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/* to HSV ... useful for compatibility with other packages
*
* 9/6/15
* - from LabS2Lab.c
*/
/*
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 <vips/intl.h>
#include <stdio.h>
#include <vips/vips.h>
#include "pcolour.h"
typedef VipsColourCode VipssRGB2HSV;
typedef VipsColourCodeClass VipssRGB2HSVClass;
G_DEFINE_TYPE( VipssRGB2HSV, vips_sRGB2HSV, VIPS_TYPE_COLOUR_CODE );
static void
vips_sRGB2HSV_line( VipsColour *colour, VipsPel *out, VipsPel **in, int width )
{
unsigned char *p = (unsigned char *) in[0];
unsigned char *q = (unsigned char *) out;
int i;
for( i = 0; i < width; i++ ) {
unsigned char c_max;
unsigned char c_min;
float secondary_diff;
float wrap_around_hue;
if( p[1] < p[2] ) {
if( p[2] < p[0] ) {
/* Center red (at top).
*/
c_max = p[0];
c_min = p[1];
secondary_diff = p[1] - p[2];
wrap_around_hue = 255.0;
}
else {
/* Center blue.
*/
c_max = p[2];
c_min = VIPS_MIN( p[1], p[0] );
secondary_diff = p[0] - p[1];
wrap_around_hue = 170.0;
}
}
else {
if( p[1] < p[0] ) {
/* Center red (at bottom)
*/
c_max = p[0];
c_min = p[2];
secondary_diff = p[1] - p[2];
wrap_around_hue = 0.0;
}
else {
/* Center green
*/
c_max = p[1];
c_min = VIPS_MIN( p[2], p[0] );
secondary_diff = p[2] - p[0];
wrap_around_hue = 85.0;
}
}
if( c_max == 0 ) {
q[0] = 0;
q[1] = 0;
q[2] = 0;
}
else {
unsigned char delta;
q[2] = c_max;
delta = c_max - c_min;
if( delta == 0 )
q[0] = 0;
else
q[0] = 42.5 * (secondary_diff / (float) delta) +
wrap_around_hue;
q[1] = delta * 255.0 / (float) c_max;
}
p += 3;
q += 3;
}
}
static void
vips_sRGB2HSV_class_init( VipssRGB2HSVClass *class )
{
VipsObjectClass *object_class = (VipsObjectClass *) class;
VipsColourClass *colour_class = VIPS_COLOUR_CLASS( class );
object_class->nickname = "sRGB2HSV";
object_class->description = _( "transform sRGB to HSV" );
colour_class->process_line = vips_sRGB2HSV_line;
}
static void
vips_sRGB2HSV_init( VipssRGB2HSV *sRGB2HSV )
{
VipsColour *colour = VIPS_COLOUR( sRGB2HSV );
VipsColourCode *code = VIPS_COLOUR_CODE( sRGB2HSV );
colour->interpretation = VIPS_INTERPRETATION_HSV;
colour->format = VIPS_FORMAT_UCHAR;
colour->bands = 3;
colour->input_bands = 3;
code->input_coding = VIPS_CODING_NONE;
code->input_format = VIPS_FORMAT_UCHAR;
code->input_interpretation = VIPS_INTERPRETATION_sRGB;
}
/**
* vips_sRGB2HSV:
* @in: input image
* @out: output image
* @...: %NULL-terminated list of optional named arguments
*
* Convert to HSV.
*
* HSV is a crude polar coordinate system for RGB images. It is provided for
* compatibility with other image processing systems. See vips_Lab2LCh() for a
* much better colour space.
*
* See also: vips_HSV2sRGB(), vips_Lab2LCh().
*
* Returns: 0 on success, -1 on error.
*/
int
vips_sRGB2HSV( VipsImage *in, VipsImage **out, ... )
{
va_list ap;
int result;
va_start( ap, out );
result = vips_call_split( "sRGB2HSV", ap, in, out );
va_end( ap );
return( result );
}
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