687 lines
23 KiB
C
687 lines
23 KiB
C
/* This file is part of GEGL
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*
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* GEGL is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 3 of the
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* License, or (at your option) any later version.
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*
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* GEGL is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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* Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with GEGL; if not, see
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* <http://www.gnu.org/licenses/>.
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*
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* 2008 (c) Nicolas Robidoux (developer of Yet Another Fast
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* Resampler).
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*
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* Acknowledgement: N. Robidoux's research on YAFR funded in part by
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* an NSERC (National Science and Engineering Research Council of
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* Canada) Discovery Grant.
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*/
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#include <glib-object.h>
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#include "gegl-types.h"
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#include "gegl-buffer-private.h"
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#include "gegl-sampler-yafr.h"
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#include <math.h>
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#ifndef restrict
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#ifdef __restrict
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#define restrict __restrict
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#else
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#ifdef __restrict__
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#define restrict __restrict__
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#else
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#define restrict
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#endif
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#endif
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#endif
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#ifndef unlikely
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#ifdef __builtin_expect
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#define unlikely(x) __builtin_expect((x),0)
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#else
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#define unlikely(x) (x)
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#endif
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#endif
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enum
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{
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PROP_0,
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PROP_LAST
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};
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static void gegl_sampler_yafr_get ( GeglSampler *self,
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const gdouble x,
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const gdouble y,
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void *output);
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static void set_property ( GObject *gobject,
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guint property_id,
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const GValue *value,
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GParamSpec *pspec);
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static void get_property (GObject *gobject,
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guint property_id,
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GValue *value,
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GParamSpec *pspec);
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G_DEFINE_TYPE (GeglSamplerYafr, gegl_sampler_yafr, GEGL_TYPE_SAMPLER)
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/*
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* YAFR = Yet Another Fast Resampler
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*
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* Yet Another Fast Resampler is a nonlinear resampler which consists
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* of a linear scheme (in this version, Catmull-Rom) plus a nonlinear
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* sharpening correction the purpose of which is the straightening of
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* diagonal interfaces between flat colour areas.
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*
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* Key properties:
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*
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* YAFR (smooth) is interpolatory:
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*
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* If asked for the value at the center of an input pixel, it will
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* return the corresponding value, unchanged.
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*
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* YAFR (smooth) preserves local averages:
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*
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* The average of the reconstructed intensity surface over any region
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* is the same as the average of the piecewise constant surface with
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* values over pixel areas equal to the input pixel values (the
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* "nearest neighbour" surface), except for a small amount of blur at
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* the boundary of the region. More precicely: YAFR (smooth) is a box
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* filtered exact area method.
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*
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* Main weaknesses of YAFR (smooth):
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*
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* Weakness 1: YAFR (smooth) improves on Catmull-Rom only for images
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* with at least a little bit of smoothness.
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*
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* Weakness 2: Catmull-Rom introduces a lot of haloing. YAFR (smooth)
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* is based on Catmull-Rom, and consequently it too introduces a lot
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* of haloing.
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*
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* More details regarding Weakness 1:
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*
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* If a portion of the image is such that every pixel has immediate
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* neighbours in the horizontal and vertical directions which have
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* exactly the same pixel value, then YAFR (smooth) boils down to
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* Catmull-Rom, and the computation of the correction is a waste.
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* Extreme case: If all the pixels are either pure black or pure white
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* in some region, as in some text images (more generally, if the
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* region is "bichromatic"), then the YAFR (smooth) correction is 0 in
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* the interior of the bichromatic region.
