_INSTANCE_CAST( (obj), \
VIPS_TYPE_INTERPOLATE_YAFRSMOOTH, VipsInterpolateYafrsmooth ))
#define VIPS_INTERPOLATE_YAFRSMOOTH_CLASS( klass ) \
(G_TYPE_CHECK_CLASS_CAST( (klass), \
VIPS_TYPE_INTERPOLATE_YAFRSMOOTH, VipsInterpolateYafrsmoothClass))
#define VIPS_IS_INTERPOLATE_YAFRSMOOTH( obj ) \
(G_TYPE_CHECK_INSTANCE_TYPE( (obj), VIPS_TYPE_INTERPOLATE_YAFRSMOOTH ))
#define VIPS_IS_INTERPOLATE_YAFRSMOOTH_CLASS( klass ) \
(G_TYPE_CHECK_CLASS_TYPE( (klass), VIPS_TYPE_INTERPOLATE_YAFRSMOOTH ))
#define VIPS_INTERPOLATE_YAFRSMOOTH_GET_CLASS( obj ) \
(G_TYPE_INSTANCE_GET_CLASS( (obj), \
VIPS_TYPE_INTERPOLATE_YAFRSMOOTH, VipsInterpolateYafrsmoothClass ))
typedef struct _VipsInterpolateYafrsmooth {
VipsInterpolate parent_object;
/* "sharpening" is a continuous method parameter which is
* proportional to the amount of "diagonal straightening" which the
* nonlinear correction part of the method may add to the underlying
* linear scheme. You may also think of it as a sharpening
* parameter: higher values correspond to more sharpening, and
* negative values lead to strange looking effects.
*
* The default value is sharpening = 29/32 when the scheme being
* "straightened" is Catmull-Rom---as is the case here. This value
* fixes key pixel values near the diagonal boundary between two
* monochrome regions (the diagonal boundary pixel values being set
* to the halfway colour).
*
* If resampling seems to add unwanted texture artifacts, push
* sharpening toward 0. It is not generally not recommended to set
* sharpening to a value larger than 4.
*
* Sharpening is halved because the .5 which has to do with the
* relative coordinates of the evaluation points (which has to do
* with .5*rite_width etc) is folded into the constant to save
* flops. Consequently, the largest recommended value of
* sharpening_over_two is 2=4/2.
*
* In order to simplify interfacing with users, the parameter which
* should be set by the user is normalized so that user_sharpening =
* 1 when sharpening is equal to the recommended value. Consistently
* with the above discussion, values of user_sharpening between 0
* and about 3.625 give good results.
*/
double sharpening;
} VipsInterpolateYafrsmooth;
typedef struct _VipsInterpolateYafrsmoothClass {
VipsInterpolateClass parent_class;
} VipsInterpolateYafrsmoothClass;
GType vips_interpolate_yafrsmooth_get_type( void );
VipsInterpolate *vips_interpolate_yafrsmooth_new( void );
void vips_interpolate_yafrsmooth_set_sharpening( VipsInterpolateYafrsmooth *,
double sharpening );
/* Convenience: return a static default yafrsmooth, so no need to free it.
*/
VipsInterpolate *vips_interpolate_yafrsmooth_static( void );
#ifdef __cplusplus
}
#endif /*__cplusplus*/
#endif /*VIPS_YAFRSMOOTH_H*/