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add vips_unpremultiply()

This commit is contained in:
John Cupitt 2015-05-08 10:26:23 +01:00
parent 66c51b7d23
commit 472bf7dbc3
6 changed files with 389 additions and 65 deletions
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1
ChangeLog
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@ -1,4 +1,5 @@
7/5/15 started 8.1.0
- add vips_premultiply(), vips_unpremultiply()
4/5/15 started 8.0.2
- fix a refcount error in C++ wrapper, thanks huskier

1
libvips/conversion/Makefile.am
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@ -8,6 +8,7 @@ libconversion_la_SOURCES = \
sequential.c \
flatten.c \
premultiply.c \
unpremultiply.c \
cache.c \
copy.c \
embed.c \

2
libvips/conversion/conversion.c
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@ -239,6 +239,7 @@ vips_conversion_operation_init( void )
extern GType vips_bandmean_get_type( void );
extern GType vips_flatten_get_type( void );
extern GType vips_premultiply_get_type( void );
extern GType vips_unpremultiply_get_type( void );
extern GType vips_bandbool_get_type( void );
extern GType vips_gaussnoise_get_type( void );
extern GType vips_grid_get_type( void );
@ -279,6 +280,7 @@ vips_conversion_operation_init( void )
vips_bandmean_get_type();
vips_flatten_get_type();
vips_premultiply_get_type();
vips_unpremultiply_get_type();
vips_bandbool_get_type();
vips_gaussnoise_get_type();
vips_grid_get_type();

95
libvips/conversion/premultiply.c
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@ -1,4 +1,4 @@
/* premultiply and unpremultiply alpha
/* premultiply alpha
*
* Author: John Cupitt
* Written on: 7/5/15
@ -57,42 +57,24 @@ typedef struct _VipsPremultiply {
VipsImage *in;
/* Set for the inverse transform (divide, or unpremultiply).
*/
gboolean unpremultiply;
} VipsPremultiply;
typedef VipsConversionClass VipsPremultiplyClass;
G_DEFINE_TYPE( VipsPremultiply, vips_premultiply, VIPS_TYPE_CONVERSION );
/* Pre and unpre ops.
*/
#define PRE_MULTIPLY( Q, P ) { \
(Q) = (P) * nalpha; \
}
#define UNPRE_MULTIPLY( Q, P ) { \
if( clip_alpha == 0 ) \
(Q) = 0.0; \
else \
(Q) = (P) / nalpha; \
}
/* Premultiply a greyscale (two band) image.
*/
#define PRE_GREY( IN, OUT, OP ) { \
#define PRE_GREY( IN, OUT ) { \
IN * restrict p = (IN *) in; \
OUT * restrict q = (OUT *) out; \
\
for( x = 0; x < width; x++ ) { \
IN alpha = p[1]; \
int clip_alpha = VIPS_CLIP( 0, alpha, max_value ); \
double nalpha = clip_alpha / max_value; \
double nalpha = (double) clip_alpha / max_value; \
\
OP( q[0], p[0] ); \
q[0] = p[0] * nalpha; \
q[1] = alpha; \
\
p += 2; \
@ -102,18 +84,18 @@ G_DEFINE_TYPE( VipsPremultiply, vips_premultiply, VIPS_TYPE_CONVERSION );
/* Premultiply an RGB (four band) image.
*/
#define PRE_RGB( IN, OUT, OP ) { \
#define PRE_RGB( IN, OUT ) { \
IN * restrict p = (IN *) in; \
OUT * restrict q = (OUT *) out; \
\
for( x = 0; x < width; x++ ) { \
IN alpha = p[3]; \
int clip_alpha = VIPS_CLIP( 0, alpha, max_value ); \
double nalpha = clip_alpha / max_value; \
double nalpha = (double) clip_alpha / max_value; \
\
OP( q[0], p[0] ); \
OP( q[1], p[1] ); \
OP( q[2], p[2] ); \
q[0] = p[0] * nalpha; \
q[1] = p[1] * nalpha; \
q[2] = p[2] * nalpha; \
q[3] = alpha; \
\
p += 4; \
@ -123,19 +105,19 @@ G_DEFINE_TYPE( VipsPremultiply, vips_premultiply, VIPS_TYPE_CONVERSION );
/* Premultiply a CMYK (five band) image.
