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libvips/libvips/create/tonelut.c

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/* Build a tone curve.
*
* Author: John Cupitt
* Written on: 18/7/1995
* 17/9/96 JC
* - restrictions on Ps, Pm, Ph relaxed
* - restrictions on S, M, H relaxed
* 25/7/01 JC
* - patched for im_extract_band() change
* 11/7/04
* - generalised to im_tone_build_range() ... so you can use it for any
* image, not just LabS
* 26/3/10
* - cleanups
* - gtkdoc
* 20/9/13
* - redo as a class
*/
/*
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., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <vips/vips.h>
#include "pcreate.h"
typedef struct _VipsTonelut {
VipsCreate parent_instance;
/* Parameters for tone curve formation.
*/
double Lb, Lw;
double Ps, Pm, Ph;
double S, M, H;
/* Range we process.
*/
int in_max;
int out_max;
/* Derived values.
*/
double Ls, Lm, Lh;
} VipsTonelut;
typedef VipsCreateClass VipsTonelutClass;
G_DEFINE_TYPE( VipsTonelut, vips_tonelut, VIPS_TYPE_CREATE );
/* Calculate shadow curve.
*/
static double
shad( VipsTonelut *lut, double x )
{
double x1 = (x - lut->Lb) / (lut->Ls - lut->Lb);
double x2 = (x - lut->Ls) / (lut->Lm - lut->Ls);
double out;
if( x < lut->Lb )
out = 0;
else if( x < lut->Ls )
out = 3.0 * x1 * x1 - 2.0 * x1 * x1 * x1;
else if( x < lut->Lm )
out = 1.0 - 3.0 * x2 * x2 + 2.0 * x2 * x2 * x2;
else
out = 0;
return( out );
}
/* Calculate mid-tone curve.
*/
static double
mid( VipsTonelut *lut, double x )
{
double x1 = (x - lut->Ls) / (lut->Lm - lut->Ls);
double x2 = (x - lut->Lm) / (lut->Lh - lut->Lm);
double out;
if( x < lut->Ls )
out = 0;
else if( x < lut->Lm )
out = 3.0 * x1 * x1 - 2.0 * x1 * x1 * x1;
else if( x < lut->Lh )
out = 1.0 - 3.0 * x2 * x2 + 2.0 * x2 * x2 * x2;
else
out = 0;
return( out );
}
/* Calculate highlight curve.
*/
static double
high( VipsTonelut *lut, double x )
{
double x1 = (x - lut->Lm) / (lut->Lh - lut->Lm);
double x2 = (x - lut->Lh) / (lut->Lw - lut->Lh);
double out;
if( x < lut->Lm )
out = 0;
else if( x < lut->Lh )
out = 3.0 * x1 * x1 - 2.0 * x1 * x1 * x1;
else if( x < lut->Lw )
out = 1.0 - 3.0 * x2 * x2 + 2.0 * x2 * x2 * x2;
else
out = 0;
return( out );
}
/* Generate a point on the tone curve. Everything is 0-100.
*/
static double
tone_curve( VipsTonelut *lut, double x )
{
double out;
out = x +
lut->S * shad( lut, x ) +
lut->M * mid( lut, x ) +
lut->H * high( lut, x );
return( out );
}
static int
vips_tonelut_build( VipsObject *object )
{
VipsCreate *create = VIPS_CREATE( object );
VipsTonelut *lut = (VipsTonelut *) object;
int i;
unsigned short buf[65536];
if( VIPS_OBJECT_CLASS( vips_tonelut_parent_class )->build( object ) )
return( -1 );
g_assert( lut->in_max > 0 && lut->in_max < 65536 );
g_assert( lut->out_max > 0 && lut->out_max < 65536 );
/* Note derived params.
*/
lut->Ls = lut->Lb + lut->Ps * (lut->Lw - lut->Lb);
lut->Lm = lut->Lb + lut->Pm * (lut->Lw - lut->Lb);
lut->Lh = lut->Lb + lut->Ph * (lut->Lw - lut->Lb);
/* Generate curve.
*/
for( i = 0; i <= lut->in_max; i++ ) {
int v = (lut->out_max / 100.0) *
tone_curve( lut, 100.0 * i / lut->in_max );
if( v < 0 )
v = 0;
else if( v > lut->out_max )
v = lut->out_max;
buf[i] = v;
}
/* Make the output image.
