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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 <glib/gi18n-lib.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 = 255.0F;
}
else {
/* Center blue.
*/
c_max = p[2];
c_min = VIPS_MIN(p[1], p[0]);
secondary_diff = p[0] - p[1];
wrap_around_hue = 170.0F;
}
}
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 = 0.0F;
}
else {
/* Center green
*/
c_max = p[1];
c_min = VIPS_MIN(p[2], p[0]);
secondary_diff = p[2] - p[0];
wrap_around_hue = 85.0F;
}
}
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: (method)
* @in: input image
* @out: (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 [method@Image.Lab2LCh] for a
* much better colour space.
*
* ::: seealso
* [method@Image.HSV2sRGB], [method@Image.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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