*/
#define PRE_CMYK( IN, OUT, OP ) { \
#define PRE_CMYK( IN, OUT ) { \
IN * restrict p = (IN *) in; \
OUT * restrict q = (OUT *) out; \
\
for( x = 0; x < width; x++ ) { \
IN alpha = p[4]; \
int clip_alpha = VIPS_CLIP( 0, alpha, max_value ); \
double nalpha = clip_alpha / max_value; \
double nalpha = (double) clip_alpha / max_value; \
\
OP( q[0], p[0] ); \
OP( q[1], p[1] ); \
OP( q[2], p[2] ); \
OP( q[3], p[3] ); \
q[0] = p[0] * nalpha; \
q[1] = p[1] * nalpha; \
q[2] = p[2] * nalpha; \
q[3] = p[3] * nalpha; \
q[4] = alpha; \
\
p += 5; \
@ -143,24 +125,15 @@ G_DEFINE_TYPE( VipsPremultiply, vips_premultiply, VIPS_TYPE_CONVERSION );
} \
}
#define PRE_OP( IN, OUT, OP ) { \
#define PRE( IN, OUT ) { \
if( bands == 2 ) { \
PRE_GREY( IN, OUT, OP ); \
PRE_GREY( IN, OUT ); \
} \
else if( bands == 4 ) { \
PRE_RGB( IN, OUT, OP ); \
PRE_RGB( IN, OUT ); \
} \
else { \
PRE_CMYK( IN, OUT, OP ); \
} \
}
#define PRE( IN, OUT ) { \
if( premultiply->unpremultiply ) { \
PRE_OP( IN, OUT, UNPRE_MULTIPLY ); \
} \
else { \
PRE_OP( IN, OUT, PRE_MULTIPLY ); \
PRE_CMYK( IN, OUT ); \
} \
}
@ -170,7 +143,6 @@ vips_premultiply_gen( VipsRegion *or, void *vseq, void *a, void *b,
{
VipsRegion *ir = (VipsRegion *) vseq;
VipsImage *im = ir->im;
VipsPremultiply *premultiply = (VipsPremultiply *) b;
VipsRect *r = &or->valid;
int width = r->width;
int bands = im->Bands;
@ -307,12 +279,6 @@ vips_premultiply_class_init( VipsPremultiplyClass *class )
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsPremultiply, in ) );
VIPS_ARG_BOOL( class, "unpremultiply", 2,
_( "Unpremultiply" ),
_( "Reverse transform" ),
VIPS_ARGUMENT_OPTIONAL_INPUT,
G_STRUCT_OFFSET( VipsPremultiply, unpremultiply ),
FALSE );
}
static void
@ -326,28 +292,27 @@ vips_premultiply_init( VipsPremultiply *premultiply )
* @out: output image
* @...: %NULL-terminated list of optional named arguments
*
* Optional arguments:
*
* @unpremultiply: %gboolean, set this to reverse the transform
*
* Premultiplies any alpha channel. If @in is an 8-bit RGBA image, @out will
* also have four bands, where:
*
* |[
* n = in[3] / 255; // normalised alpha
* n = in[3] / 255.0; // normalised alpha
* out = [in[0] * n, in[1] * n, in[2] * n, in[3]];
* |]
*
* So the RGB bands are scaled by alpha, alpha is untouched. The result is
* always #VIPS_FORMAT_FLOAT. If you set @unpremultiply, the inverse operation
* is performed, so RGB are divided by normalised alpha. If there is no alpha,
* So the RGB bands are scaled by alpha, alpha is untouched.
* The result is
* #VIPS_FORMAT_FLOAT unless the input format is #VIPS_FORMAT_DOUBLE, in which
* case the output is double as well.
* If there is no alpha,
* the image is passed through unaltered.
*
* The operation works for 1 - 5 band images, from greyscale to CMYKA. 16-bit
* unsigned int image are assumed to have a 16-bit alpha, all other images are
* expected to have 0 - 255 alpha.
* The operation works for 1 - 5 band images, from greyscale to CMYKA.
* If interpretation is #VIPS_INTERPRETATION_GREY16 or
* #VIPS_INTERPRETATION_RGB16, alpha is assumed to have a 0 - 65535 range.
* Otherwise alpha is assumed to have a 0 - 255 range.
*
* See also: vips_flatten().
* See also: vips_unpremultiply(), vips_flatten().
*
* Returns: 0 on success, -1 on error
*/

352
libvips/conversion/unpremultiply.c Normal file
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@ -0,0 +1,352 @@
/* unpremultiply alpha
*
* Author: John Cupitt
* Written on: 7/5/15
*
*/
/*
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
*/
/*
#define VIPS_DEBUG
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <vips/vips.h>
#include <vips/internal.h>
#include <vips/debug.h>
#include "pconversion.h"
typedef struct _VipsUnpremultiply {
VipsConversion parent_instance;
VipsImage *in;
} VipsUnpremultiply;
typedef VipsConversionClass VipsUnpremultiplyClass;
G_DEFINE_TYPE( VipsUnpremultiply, vips_unpremultiply, VIPS_TYPE_CONVERSION );
/* Unpremultiply a greyscale (two band) image.