*/
vips_image_init_fields( create->out,
lut->in_max + 1, 1, 1,
VIPS_FORMAT_USHORT, VIPS_CODING_NONE,
VIPS_INTERPRETATION_HISTOGRAM, 1.0, 1.0 );
if( vips_image_write_line( create->out, 0, (VipsPel *) buf ) )
return( -1 );
return( 0 );
}
static void
vips_tonelut_class_init( VipsTonelutClass *class )
{
GObjectClass *gobject_class = G_OBJECT_CLASS( class );
VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
gobject_class->set_property = vips_object_set_property;
gobject_class->get_property = vips_object_get_property;
vobject_class->nickname = "tonelut";
vobject_class->description = _( "build a look-up table" );
vobject_class->build = vips_tonelut_build;
VIPS_ARG_INT( class, "in_max", 4,
_( "In-max" ),
_( "Size of LUT to build" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsTonelut, in_max ),
1, 65535, 32767 );
VIPS_ARG_INT( class, "out_max", 5,
_( "Out-max" ),
_( "Maximum value in output LUT" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsTonelut, out_max ),
1, 65535, 32767 );
VIPS_ARG_DOUBLE( class, "Lb", 6,
_( "Black point" ),
_( "Lowest value in output" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsTonelut, Lb ),
0, 100, 0 );
VIPS_ARG_DOUBLE( class, "Lw", 7,
_( "White point" ),
_( "Highest value in output" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsTonelut, Lw ),
0, 100, 100 );
VIPS_ARG_DOUBLE( class, "Ps", 8,
_( "Shadow point" ),
_( "Position of shadow" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsTonelut, Ps ),
0, 1, 0.2 );
VIPS_ARG_DOUBLE( class, "Pm", 9,
_( "Mid-tone point" ),
_( "Position of mid-tones" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsTonelut, Pm ),
0, 1, 0.5 );
VIPS_ARG_DOUBLE( class, "Ph", 10,
_( "Highlight point" ),
_( "Position of highlights" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsTonelut, Ph ),
0, 1, 0.8 );
VIPS_ARG_DOUBLE( class, "S", 11,
_( "Shadow adjust" ),
_( "Adjust shadows by this much" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsTonelut, S ),
-30, 30, 0 );
VIPS_ARG_DOUBLE( class, "M", 12,
_( "Mid-tone adjust" ),
_( "Adjust mid-tones by this much" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsTonelut, M ),
-30, 30, 0 );
VIPS_ARG_DOUBLE( class, "H", 13,
_( "Highlight adjust" ),
_( "Adjust highlights by this much" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsTonelut, H ),
-30, 30, 0 );
}
static void
vips_tonelut_init( VipsTonelut *lut )
{
lut->in_max = 32767;
lut->out_max = 32767;
lut->Lb = 0.0;
lut->Lw = 100.0;
lut->Ps = 0.2;
lut->Pm = 0.5;
lut->Ph = 0.8;
lut->S = 0.0;
lut->M = 0.0;
lut->H = 0.0;
}
/**
* vips_tonelut:
* @out: (out): output image
* @...: %NULL-terminated list of optional named arguments
*
* Optional arguments:
*
* * @in_max: input range
* * @out_max: output range
* * @Lb: black-point [0-100]
* * @Lw: white-point [0-100]
* * @Ps: shadow point (eg. 0.2)
* * @Pm: mid-tone point (eg. 0.5)
* * @Ph: highlight point (eg. 0.8)
* * @S: shadow adjustment (+/- 30)
* * @M: mid-tone adjustment (+/- 30)
* * @H: highlight adjustment (+/- 30)
*
* vips_tonelut() generates a tone curve for the adjustment of image
* levels. It is mostly designed for adjusting the L* part of a LAB image in
* a way suitable for print work, but you can use it for other things too.
*
* The curve is an unsigned 16-bit image with (@in_max + 1) entries,
* each in the range [0, @out_max].
*
* @Lb, @Lw are expressed as 0-100, as in LAB colour space. You
* specify the scaling for the input and output images with the @in_max and
* @out_max parameters.
*
* Returns: 0 on success, -1 on error
*/
int
vips_tonelut( VipsImage **out, ... )
{
va_list ap;
int result;
va_start( ap, out );
result = vips_call_split( "tonelut", ap, out );
va_end( ap );
return( result );
}
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