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*/
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static void
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gegl_sampler_yafr_class_init (GeglSamplerYafrClass *klass)
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{
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GeglSamplerClass *sampler_class = GEGL_SAMPLER_CLASS (klass);
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GObjectClass *object_class = G_OBJECT_CLASS (klass);
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object_class->set_property = set_property;
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object_class->get_property = get_property;
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sampler_class->get = gegl_sampler_yafr_get;
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}
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static void
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gegl_sampler_yafr_init (GeglSamplerYafr *self)
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{
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/*
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* The computation stencil is 4x4, and sticks out one column to the
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* left and one row above the requested integer position:
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*/
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GEGL_SAMPLER (self)->context_rect = (GeglRectangle){-1,-1,4,4};
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GEGL_SAMPLER (self)->interpolate_format = babl_format ("RaGaBaA float");
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}
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static inline gfloat
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catrom_yafr (const gfloat cardinal_one,
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const gfloat cardinal_two,
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const gfloat cardinal_thr,
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const gfloat cardinal_fou,
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const gfloat cardinal_uno,
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const gfloat cardinal_dos,
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const gfloat cardinal_tre,
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const gfloat cardinal_qua,
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const gfloat left_width_times_up__height_times_rite_width,
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const gfloat left_width_times_dow_height_times_rite_width,
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const gfloat left_width_times_up__height_times_dow_height,
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const gfloat rite_width_times_up__height_times_dow_height,
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const gfloat* restrict this_channels_uno_one_bptr)
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{
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/*
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* "sharpening" is a continuous method parameter which is
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* proportional to the amount of "diagonal straightening" which the
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* nonlinear correction part of the method may add to the underlying
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* linear scheme. You may also think of it as a sharpening
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* parameter: higher values correspond to more sharpening, and
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* negative values lead to strange looking effects.
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*
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* The default value is sharpening = 29/32 when the scheme being
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* "straightened" is Catmull-Rom---as is the case here. This value
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* fixes key pixel values near the diagonal boundary between two
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* monochrome regions (the diagonal boundary pixel values being set
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* to the halfway colour).
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*
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* If resampling seems to add unwanted texture artifacts, push
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* sharpening toward 0. It is not generally not recommended to set
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* sharpening to a value larger than 4.
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*
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* Sharpening is halved because the .5 which has to do with the
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* relative coordinates of the evaluation points (which has to do
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* with .5*rite_width etc) is folded into the constant to save
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* flops. Consequently, the largest recommended value of
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* sharpening_over_two is 2=4/2.
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*
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* In order to simplify interfacing with users, the parameter which
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* should be set by the user is normalized so that user_sharpening =
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* 1 when sharpening is equal to the recommended value. Consistently
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* with the above discussion, values of user_sharpening between 0
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* and about 3.625 give good results.
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*/
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const gfloat user_sharpening = 1.f;
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const gfloat sharpening_over_two = user_sharpening * 0.453125f;
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/*
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* The input pixel values are described by the following stencil.
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* Spanish abbreviations are used to label positions from top to
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* bottom, English ones to label positions from left to right,:
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*
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* (ix-1,iy-1) (ix,iy-1) (ix+1,iy-1) (ix+2,iy-1)
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* =uno_one =uno_two =uno_thr = uno_fou
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*
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* (ix-1,iy) (ix,iy) (ix+1,iy) (ix+2,iy)
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* =dos_one =dos_two =dos_thr = dos_fou
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*
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* (ix-1,iy+1) (ix,iy+1) (ix+1,iy+1) (ix+2,iy+1)
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* =tre_one =tre_two =tre_thr = tre_fou
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*
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* (ix-1,iy+2) (ix,iy+2) (ix+1,iy+2) (ix+2,iy+2)
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* =qua_one =qua_two =qua_thr = qua_fou
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*/
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/*
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* Load the useful pixel values for the channel under
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* consideration. The this_channels_uno_one_bptr pointer is assumed
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* to point to uno_one when catrom_yafr is entered.