*/
#define UNPRE_GREY( IN, OUT ) { \
IN * restrict p = (IN *) in; \
OUT * restrict q = (OUT *) out; \
\
for( x = 0; x < width; x++ ) { \
IN alpha = p[1]; \
int clip_alpha = VIPS_CLIP( 0, alpha, max_value ); \
double nalpha = (double) clip_alpha / max_value; \
\
if( clip_alpha == 0 ) \
q[0] = 0; \
else \
q[0] = p[0] / nalpha; \
q[1] = clip_alpha; \
\
p += 2; \
q += 2; \
} \
}
/* Unpremultiply an RGB (four band) image.
*/
#define UNPRE_RGB( IN, OUT ) { \
IN * restrict p = (IN *) in; \
OUT * restrict q = (OUT *) out; \
\
for( x = 0; x < width; x++ ) { \
IN alpha = p[3]; \
int clip_alpha = VIPS_CLIP( 0, alpha, max_value ); \
double nalpha = (double) clip_alpha / max_value; \
\
if( clip_alpha == 0 ) { \
q[0] = 0; \
q[1] = 0; \
q[2] = 0; \
} \
else { \
q[0] = p[0] / nalpha; \
q[1] = p[1] / nalpha; \
q[2] = p[2] / nalpha; \
} \
q[3] = clip_alpha; \
\
p += 4; \
q += 4; \
} \
}
/* Unpremultiply a CMYK (five band) image.
*/
#define UNPRE_CMYK( IN, OUT ) { \
IN * restrict p = (IN *) in; \
OUT * restrict q = (OUT *) out; \
\
for( x = 0; x < width; x++ ) { \
IN alpha = p[4]; \
int clip_alpha = VIPS_CLIP( 0, alpha, max_value ); \
double nalpha = (double) clip_alpha / max_value; \
\
if( clip_alpha == 0 ) { \
q[0] = 0; \
q[1] = 0; \
q[2] = 0; \
q[3] = 0; \
} \
else { \
q[0] = p[0] / nalpha; \
q[1] = p[1] / nalpha; \
q[2] = p[2] / nalpha; \
q[3] = p[3] / nalpha; \
} \
q[4] = clip_alpha; \
\
p += 5; \
q += 5; \
} \
}
#define UNPRE( IN, OUT ) { \
if( bands == 2 ) { \
UNPRE_GREY( IN, OUT ); \
} \
else if( bands == 4 ) { \
UNPRE_RGB( IN, OUT ); \
} \
else { \
UNPRE_CMYK( IN, OUT ); \
} \
}
static int
vips_unpremultiply_gen( VipsRegion *or, void *vseq, void *a, void *b,
gboolean *stop )
{
VipsRegion *ir = (VipsRegion *) vseq;
VipsImage *im = ir->im;
VipsRect *r = &or->valid;
int width = r->width;
int bands = im->Bands;
int max_value;
int x, y;
if( vips_region_prepare( ir, r ) )
return( -1 );
if( im->Type == VIPS_INTERPRETATION_GREY16 ||
im->Type == VIPS_INTERPRETATION_RGB16 )
max_value = 65535;
else
max_value = 255;
for( y = 0; y < r->height; y++ ) {
VipsPel *in = VIPS_REGION_ADDR( ir, r->left, r->top + y );
VipsPel *out = VIPS_REGION_ADDR( or, r->left, r->top + y );
switch( im->BandFmt ) {
case VIPS_FORMAT_UCHAR:
UNPRE( unsigned char, float );
break;
case VIPS_FORMAT_CHAR:
UNPRE( signed char, float );
break;
case VIPS_FORMAT_USHORT:
UNPRE( unsigned short, float );
break;
case VIPS_FORMAT_SHORT:
UNPRE( signed short, float );
break;
case VIPS_FORMAT_UINT:
UNPRE( unsigned int, float );
break;
case VIPS_FORMAT_INT:
UNPRE( signed int, float );
break;
case VIPS_FORMAT_FLOAT:
UNPRE( float, float );
break;
case VIPS_FORMAT_DOUBLE:
UNPRE( double, double );
break;
case VIPS_FORMAT_COMPLEX:
case VIPS_FORMAT_DPCOMPLEX:
default:
g_assert( 0 );
}
}
return( 0 );
}
static int
vips_unpremultiply_build( VipsObject *object )
{
VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
VipsConversion *conversion = VIPS_CONVERSION( object );
VipsUnpremultiply *unpremultiply = (VipsUnpremultiply *) object;
VipsImage **t = (VipsImage **) vips_object_local_array( object, 1 );
VipsImage *in;
if( VIPS_OBJECT_CLASS( vips_unpremultiply_parent_class )->
build( object ) )
return( -1 );
in = unpremultiply->in;
if( vips_image_decode( in, &t[0] ) )
return( -1 );
in = t[0];
/* Trivial case: fall back to copy().
