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added nohalo.c

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John Cupitt 2009-01-20 21:32:05 +00:00
parent 20314dd166
commit defdf1655b
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/* nohalo 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
*/
/*
* 2009 (c) Nicolas Robidoux
*
* Thanks: Geert Jordaens, John Cupitt, Minglun Gong, Øyvind Kolås and
* Sven Neumann for useful comments and code.
*
* Acknowledgement: Nicolas Robidoux's research on nohalo funded in
* part by an NSERC (National Science and Engineering Research Council
* of Canada) Discovery Grant.
*/
/* Hacked for vips by J. Cupitt, 20/1/09
*/
/*
* John: This is the version which I think you should base the code
* for signed and unsigned ints, floats and doubles. IN_AND_OUT_TYPE
* stands for the "input" and "output" types. The computation is
* performed based on doubles (even for float data). There is a reason
* for this, which is that I use implicit casts of flag variables into
* ints into doubles, and I think that such casts may be slower from
* ints to floats.
*
* IMPORTANT: Because nohalo is monotone, there is no need to clamp,
* ever.
*
* I have inserted code which I hope does fairly quick rounding to
* nearest when signed or unsigned ints are used. Look for the word
* "John".
*
* Set the LGPL license to what you like. As long as my name is
* suitably inserted, I don't care about the exact license.
*/
/*
* This is not "REAL" gegl code, because I don't like the way
* gegl_sampler_get_ptr works (when I use it as I like, there are
* glitches in gegl which I think have nothing to do with my code). I
* rewrote the following code the way I'd like get_ptr to work.
*/
/*
* ================
* NOHALO RESAMPLER
* ================
*
* "Nohalo" is a family of parameterized resamplers with a mission:
* smoothly straightening oblique lines without undesirable
* side-effects.
*
* The key parameter, which may be described as a "quality" parameter,
* is an integer which specifies the number of "levels" of binary
* subdivision which are performed. If level = 0 can be thought of as
* being plain vanilla bilinear resampling; level = 1 is the first
* "non-classical" method.
*
* Besides increasing computational cost, increasing the number of
* levels increases the quality of the resampled pixel value unless
* the resampled location happens to be exactly where a subdivided
* grid point (for this level) is located, in which case further
* levels do not change the answer, and consequently do not increase
* its quality.
*
* ============================================================
* WARNING: THIS CODE ONLY IMPLEMENTS THE LOWEST QUALITY NOHALO
* ============================================================
*
* This code implement nohalo for (quality) level = 1. Nohalo for
* higher quality levels will be implemented later.
*
* Key properties:
*
* =======================
* Nohalo is interpolatory
* =======================
*
* That is, nohalo preserves point values: If asked for the value at
* the center of an input pixel, the sampler returns the corresponding
* value, unchanged. In addition, because nohalo is continuous, if
* asked for a value at a location "very close" to the center of an
* input pixel, then the sampler returns a value "very close" to
* it. (Nohalo is not smoothing like, say, B-Spline
* pseudo-interpolation.)
*
* ========================================================
* Nohalo is co-monotone (this is why it's called "nohalo")
* ========================================================
*
* What monotonicity means here is that the resampled value is in the
* range of the four closest input values. Consequently, nohalo does
* not add haloing. It also means that clamping is unnecessary
* (provided abyss values are within the range of acceptable values,
* which is always the case). (Note: plain vanilla bilinear is also
* co-monotone.)
*
* Note: If the abyss policy is an extrapolating one---for example,
* linear or bilinear extrapolation---clamping is still unnecessary
* unless one attempts to resample outside of the convex hull of the
* input pixel positions. Consequence: the "corner" image size
* convention does not require clamping when using linear
* extrapolation abyss policy when performing image resizing, but the
* "center" one does, when upscaling, at locations very close to the
* boundary. If computing values at locations outside of the convex
* hull of the pixel locations of the input image, nearest neighbour
* abyss policy is most likely better anyway, because linear
* extrapolation produces "streaks" if positions far outside the
* original image boundary are resampled.