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*/
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const gint channels = 4;
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const gint pixels_per_buffer_row = 64;
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const gfloat uno_one =
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this_channels_uno_one_bptr[ 0 ];
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const gfloat uno_two =
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this_channels_uno_one_bptr[ channels ];
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const gfloat uno_thr =
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this_channels_uno_one_bptr[ 2 * channels ];
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const gfloat uno_fou =
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this_channels_uno_one_bptr[ 3 * channels ];
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const gfloat dos_one =
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this_channels_uno_one_bptr[ pixels_per_buffer_row * channels ];
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const gfloat dos_two =
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this_channels_uno_one_bptr[ ( 1 + pixels_per_buffer_row ) * channels ];
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const gfloat dos_thr =
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this_channels_uno_one_bptr[ ( 2 + pixels_per_buffer_row ) * channels ];
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const gfloat dos_fou =
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this_channels_uno_one_bptr[ ( 3 + pixels_per_buffer_row ) * channels ];
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const gfloat tre_one =
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this_channels_uno_one_bptr[ 2 * pixels_per_buffer_row * channels ];
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const gfloat tre_two =
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this_channels_uno_one_bptr[ ( 1 + 2 * pixels_per_buffer_row ) * channels ];
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const gfloat tre_thr =
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this_channels_uno_one_bptr[ ( 2 + 2 * pixels_per_buffer_row ) * channels ];
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const gfloat tre_fou =
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this_channels_uno_one_bptr[ ( 3 + 2 * pixels_per_buffer_row ) * channels ];
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const gfloat qua_one =
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this_channels_uno_one_bptr[ 3 * pixels_per_buffer_row * channels ];
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const gfloat qua_two =
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this_channels_uno_one_bptr[ ( 1 + 3 * pixels_per_buffer_row ) * channels ];
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const gfloat qua_thr =
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this_channels_uno_one_bptr[ ( 2 + 3 * pixels_per_buffer_row ) * channels ];
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const gfloat qua_fou =
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this_channels_uno_one_bptr[ ( 3 + 3 * pixels_per_buffer_row ) * channels ];
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/*
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* Computation of the YAFR correction:
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*
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* Basically, if two consecutive pixel value differences have the
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* same sign, the smallest one (in absolute value) is taken to be
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* the corresponding slope. If they don't have the same sign, the
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* corresponding slope is set to 0.
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*
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* Four such pairs (vertical and horizontal) of slopes need to be
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* computed, one pair for each of the pixels which potentially
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* overlap the unit area centered at the interpolation point.
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*/
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/*
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* Beginning of the computation of the "up" horizontal slopes:
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*/
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const gfloat prem__up = dos_two - dos_one;
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const gfloat deux__up = dos_thr - dos_two;
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const gfloat troi__up = dos_fou - dos_thr;
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/*
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* "down" horizontal slopes:
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*/
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const gfloat prem_dow = tre_two - tre_one;
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const gfloat deux_dow = tre_thr - tre_two;
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const gfloat troi_dow = tre_fou - tre_thr;
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/*
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* "left" vertical slopes:
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*/
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const gfloat prem_left = dos_two - uno_two;
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const gfloat deux_left = tre_two - dos_two;
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const gfloat troi_left = qua_two - tre_two;
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/*
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* "right" vertical slopes:
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*/
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const gfloat prem_rite = dos_thr - uno_thr;
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const gfloat deux_rite = tre_thr - dos_thr;
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const gfloat troi_rite = qua_thr - tre_thr;
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/*
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* Back to "up":
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*/
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const gfloat prem__up_squared = prem__up * prem__up;
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const gfloat deux__up_squared = deux__up * deux__up;
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const gfloat troi__up_squared = troi__up * troi__up;
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/*
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* Back to "down":
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*/
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const gfloat prem_dow_squared = prem_dow * prem_dow;
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const gfloat deux_dow_squared = deux_dow * deux_dow;
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const gfloat troi_dow_squared = troi_dow * troi_dow;
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/*
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* Back to "left":
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*/
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const gfloat prem_left_squared = prem_left * prem_left;
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const gfloat deux_left_squared = deux_left * deux_left;
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const gfloat troi_left_squared = troi_left * troi_left;
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/*
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* Back to "right":
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*/
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const gfloat prem_rite_squared = prem_rite * prem_rite;
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const gfloat deux_rite_squared = deux_rite * deux_rite;
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const gfloat troi_rite_squared = troi_rite * troi_rite;
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/*
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* "up":
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*/
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const gfloat prem__up_times_deux__up = prem__up * deux__up;
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const gfloat deux__up_times_troi__up = deux__up * troi__up;
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/*
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* "down":
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*/
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const gfloat prem_dow_times_deux_dow = prem_dow * deux_dow;
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const gfloat deux_dow_times_troi_dow = deux_dow * troi_dow;
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/*
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* "left":
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*/
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const gfloat prem_left_times_deux_left = prem_left * deux_left;
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const gfloat deux_left_times_troi_left = deux_left * troi_left;
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/*
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* "right":
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*/
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const gfloat prem_rite_times_deux_rite = prem_rite * deux_rite;
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const gfloat deux_rite_times_troi_rite = deux_rite * troi_rite;
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/*
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* Branching parts of the computation of the YAFR correction (could
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* be unbranched using arithmetic branching and C99 math intrinsics,