*/
if( in->Bands == 1 ||
in->Bands == 3 ||
(in->Bands == 4 &&
in->Type == VIPS_INTERPRETATION_CMYK) )
return( vips_image_write( in, conversion->out ) );
if( vips_check_noncomplex( class->nickname, in ) )
return( -1 );
if( vips_image_pipelinev( conversion->out,
VIPS_DEMAND_STYLE_THINSTRIP, in, NULL ) )
return( -1 );
if( in->BandFmt == VIPS_FORMAT_DOUBLE )
conversion->out->BandFmt = VIPS_FORMAT_DOUBLE;
else
conversion->out->BandFmt = VIPS_FORMAT_FLOAT;
if( vips_image_generate( conversion->out,
vips_start_one, vips_unpremultiply_gen, vips_stop_one,
in, unpremultiply ) )
return( -1 );
return( 0 );
}
static void
vips_unpremultiply_class_init( VipsUnpremultiplyClass *class )
{
GObjectClass *gobject_class = G_OBJECT_CLASS( class );
VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
VipsOperationClass *operation_class = VIPS_OPERATION_CLASS( class );
VIPS_DEBUG_MSG( "vips_unpremultiply_class_init\n" );
gobject_class->set_property = vips_object_set_property;
gobject_class->get_property = vips_object_get_property;
vobject_class->nickname = "unpremultiply";
vobject_class->description = _( "unpremultiply image alpha" );
vobject_class->build = vips_unpremultiply_build;
operation_class->flags = VIPS_OPERATION_SEQUENTIAL_UNBUFFERED;
VIPS_ARG_IMAGE( class, "in", 1,
_( "Input" ),
_( "Input image" ),
VIPS_ARGUMENT_REQUIRED_INPUT,
G_STRUCT_OFFSET( VipsUnpremultiply, in ) );
}
static void
vips_unpremultiply_init( VipsUnpremultiply *unpremultiply )
{
}
/**
* vips_unpremultiply:
* @in: input image
* @out: output image
* @...: %NULL-terminated list of optional named arguments
*
* Unpremultiplies any alpha channel. If @in is a four-band RGBA image, @out
* will also have four bands, where:
*
* |[
* alpha = (unsigned char) clip( 0, in[3], 255 ); // clip alphha range
* n = alpha / 255; // normalised alpha
* if( n == 0 )
* out = [0, 0, 0, in[3]];
* else
* out = [in[0] / n, in[1] / n, in[2] / n, in[3]];
* |]
*
* So the RGB bands are divided by alpha, alpha is untouched.
* The result is
* #VIPS_FORMAT_FLOAT unless the input format is #VIPS_FORMAT_DOUBLE, in which
* case the output is double as well.
* If there is no alpha,
* the image is passed through unaltered.
*
* The operation works for 1 - 5 band images, from greyscale to CMYKA.
* If interpretation is #VIPS_INTERPRETATION_GREY16 or
* #VIPS_INTERPRETATION_RGB16, alpha is assumed to have a 0 - 65535 range.
* Otherwise alpha is assumed to have a 0 - 255 range.
*
* See also: vips_premultiply(), vips_flatten().
*
* Returns: 0 on success, -1 on error
*/
int
vips_unpremultiply( VipsImage *in, VipsImage **out, ... )
{
va_list ap;
int result;
va_start( ap, out );
result = vips_call_split( "unpremultiply", ap, in, out );
va_end( ap );
return( result );
}

3
libvips/include/vips/conversion.h
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@ -184,10 +184,13 @@ int vips_recomb( VipsImage *in, VipsImage **out, VipsImage *m, ... )
int vips_ifthenelse( VipsImage *cond, VipsImage *in1, VipsImage *in2,
VipsImage **out, ... )
__attribute__((sentinel));
int vips_flatten( VipsImage *in, VipsImage **out, ... )
__attribute__((sentinel));
int vips_premultiply( VipsImage *in, VipsImage **out, ... )
__attribute__((sentinel));
int vips_unpremultiply( VipsImage *in, VipsImage **out, ... )
__attribute__((sentinel));
int vips_falsecolour( VipsImage *in, VipsImage **out, ... )
__attribute__((sentinel));