*
* ========================
* Nohalo is a local method
* ========================
*
* The value of the reconstructed intensity surface at any point
* depends on the values of (at most) 12 nearby input values, located
* in a "cross" centered at the closest four input pixel centers. For
* computational expediency, the input values corresponding to the
* nearest 21 input pixel locations (5x5 minus the four corners)
* should be made available through a data pointer. The code then
* selects the needed ones from this enlarged stencil.
*
* ===========================================================
* When level = infinity, nohalo's intensity surface is smooth
* ===========================================================
*
* It is conjectured that the intensity surface is infinitely
* differentiable. Consequently, "Mach banding" (primarily caused by
* sharp "ridges" in the reconstructed intensity surface and
* particularly noticeable, for example, when using bilinear
* resampling) is (essentially) absent, even at high magnifications,
* WHEN THE LEVEL IS HIGH (more or less when 2^(level+1) is at least
* the largest local magnification factor, which means that the level
* 1 nohalo does not show much Mach banding up to a magnification of
* about 4).
*
* ===============================
* Nohalo is second order accurate
* ===============================
*
* (Except possibly near the boundary: it is easy to make this
* property carry over everywhere but this requires a tuned abyss
* policy or building the boundary conditions inside the sampler.)
* Nohalo is exact on linear intensity profiles, meaning that if the
* input pixel values (in the stencil) are obtained from a function of
* the form f(x,y) = a + b*x + c*y (a, b, c constants), then the
* computed pixel value is exactly the value of f(x,y) at the
* asked-for sampling location.
*
* ===================
* Nohalo is nonlinear
* ===================
*
* In particular, resampling a sum of images may not be the same as
* summing the resamples (this occurs even without taking into account
* over and underflow issues: images can only take values within a
* banded range, and consequently no sampler is truly linear.)
*
* ====================
* Weaknesses of nohalo
* ====================
*
* In some cases, the first level nonlinear computation is wasted:
*
* If a region is bichromatic, the nonlinear component of the level 1
* nohalo is zero in the interior of the region, and consequently
* nohalo boils down to bilinear. For such images, either stick to
* bilinear, or use a higher level (quality) setting. (There is no
* real harm in using nohalo when it boils down to bilinear if one
* does not mind wasting cycles.)
*
* Low quality levels do NOT produce a continuously differentiable
* intensity surface:
*
* With a "finite" level is used (that is, in practice), the nohalo
* intensity surface is only continuous: there are gradient
* discontinuities because the "final interpolation step" is performed
* with bilinear. (Exception: if the "corner" image size convention is
* used and the magnification factor is 2, that is, if the resampled
* points sit exactly on the binary subdivided grid, then nohalo level
* 1 gives the same result as as level=infinity, and consequently the
* intensity surface can be treated as if smooth.)
*/
/*
#define DEBUG
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <stdlib.h>
#include <vips/vips.h>
#include <vips/internal.h>
#include "templates.h"
#ifndef restrict
#ifdef __restrict
#define restrict __restrict
#else
#ifdef __restrict__
#define restrict __restrict__
#else
#define restrict
#endif
#endif
#endif
/*
* FAST_PSEUDO_FLOOR is a floor and floorf replacement which has been
* found to be faster on several linux boxes than the library
* version. It returns the floor of its argument unless the argument
* is a negative integer, in which case it returns one less than the
* floor. For example:
*
* FAST_PSEUDO_FLOOR(0.5) = 0
*
* FAST_PSEUDO_FLOOR(0.f) = 0
*
* FAST_PSEUDO_FLOOR(-.5) = -1
*
* as expected, but
*
* FAST_PSEUDO_FLOOR(-1.f) = -2
*
* The locations of the discontinuities of FAST_PSEUDO_FLOOR are the
* same as floor and floorf; it is just that at negative integers the
* function is discontinuous on the right instead of the left.
