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gimp/app/base/lut-funcs.c

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/* GIMP - The GNU Image Manipulation Program
* Copyright (C) 1995 Spencer Kimball and Peter Mattis
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU 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.
*/
#include "config.h"
#include <glib-object.h>
#include "libgimpmath/gimpmath.h"
#include "base-types.h"
#include "gimphistogram.h"
#include "gimplut.h"
#include "lut-funcs.h"
/* ---------- Brightness/Contrast -----------*/
typedef struct
{
gdouble brightness;
gdouble contrast;
} BrightnessContrastLutData;
static gfloat
brightness_contrast_lut_func (BrightnessContrastLutData *data,
gint nchannels,
gint channel,
gfloat value)
{
gdouble slant;
/* return the original value for the alpha channel */
if ((nchannels == 2 || nchannels == 4) && channel == nchannels -1)
return value;
/* apply brightness */
if (data->brightness < 0.0)
value = value * (1.0 + data->brightness);
else
value = value + ((1.0 - value) * data->brightness);
slant = tan ((data->contrast + 1) * G_PI_4);
value = (value - 0.5) * slant + 0.5;
return value;
}
void
brightness_contrast_lut_setup (GimpLut *lut,
gdouble brightness,
gdouble contrast,
gint n_channels)
{
BrightnessContrastLutData data;
g_return_if_fail (lut != NULL);
data.brightness = brightness;
data.contrast = contrast;
gimp_lut_setup (lut,
(GimpLutFunc) brightness_contrast_lut_func, &data, n_channels);
}
GimpLut *
brightness_contrast_lut_new (gdouble brightness,
gdouble contrast,
gint n_channels)
{
GimpLut *lut = gimp_lut_new ();
brightness_contrast_lut_setup (lut, brightness, contrast, n_channels);
return lut;
}
/* ---------------- invert ------------------ */
static gfloat
invert_lut_func (gpointer unused,
gint n_channels,
gint channel,
gfloat value)
{
/* don't invert the alpha channel */
if ((n_channels == 2 || n_channels == 4) && channel == n_channels -1)
return value;
return 1.0 - value;
}
static void
invert_lut_setup (GimpLut *lut,
gint n_channels)
{
g_return_if_fail (lut != NULL);
gimp_lut_setup_exact (lut, (GimpLutFunc) invert_lut_func, NULL, n_channels);
}
GimpLut *
invert_lut_new (gint n_channels)
{
GimpLut *lut = gimp_lut_new ();
invert_lut_setup (lut, n_channels);
return lut;
}
/* ---------------- add (or subract)------------------ */
static gfloat
add_lut_func (gdouble *amount,
gint n_channels,
gint channel,
gfloat value)
{
/* don't change the alpha channel */
if ((n_channels == 2 || n_channels == 4) && channel == n_channels -1)
return value;
return (value + *amount);
}
static void
add_lut_setup (GimpLut *lut,
gdouble amount,
gint n_channels)
{
g_return_if_fail (lut != NULL);
gimp_lut_setup (lut, (GimpLutFunc) add_lut_func, &amount, n_channels);
}
GimpLut *
add_lut_new (gdouble amount,
gint n_channels)
{
GimpLut *lut = gimp_lut_new ();
add_lut_setup (lut, amount, n_channels);
return lut;
}
/* ---------------- intersect (MIN (pixel, value)) ------------------ */
static gfloat
intersect_lut_func (gdouble *min,
gint n_channels,
gint channel,
gfloat value)
{
/* don't change the alpha channel */
if ((n_channels == 2 || n_channels == 4) && channel == n_channels -1)
return value;
return MIN (value, *min);
}
static void
intersect_lut_setup (GimpLut *lut,
gdouble value,
gint n_channels)
{
g_return_if_fail (lut != NULL);
gimp_lut_setup_exact (lut,