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* although the compiler may be smart enough to remove the branching
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* on its own):
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*/
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/*
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* "up":
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*/
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const gfloat prem__up_vs_deux__up =
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prem__up_squared < deux__up_squared ? prem__up : deux__up;
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const gfloat deux__up_vs_troi__up =
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deux__up_squared < troi__up_squared ? deux__up : troi__up;
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/*
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* "down":
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*/
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const gfloat prem_dow_vs_deux_dow =
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prem_dow_squared < deux_dow_squared ? prem_dow : deux_dow;
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const gfloat deux_dow_vs_troi_dow =
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deux_dow_squared < troi_dow_squared ? deux_dow : troi_dow;
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/*
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* "left":
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*/
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const gfloat prem_left_vs_deux_left =
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prem_left_squared < deux_left_squared ? prem_left : deux_left;
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const gfloat deux_left_vs_troi_left =
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deux_left_squared < troi_left_squared ? deux_left : troi_left;
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/*
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* "right":
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*/
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const gfloat prem_rite_vs_deux_rite =
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prem_rite_squared < deux_rite_squared ? prem_rite : deux_rite;
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const gfloat deux_rite_vs_troi_rite =
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deux_rite_squared < troi_rite_squared ? deux_rite : troi_rite;
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/*
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* The YAFR correction computation will resume after the computation
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* of the Catmull-Rom baseline.
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*/
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/*
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* Catmull-Rom baseline contribution:
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*/
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const gfloat catmull_rom =
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cardinal_uno *
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(
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cardinal_one * uno_one
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+
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cardinal_two * uno_two
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+
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cardinal_thr * uno_thr
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+
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cardinal_fou * uno_fou
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)
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+
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cardinal_dos *
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(
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cardinal_one * dos_one
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+
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cardinal_two * dos_two
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+
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cardinal_thr * dos_thr
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+
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cardinal_fou * dos_fou
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)
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+
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cardinal_tre *
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(
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cardinal_one * tre_one
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+
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cardinal_two * tre_two
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+
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cardinal_thr * tre_thr
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+
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cardinal_fou * tre_fou
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)
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+
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cardinal_qua *
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(
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cardinal_one * qua_one
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+
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cardinal_two * qua_two
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+
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cardinal_thr * qua_thr
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+
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cardinal_fou * qua_fou
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);
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/*
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* Computation of the YAFR slopes.
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*/
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/*
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* "up":
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*/
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const gfloat mx_left__up =
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prem__up_times_deux__up < 0.f ? 0.f : prem__up_vs_deux__up;
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const gfloat mx_rite__up =
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deux__up_times_troi__up < 0.f ? 0.f : deux__up_vs_troi__up;
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/*
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* "down":
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*/
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const gfloat mx_left_dow =
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prem_dow_times_deux_dow < 0.f ? 0.f : prem_dow_vs_deux_dow;
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const gfloat mx_rite_dow =
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deux_dow_times_troi_dow < 0.f ? 0.f : deux_dow_vs_troi_dow;
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/*
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* "left":
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*/
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const gfloat my_left__up =
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prem_left_times_deux_left < 0.f ? 0.f : prem_left_vs_deux_left;
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const gfloat my_left_dow =
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deux_left_times_troi_left < 0.f ? 0.f : deux_left_vs_troi_left;
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/*
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* "down":
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*/
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const gfloat my_rite__up =
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prem_rite_times_deux_rite < 0.f ? 0.f : prem_rite_vs_deux_rite;
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const gfloat my_rite_dow =
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deux_rite_times_troi_rite < 0.f ? 0.f : deux_rite_vs_troi_rite;
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/*
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* Assemble the unweighted YAFR correction:
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*/
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const gfloat unweighted_yafr_correction =
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left_width_times_up__height_times_rite_width
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*
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( mx_left__up - mx_rite__up )
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+
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left_width_times_dow_height_times_rite_width
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*
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( mx_left_dow - mx_rite_dow )
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+
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left_width_times_up__height_times_dow_height
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*
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( my_left__up - my_left_dow )
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+
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rite_width_times_up__height_times_dow_height
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*
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( my_rite__up - my_rite_dow );
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/*
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* Add the Catmull-Rom baseline and the weighted YAFR correction:
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*/
|
|
const gfloat newval =
|
|
sharpening_over_two * unweighted_yafr_correction + catmull_rom;
|
|
|
|
return newval;
|
|
}
|
|
|
|
static void
|
|
gegl_sampler_yafr_get ( GeglSampler *self,
|
|
const gdouble x,
|
|
const gdouble y,
|
|
void *output)
|
|
{
|
|
/*
|
|
* Note: The computation is structured to foster software
|
|
* pipelining.