*/
#define FAST_PSEUDO_FLOOR(x) ( (int)(x) - ( (x) < 0. ) )
/*
* Alternative (if conditional move is fast and correctly identified
* by the compiler):
*
* #define FAST_PSEUDO_FLOOR(x) ( (x)>=0 ? (int)(x) : (int)(x)-1 )
*/
enum
{
PROP_0,
PROP_LAST
};
static void gegl_sampler_yafr_get ( GeglSampler* restrict self,
const gdouble absolute_x,
const gdouble absolute_y,
void* restrict output);
static void set_property (GObject* gobject,
guint property_id,
GValue* value,
GParamSpec* pspec);
static void get_property (GObject* gobject,
guint property_id,
GValue* value,
GParamSpec* pspec);
G_DEFINE_TYPE( GeglSamplerYafr, gegl_sampler_yafr, GEGL_TYPE_SAMPLER )
static void
gegl_sampler_yafr_class_init (GeglSamplerYafrClass *klass)
{
GeglSamplerClass *sampler_class = GEGL_SAMPLER_CLASS (klass);
GObjectClass *object_class = G_OBJECT_CLASS (klass);
object_class->set_property = set_property;
object_class->get_property = get_property;
sampler_class->get = gegl_sampler_yafr_get;
}
static void
gegl_sampler_yafr_init (GeglSamplerYafr *self)
{
/*
* context_rect is a five-by-five stencil centered around the
* nearest input pixel center. See comment below about using a
* "non-centered" stencil (one based at the corner) instead.
*/
GEGL_SAMPLER (self)->context_rect = (GeglRectangle){0,0,5,5};
GEGL_SAMPLER (self)->interpolate_format = babl_format ("RaGaBaA float");
}
static inline IN_AND_OUT_TYPE
nohalo1 (const gdouble w_times_z,
const gdouble x_times_z,
const gdouble w_times_y,
const gdouble x_times_y,
const gdouble dos_thr,
const gdouble dos_fou,
const gdouble tre_two,
const gdouble tre_thr,
const gdouble tre_fou,
const gdouble tre_fiv,
const gdouble qua_two,
const gdouble qua_thr,
const gdouble qua_fou,
const gdouble qua_fiv,
const gdouble cin_thr,
const gdouble cin_fou)
{
/*
* The potentially needed input pixel values are described by the
* following stencil, where (ix,iy) are the coordinates of the
* closest input pixel center (with ties resolved arbitrarily).
*
* Spanish abbreviations are used to label positions from top to
* bottom (rows), English ones to label positions from left to right
* (columns).
*
* (ix-1,iy-2) (ix,iy-2) (ix+1,iy-2)
* = uno_two = uno_thr = uno_fou
*
* (ix-2,iy-1) (ix-1,iy-1) (ix,iy-1) (ix+1,iy-1) (ix+2,iy-1)
* = dos_one = dos_two = dos_thr = dos_fou = dos_fiv
*
* (ix-2,iy) (ix-1,iy) (ix,iy) (ix+1,iy) (ix+2,iy)
* = tre_one = tre_two = tre_thr = tre_fou = tre_fiv
*
* (ix-2,iy+1) (ix-1,iy+1) (ix,iy+1) (ix+1,iy+1) (ix+2,iy+1)
* = qua_one = qua_two = qua_thr = qua_fou = qua_fiv
*
* (ix-1,iy+2) (ix,iy+2) (ix+1,iy+2)
* = cin_two = cin_thr = cin_fou
*
* Once symmetry has been used to assume that the sampling point is
* to the right and bottom of tre_thr---this is done by implicitly
* reflecting the data if this is not initially the case---the
* needed input values are named thus:
*
* dos_thr dos_fou
*
* tre_two tre_thr tre_fou tre_fiv
*
* qua_two qua_thr qua_fou qua_fiv
*
* cin_thr cin_fou
*
* (If, for exammple, relative_x_is_left is 1 but relative_y_is___up
* = 0, then dos_fou in this post-reflexion reduced stencil really
* corresponds to dos_two in the unreduced one, etc.)
*
* Given that the reflexions are performed "outside of the
* function," the above 12 input values are the only ones "seen" by
* this function.
*/
/*
* Computation of the nonlinear slopes: If two consecutive pixel
* value differences have the same sign, the smallest one (in
* absolute value) is taken to be the corresponding slope; if the
* two consecutive pixel value differences don't have the same sign,
* the corresponding slope is set to 0.