(GimpLutFunc) intersect_lut_func, &value, n_channels);
}
GimpLut *
intersect_lut_new (gdouble value,
gint n_channels)
{
GimpLut *lut = gimp_lut_new ();
intersect_lut_setup (lut, value, n_channels);
return lut;
}
/* ---------------- Threshold ------------------ */
static gfloat
threshold_lut_func (gdouble *min,
gint n_channels,
gint channel,
gfloat value)
{
/* don't change the alpha channel */
if ((n_channels == 2 || n_channels == 4) && channel == n_channels -1)
return value;
if (value < *min)
return 0.0;
return 1.0;
}
static void
threshold_lut_setup (GimpLut *lut,
gdouble value,
gint n_channels)
{
g_return_if_fail (lut != NULL);
gimp_lut_setup_exact (lut,
(GimpLutFunc) threshold_lut_func, &value, n_channels);
}
GimpLut *
threshold_lut_new (gdouble value,
gint n_channels)
{
GimpLut *lut = gimp_lut_new ();
threshold_lut_setup (lut, value, n_channels);
return lut;
}
/* --------------- posterize ---------------- */
static gfloat
posterize_lut_func (gint *ilevels,
gint n_channels,
gint channel,
gfloat value)
{
gint levels;
/* don't posterize the alpha channel */
if ((n_channels == 2 || n_channels == 4) && channel == n_channels -1)
return value;
if (*ilevels < 2)
levels = 2;
else
levels = *ilevels;
value = RINT (value * (levels - 1.0)) / (levels - 1.0);
return value;
}
void
posterize_lut_setup (GimpLut *lut,
gint levels,
gint n_channels)
{
g_return_if_fail (lut != NULL);
gimp_lut_setup_exact (lut,
(GimpLutFunc) posterize_lut_func, &levels, n_channels);
}
GimpLut *
posterize_lut_new (gint levels,
gint n_channels)
{
GimpLut *lut = gimp_lut_new ();
posterize_lut_setup (lut, levels, n_channels);
return lut;
}
/* --------------- equalize ------------- */
typedef struct
{
GimpHistogram *histogram;
gint part[5][257];
} hist_lut_struct;
static gfloat
equalize_lut_func (hist_lut_struct *hlut,
gint nchannels,
gint channel,
gfloat value)
{
gint i = 0;
gint j;
/* don't equalize the alpha channel */
if ((nchannels == 2 || nchannels == 4) && channel == nchannels - 1)
return value;
j = (gint) (value * 255.0 + 0.5);
while (hlut->part[channel][i + 1] <= j)
i++;
return i / 255.0;
}
static void
equalize_lut_setup (GimpLut *lut,
GimpHistogram *hist,
gint n_channels)
{
gint i, k, j;
hist_lut_struct hlut;
gdouble pixels_per_value;
gdouble desired;
gdouble sum, dif;
g_return_if_fail (lut != NULL);
g_return_if_fail (hist != NULL);
/* Find partition points */
pixels_per_value = gimp_histogram_get_count (hist,
GIMP_HISTOGRAM_VALUE,
0, 255) / 256.0;
for (k = 0; k < n_channels; k++)
{
/* First and last points in partition */
hlut.part[k][0] = 0;
hlut.part[k][256] = 256;
/* Find intermediate points */
j = 0;
sum = (gimp_histogram_get_channel (hist, k, 0) +
gimp_histogram_get_channel (hist, k, 1));
for (i = 1; i < 256; i++)
{
desired = i * pixels_per_value;
while (sum < desired && j < 256)
{
j++;
sum += gimp_histogram_get_channel (hist, k, j + 1);
}
/* Nearest sum */
dif = sum - gimp_histogram_get_channel (hist, k, j);
if ((sum - desired) > (dif / 2.0))
hlut.part[k][i] = j;
else
hlut.part[k][i] = j + 1;
}
}
gimp_lut_setup (lut, (GimpLutFunc) equalize_lut_func, &hlut, n_channels);
}
GimpLut *
equalize_lut_new (GimpHistogram *histogram,
gint n_channels)
{
GimpLut *lut;
g_return_val_if_fail (histogram != NULL, NULL);
lut = gimp_lut_new ();
equalize_lut_setup (lut, histogram, n_channels);
return lut;
}
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