|
|
*/
|
|
|
|
/*
|
|
* x is understood to increase from left to right, y, from top to
|
|
* bottom. Consequently, ix and iy are the indices of the pixel
|
|
* located at or to the left, and at or above. the sampling point.
|
|
*
|
|
* floor is used to make sure that the transition through 0 is
|
|
* smooth. If it is known that negative x and y will never be used,
|
|
* cast (which truncates) could be used instead.
|
|
*/
|
|
const gint ix = floorf (x);
|
|
const gint iy = floorf (y);
|
|
|
|
/*
|
|
* Pointer to enlarged input stencil values:
|
|
*/
|
|
const gfloat* restrict sampler_bptr = gegl_sampler_get_ptr (self, ix, iy);
|
|
|
|
/*
|
|
* Each (channel's) output pixel value is obtained by combining four
|
|
* "pieces," each piece corresponding to the set of points which are
|
|
* closest to the four pixels closest to the (x,y) position, pixel
|
|
* positions which have coordinates and labels as follows:
|
|
*
|
|
* (ix,iy) (ix+1,iy)
|
|
* =left__up =rite__up
|
|
*
|
|
* <- (x,y) is somewhere in the convex hull
|
|
*
|
|
* (ix,iy+1) (ix+1,iy+1)
|
|
* =left_dow =rite_dow
|
|
*/
|
|
/*
|
|
* rite_width is the width of the overlaps of the unit averaging box
|
|
* (which is centered at the position where an interpolated value is
|
|
* desired), with the closest unit pixel areas to the right.
|
|
*
|
|
* left_width is the width of the overlaps of the unit averaging box
|
|
* (which is centered at the position where an interpolated value is
|
|
* desired), with the closest unit pixel areas to the left.
|
|
*/
|
|
const gfloat rite_width = x - ix;
|
|
const gfloat dow_height = y - iy;
|
|
const gfloat left_width = 1.f - rite_width;
|
|
const gfloat up__height = 1.f - dow_height;
|
|
/*
|
|
* .5*rite_width is the x-coordinate of the center of the overlap of
|
|
* the averaging box with the left pixel areas, relative to the
|
|
* position of the centers of the left pixels.
|
|
*
|
|
* -.5*left_width is the x-coordinate ... right pixel areas,
|
|
* relative to ... the right pixels.
|
|
*
|
|
* .5*dow_height is the y-coordinate of the center of the overlap
|
|
* of the averaging box with the up pixel areas, relative to the
|
|
* position of the centers of the up pixels.
|
|
*
|
|
* -.5*up__height is the y-coordinate ... down pixel areas, relative
|
|
* to ... the down pixels.
|
|
*/
|
|
const gfloat left_width_times_rite_width = left_width * rite_width;
|
|
const gfloat up__height_times_dow_height = up__height * dow_height;
|
|
|
|
const gfloat cardinal_two =
|
|
left_width_times_rite_width * ( -1.5f * rite_width + 1.f )
|
|
+ left_width;
|
|
const gfloat cardinal_dos =
|
|
up__height_times_dow_height * ( -1.5f * dow_height + 1.f )
|
|
+ up__height;
|
|
|
|
const gfloat minus_half_left_width_times_rite_width =
|
|
-.5f * left_width_times_rite_width;
|
|
const gfloat minus_half_up__height_times_dow_height =
|
|
-.5f * up__height_times_dow_height;
|
|
|
|
const gfloat left_width_times_up__height_times_rite_width =
|
|
left_width_times_rite_width * up__height;
|
|
const gfloat left_width_times_dow_height_times_rite_width =
|
|
left_width_times_rite_width * dow_height;
|
|
const gfloat left_width_times_up__height_times_dow_height =
|
|
up__height_times_dow_height * left_width;
|
|
const gfloat rite_width_times_up__height_times_dow_height =
|
|
up__height_times_dow_height * rite_width;
|
|
|
|
const gfloat cardinal_one =
|
|
minus_half_left_width_times_rite_width * left_width;
|
|
const gfloat cardinal_uno =
|
|
minus_half_up__height_times_dow_height * up__height;
|
|
|
|
const gfloat cardinal_fou =
|
|
minus_half_left_width_times_rite_width * rite_width;
|
|
const gfloat cardinal_qua =
|
|
minus_half_up__height_times_dow_height * dow_height;
|
|
|
|
const gfloat cardinal_thr =
|
|
1.f - ( minus_half_left_width_times_rite_width + cardinal_two );
|
|
const gfloat cardinal_tre =
|
|
1.f - ( minus_half_up__height_times_dow_height + cardinal_dos );
|
|
|
|
/*
|
|
* The newval array will contain the four (one per channel)
|
|
* computed resampled values:
|
|
*/
|
|
gfloat newval[4];
|
|
|
|
/*
|
|
* Set the tile pointer to the first relevant value. Since the
|
|
* pointer initially points to dos_two, we need to rewind it one
|
|
* tile row, then go back one additional pixel.