*/
/*
* Tre(s) horizontal differences:
*/
const gdouble deux_tre = tre_thr - tre_two;
const gdouble troi_tre = tre_fou - tre_thr;
const gdouble quat_tre = tre_fiv - tre_fou;
/*
* Qua(ttro) horizontal differences:
*/
const gdouble deux_qua = qua_thr - qua_two;
const gdouble troi_qua = qua_fou - qua_thr;
const gdouble quat_qua = qua_fiv - qua_fou;
/*
* Thr(ee) vertical differences:
*/
const gdouble deux_thr = tre_thr - dos_thr;
const gdouble troi_thr = qua_thr - tre_thr;
const gdouble quat_thr = cin_thr - qua_thr;
/*
* Fou(r) vertical differences:
*/
const gdouble deux_fou = tre_fou - dos_fou;
const gdouble troi_fou = qua_fou - tre_fou;
const gdouble quat_fou = cin_fou - qua_fou;
/*
* Tre:
*/
const gint sign_deux_tre = 2 * ( deux_tre >= 0. ) - 1;
const gint sign_troi_tre = 2 * ( troi_tre >= 0. ) - 1;
const gint sign_quat_tre = 2 * ( quat_tre >= 0. ) - 1;
/*
* Qua:
*/
const gint sign_deux_qua = 2 * ( deux_qua >= 0. ) - 1;
const gint sign_troi_qua = 2 * ( troi_qua >= 0. ) - 1;
const gint sign_quat_qua = 2 * ( quat_qua >= 0. ) - 1;
/*
* Thr:
*/
const gint sign_deux_thr = 2 * ( deux_thr >= 0. ) - 1;
const gint sign_troi_thr = 2 * ( troi_thr >= 0. ) - 1;
const gint sign_quat_thr = 2 * ( quat_thr >= 0. ) - 1;
/*
* Fou:
*/
const gint sign_deux_fou = 2 * ( deux_fou >= 0. ) - 1;
const gint sign_troi_fou = 2 * ( troi_fou >= 0. ) - 1;
const gint sign_quat_fou = 2 * ( quat_fou >= 0. ) - 1;
/*
* Tre:
*/
const gdouble abs_deux_tre = sign_deux_tre * deux_tre;
const gdouble abs_troi_tre = sign_troi_tre * troi_tre;
const gdouble abs_quat_tre = sign_quat_tre * quat_tre;
/*
* Qua:
*/
const gdouble abs_deux_qua = sign_deux_qua * deux_qua;
const gdouble abs_troi_qua = sign_troi_qua * troi_qua;
const gdouble abs_quat_qua = sign_quat_qua * quat_qua;
/*
* Thr:
*/
const gdouble abs_deux_thr = sign_deux_thr * deux_thr;
const gdouble abs_troi_thr = sign_troi_thr * troi_thr;
const gdouble abs_quat_thr = sign_quat_thr * quat_thr;
/*
* Fou:
*/
const gdouble abs_deux_fou = sign_deux_fou * deux_fou;
const gdouble abs_troi_fou = sign_troi_fou * troi_fou;
const gdouble abs_quat_fou = sign_quat_fou * quat_fou;
/*
* Tre:
*/
const gdouble twice_tre_thr_horizo =
( 1 + sign_deux_tre * sign_troi_tre )
*
(
( abs_deux_tre <= abs_troi_tre )
*
( deux_tre - troi_tre )
+
troi_tre
);
const gdouble twice_tre_fou_horizo =
( 1 + sign_troi_tre * sign_quat_tre )
*
(
( abs_troi_tre <= abs_quat_tre )
*
( troi_tre - quat_tre )
+
quat_tre
);
/*
* Qua:
*/
const gdouble twice_qua_thr_horizo =
( 1 + sign_deux_qua * sign_troi_qua )
*
(
( abs_deux_qua <= abs_troi_qua )
*
( deux_qua - troi_qua )
+
troi_qua
);
const gdouble twice_qua_fou_horizo =
( 1 + sign_troi_qua * sign_quat_qua )
*
(
( abs_troi_qua <= abs_quat_qua )
*
( troi_qua - quat_qua )
+
quat_qua
);
/*
* Thr:
*/
const gdouble twice_tre_thr_vertic =
( 1 + sign_deux_thr * sign_troi_thr )
*
(
( abs_deux_thr <= abs_troi_thr )
*
( deux_thr - troi_thr )
+
troi_thr
);
const gdouble twice_qua_thr_vertic =
( 1 + sign_troi_thr * sign_quat_thr )
*
(
( abs_troi_thr <= abs_quat_thr )
*
( troi_thr - quat_thr )
+
quat_thr
);
/*
* Fou:
*/
const gdouble twice_tre_fou_vertic =
( 1 + sign_deux_fou * sign_troi_fou )
*
(
( abs_deux_fou <= abs_troi_fou )
*
( deux_fou - troi_fou )
+
troi_fou
);
const gdouble twice_qua_fou_vertic =
( 1 + sign_troi_fou * sign_quat_fou )
*
(
( abs_troi_fou <= abs_quat_fou )
*
( troi_fou - quat_fou )
+
quat_fou
);
/*
* Compute the needed "horizontal" (at the boundary between two
* input pixel areas) double resolution pixel value:
*/
/*
* Tre:
*/
const gdouble tre_thrfou =
.5 * ( tre_thr + tre_fou )
+
.125 * ( twice_tre_thr_horizo - twice_tre_fou_horizo );
/*
* Compute the needed "vertical" double resolution pixel value:
*/
/*
* Thr:
*/
const gdouble trequa_thr =
.5 * ( tre_thr + qua_thr )
+
.125 * ( twice_tre_thr_vertic - twice_qua_thr_vertic );
/*
* Compute the "diagonal" (at the boundary between four input pixel
* areas) double resolution pixel value:
*/
const gdouble trequa_thrfou =
.25 * ( qua_fou - tre_thr )
+
.5 * ( tre_thrfou + trequa_thr )
+
.0625
*
(
( twice_qua_thr_horizo + twice_tre_fou_vertic )
-
( twice_qua_fou_horizo + twice_qua_fou_vertic )
);
/*
* Compute the output pixel values, doing the final interpolation
* step with bilinear:
*/
const IN_AND_OUT_TYPE newval =
w_times_z * tre_thr
+
x_times_z * tre_thrfou
+
w_times_y * trequa_thr
+
x_times_y * trequa_thrfou;
/*
* The above works if with gfloats and gdoubles. However, in order
* to get correct rounding when one uses "full" integers, use the
* following two versions:
*/
/*
* If the IN_AND_OUT_TYPE is unsigned integer, use this:
*/
const IN_AND_OUT_TYPE newval =
.5
+
w_times_z_over_sixteen * tre_thr
+
x_times_z_over_sixteen * tre_thrfou
+
w_times_y_over_sixteen * trequa_thr
+
x_times_y_over_sixteen * trequa_thrfou;
/*
* If the IN_AND_OUT_TYPE is signed integer, use this:
*/
const gdouble val =
w_times_z_over_sixteen * tre_thr
+
x_times_z_over_sixteen * tre_thrfou
+
w_times_y_over_sixteen * trequa_thr
+
x_times_y_over_sixteen * trequa_thrfou;
const int sign_of_val = 2 * ( val >= 0. ) - 1;
const int rounded_abs_val = .5 + sign_of_val * val;
const IN_AND_OUT_TYPE newval = sign_of_val * rounded_abs_val;
return newval;
}
static void
gegl_sampler_yafr_get ( GeglSampler* restrict self,
const gdouble absolute_x,
const gdouble absolute_y,
void* restrict output)
{
/*
* NEEDED CONSTANTS RELATED TO THE INPUT PIXEL POINTER:
*/
const gint channels_per_pixel = 4;
const gint pixels_per_tile_row = 64;
const gint values_per_tile_row = channels_per_pixel * pixels_per_tile_row;
/*
* floor's surrogate FAST_PSEUDO_FLOOR is used to make sure that the
* transition through 0 is smooth. If it is known that absolute_x
* and absolute_y will never be less than -.5, plain cast---that is,
* const gint ix = absolute_x + .5---should be used instead. Any
* function which agrees with floor for non-integer values, and
* picks one of the two possibilities for integer values, can be
* used.
*/
const gint ix = FAST_PSEUDO_FLOOR (absolute_x + .5);
const gint iy = FAST_PSEUDO_FLOOR (absolute_y + .5);
/*
* x is the x-coordinate of the sampling point relative to the
* position of the tre_thr pixel center. Similarly for y. Range of
* values: [-.5,.5].