|
|
*/
|
|
const gint channels = 4;
|
|
const gint pixels_per_buffer_row = 64;
|
|
sampler_bptr -= ( pixels_per_buffer_row + 1 ) * channels;
|
|
|
|
newval[0] = catrom_yafr (cardinal_one,
|
|
cardinal_two,
|
|
cardinal_thr,
|
|
cardinal_fou,
|
|
cardinal_uno,
|
|
cardinal_dos,
|
|
cardinal_tre,
|
|
cardinal_qua,
|
|
left_width_times_up__height_times_rite_width,
|
|
left_width_times_dow_height_times_rite_width,
|
|
left_width_times_up__height_times_dow_height,
|
|
rite_width_times_up__height_times_dow_height,
|
|
sampler_bptr++);
|
|
newval[1] = catrom_yafr (cardinal_one,
|
|
cardinal_two,
|
|
cardinal_thr,
|
|
cardinal_fou,
|
|
cardinal_uno,
|
|
cardinal_dos,
|
|
cardinal_tre,
|
|
cardinal_qua,
|
|
left_width_times_up__height_times_rite_width,
|
|
left_width_times_dow_height_times_rite_width,
|
|
left_width_times_up__height_times_dow_height,
|
|
rite_width_times_up__height_times_dow_height,
|
|
sampler_bptr++);
|
|
newval[2] = catrom_yafr (cardinal_one,
|
|
cardinal_two,
|
|
cardinal_thr,
|
|
cardinal_fou,
|
|
cardinal_uno,
|
|
cardinal_dos,
|
|
cardinal_tre,
|
|
cardinal_qua,
|
|
left_width_times_up__height_times_rite_width,
|
|
left_width_times_dow_height_times_rite_width,
|
|
left_width_times_up__height_times_dow_height,
|
|
rite_width_times_up__height_times_dow_height,
|
|
sampler_bptr++);
|
|
newval[3] = catrom_yafr (cardinal_one,
|
|
cardinal_two,
|
|
cardinal_thr,
|
|
cardinal_fou,
|
|
cardinal_uno,
|
|
cardinal_dos,
|
|
cardinal_tre,
|
|
cardinal_qua,
|
|
left_width_times_up__height_times_rite_width,
|
|
left_width_times_dow_height_times_rite_width,
|
|
left_width_times_up__height_times_dow_height,
|
|
rite_width_times_up__height_times_dow_height,
|
|
sampler_bptr);
|
|
|
|
/*
|
|
* Ship out newval:
|
|
*/
|
|
babl_process (babl_fish (self->interpolate_format, self->format),
|
|
newval,
|
|
output,
|
|
1);
|
|
}
|
|
|
|
static void
|
|
set_property ( GObject *gobject,
|
|
guint property_id,
|
|
const GValue *value,
|
|
GParamSpec *pspec)
|
|
{
|
|
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, property_id, pspec);
|
|
}
|
|
|
|
static void
|
|
get_property (GObject *gobject,
|
|
guint property_id,
|
|
GValue *value,
|
|
GParamSpec *pspec)
|
|
{
|
|
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, property_id, pspec);
|
|
}
|