*/
const gdouble relative_x = absolute_x - ix;
const gdouble relative_y = absolute_y - iy;
/*
* "DIRTY" TRICK: In order to minimize the number of computed
* "double density" pixels, we use symmetry to appropriately "flip
* the data." (An alternative approach is to "compute everything and
* select by zeroing coefficients.")
*/
const gint relative_x_is_left = ( relative_x < 0. );
const gint relative_y_is___up = ( relative_y < 0. );
const gint basic_x_reflexion_shift = ( 5 - 1 ) * channels_per_pixel;
const gint basic_y_reflexion_shift = ( 5 - 1 ) * values_per_tile_row;
const gint x_reflexion_shift = basic_x_reflexion_shift * relative_x_is_left;
const gint y_reflexion_shift = basic_y_reflexion_shift * relative_y_is___up;
/*
* gegl_sampler_get_ptr (self, ix-2, iy-2) should give me access to
* a 5 by 5 black of pixel data, where the leftmost/topmost pixel is
* located at (ix-2,iy-2)---that is, the data runs from "absolute
* indices" ix-2 to ix+2 and iy-2 to iy+2. Note that the four
* corners of this 5x5 block are never used.
*
* Adding x_reflexion_shift and y_reflexion_shift to the input data
* pointer, otherwise pointing to the (first channel of the) top
* left of the five by five stencil, will bring it to the desired
* corner:
*/
const IN_AND_OUT_TYPE* restrict uno_one_input_bptr =
gegl_sampler_get_ptr (self, ix-2, iy-2)
+
(
x_reflexion_shift
+
y_reflexion_shift
);
/*
* The direction of movement within the (extended) possibly
* reflected stencil is then determined by the following signs:
*/
const gint sign_of_relative_x = 1 - 2 * relative_x_is_left;
const gint sign_of_relative_y = 1 - 2 * relative_y_is___up;
/*
* Unit shifts:
*/
const gint shift_1_pixel = sign_of_relative_x * channels_per_pixel;
const gint shift_1_row = sign_of_relative_y * values_per_tile_row;
/*
* POST REFLEXION/POST RESCALING "DOUBLE DENSITY" COORDINATES:
*
* With the appropriate reflexions, we can assume that the
* coordinates are positive (that we are in the bottom right
* quadrant (in quadrant III) relative to tre_thr). It is also
* convenient to scale things by 2, so that the "double density
* pixels" are 1---instead of 1/2---apart:
*/
const gdouble x = ( 2 * sign_of_relative_x ) * relative_x;
const gdouble y = ( 2 * sign_of_relative_y ) * relative_y;
/*
* Basic shifts:
*/
const gint shift_2_pixels = 2 * shift_1_pixel;
const gint shift_2_rows = 2 * shift_1_row;
/*
* FIRST BILINEAR WEIGHT:
*/
const gdouble x_times_y = x * y;
/*
* More basic shifts:
*/
const gint shift_3_pixels = shift_2_pixels + shift_1_pixel;
const gint shift_3_rows = shift_2_rows + shift_1_row;
const gint shift_4_rows = 2 * shift_2_rows;
const gint shift_4_pixels = 2 * shift_2_pixels;
/*
* SECOND AND THIRD BILINEAR WEIGHTS:
*
* (Note: w = 1-x and z = 1-y.)
*/
const gdouble w_times_y = y - x_times_y;
const gdouble x_times_z = x - x_times_y;
/*
* OVERALL SHIFTS:
*/
const gint dos_thr_shift = shift_1_row + shift_2_pixels;
const gint dos_fou_shift = shift_1_row + shift_3_pixels;
const gint tre_two_shift = shift_2_rows + shift_1_pixel;
const gint tre_thr_shift = shift_2_rows + shift_2_pixels;
const gint tre_fou_shift = shift_2_rows + shift_3_pixels;
const gint tre_fiv_shift = shift_2_rows + shift_4_pixels;
const gint qua_two_shift = shift_3_rows + shift_1_pixel;
const gint qua_thr_shift = shift_3_rows + shift_2_pixels;
const gint qua_fou_shift = shift_3_rows + shift_3_pixels;
const gint qua_fiv_shift = shift_3_rows + shift_4_pixels;
const gint cin_thr_shift = shift_4_rows + shift_2_pixels;
const gint cin_fou_shift = shift_4_rows + shift_3_pixels;
/*
* LAST BILINEAR WEIGHT:
*/
const gdouble w_times_z = 1. - ( x + w_times_y );
/*
* The newval array will contain the four (one per channel)
* computed resampled values:
*/
IN_AND_OUT_TYPE newval[4];
/*
* COMPUTATION OF EACH CHANNEL'S RESAMPLED PIXEL VALUE:
*/
/*
* First channel:
*/
newval[0] = nohalo1 (w_times_z,
x_times_z,
w_times_y,
x_times_y,
uno_one_input_bptr[ dos_thr_shift ],
uno_one_input_bptr[ dos_fou_shift ],
uno_one_input_bptr[ tre_two_shift ],
uno_one_input_bptr[ tre_thr_shift ],
uno_one_input_bptr[ tre_fou_shift ],
uno_one_input_bptr[ tre_fiv_shift ],
uno_one_input_bptr[ qua_two_shift ],
uno_one_input_bptr[ qua_thr_shift ],
uno_one_input_bptr[ qua_fou_shift ],
uno_one_input_bptr[ qua_fiv_shift ],
uno_one_input_bptr[ cin_thr_shift ],
uno_one_input_bptr[ cin_fou_shift ]);
/*
* Shift input pointer by one channel:
*/
uno_one_input_bptr++;
/*
* Second channel:
*/
newval[1] = nohalo1 (w_times_z,
x_times_z,
w_times_y,
x_times_y,
uno_one_input_bptr[ dos_thr_shift ],
uno_one_input_bptr[ dos_fou_shift ],
uno_one_input_bptr[ tre_two_shift ],
uno_one_input_bptr[ tre_thr_shift ],
uno_one_input_bptr[ tre_fou_shift ],
uno_one_input_bptr[ tre_fiv_shift ],
uno_one_input_bptr[ qua_two_shift ],
uno_one_input_bptr[ qua_thr_shift ],
uno_one_input_bptr[ qua_fou_shift ],
uno_one_input_bptr[ qua_fiv_shift ],
uno_one_input_bptr[ cin_thr_shift ],
uno_one_input_bptr[ cin_fou_shift ]);
uno_one_input_bptr++;
newval[2] = nohalo1 (w_times_z,
x_times_z,
w_times_y,
x_times_y,
uno_one_input_bptr[ dos_thr_shift ],
uno_one_input_bptr[ dos_fou_shift ],
uno_one_input_bptr[ tre_two_shift ],
uno_one_input_bptr[ tre_thr_shift ],
uno_one_input_bptr[ tre_fou_shift ],
uno_one_input_bptr[ tre_fiv_shift ],
uno_one_input_bptr[ qua_two_shift ],
uno_one_input_bptr[ qua_thr_shift ],
uno_one_input_bptr[ qua_fou_shift ],
uno_one_input_bptr[ qua_fiv_shift ],
uno_one_input_bptr[ cin_thr_shift ],
uno_one_input_bptr[ cin_fou_shift ]);
uno_one_input_bptr++;
newval[3] = nohalo1 (w_times_z,
x_times_z,
w_times_y,
x_times_y,
uno_one_input_bptr[ dos_thr_shift ],
uno_one_input_bptr[ dos_fou_shift ],
uno_one_input_bptr[ tre_two_shift ],
uno_one_input_bptr[ tre_thr_shift ],
uno_one_input_bptr[ tre_fou_shift ],
uno_one_input_bptr[ tre_fiv_shift ],
uno_one_input_bptr[ qua_two_shift ],
uno_one_input_bptr[ qua_thr_shift ],
uno_one_input_bptr[ qua_fou_shift ],
uno_one_input_bptr[ qua_fiv_shift ],
uno_one_input_bptr[ cin_thr_shift ],
uno_one_input_bptr[ cin_fou_shift ]);
/*
* Ship out the newval (computed new pixel values):
*/
babl_process (babl_fish (self->interpolate_format, self->format),
newval,
output,
1);
}
static void
set_property (GObject* gobject,
guint property_id,
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);
}