gimp/app/lut_funcs.c

422 lines
9.7 KiB
C

/* The GIMP -- an 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 <math.h>
#include <stdio.h>
#include <glib.h>
#include "appenv.h"
#include "gimplut.h"
#include "gimphistogram.h"
/* ---------- Brightness/Contrast -----------*/
typedef struct B_C_struct
{
double brightness;
double contrast;
} B_C_struct;
static float
brightness_contrast_lut_func(B_C_struct *data,
int nchannels, int channel, float value)
{
float nvalue;
double power;
/* 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);
/* apply contrast */
if (data->contrast < 0.0)
{
if (value > 0.5)
nvalue = 1.0 - value;
else
nvalue = value;
if (nvalue < 0.0)
nvalue = 0.0;
nvalue = 0.5 * pow (nvalue * 2.0 , (double) (1.0 + data->contrast));
if (value > 0.5)
value = 1.0 - nvalue;
else
value = nvalue;
}
else
{
if (value > 0.5)
nvalue = 1.0 - value;
else
nvalue = value;
if (nvalue < 0.0)
nvalue = 0.0;
power = (data->contrast == 1.0) ? 127 : 1.0 / (1.0 - data->contrast);
nvalue = 0.5 * pow (2.0 * nvalue, power);
if (value > 0.5)
value = 1.0 - nvalue;
else
value = nvalue;
}
return value;
}
void
brightness_contrast_lut_setup(GimpLut *lut, double brightness, double contrast,
int nchannels)
{
B_C_struct data;
data.brightness = brightness;
data.contrast = contrast;
gimp_lut_setup(lut, (GimpLutFunc) brightness_contrast_lut_func,
(void *) &data, nchannels);
}
GimpLut *
brightness_contrast_lut_new(double brightness, double contrast,
int nchannels)
{
GimpLut *lut;
lut = gimp_lut_new();
brightness_contrast_lut_setup(lut, brightness, contrast, nchannels);
return lut;
}
/* ---------------- invert ------------------ */
static float
invert_lut_func(void *unused,
int nchannels, int channel, float value)
{
/* don't invert the alpha channel */
if ((nchannels == 2 || nchannels == 4) && channel == nchannels -1)
return value;
return 1.0 - value;
}
void
invert_lut_setup(GimpLut *lut, int nchannels)
{
gimp_lut_setup_exact(lut, (GimpLutFunc) invert_lut_func,
NULL , nchannels);
}
GimpLut *
invert_lut_new(int nchannels)
{
GimpLut *lut;
lut = gimp_lut_new();
invert_lut_setup(lut, nchannels);
return lut;
}
/* ---------------- add (or subract)------------------ */
static float
add_lut_func(double *ammount,
int nchannels, int channel, float value)
{
/* don't change the alpha channel */
if ((nchannels == 2 || nchannels == 4) && channel == nchannels -1)
return value;
return (value + *ammount);
}
void
add_lut_setup(GimpLut *lut, double ammount, int nchannels)
{
gimp_lut_setup(lut, (GimpLutFunc) add_lut_func,
(void *) &ammount , nchannels);
}
GimpLut *
add_lut_new(double ammount, int nchannels)
{
GimpLut *lut;
lut = gimp_lut_new();
add_lut_setup(lut, ammount, nchannels);
return lut;
}
/* ---------------- intersect (MINIMUM(pixel, value)) ------------------ */
static float
intersect_lut_func(double *min,
int nchannels, int channel, float value)
{
/* don't change the alpha channel */
if ((nchannels == 2 || nchannels == 4) && channel == nchannels -1)
return value;
return MIN(value, *min);
}
void
intersect_lut_setup(GimpLut *lut, double value, int nchannels)
{
gimp_lut_setup_exact(lut, (GimpLutFunc) intersect_lut_func,
(void *) &value , nchannels);
}
GimpLut *
intersect_lut_new(double value, int nchannels)
{
GimpLut *lut;
lut = gimp_lut_new();
intersect_lut_setup(lut, value, nchannels);
return lut;
}
/* ---------------- Threshold ------------------ */
static float
threshold_lut_func(double *min,
int nchannels, int channel, float value)
{
/* don't change the alpha channel */
if ((nchannels == 2 || nchannels == 4) && channel == nchannels -1)
return value;
if (value < *min)
return 0.0;
return 1.0;
}
void
threshold_lut_setup(GimpLut *lut, double value, int nchannels)
{
gimp_lut_setup_exact(lut, (GimpLutFunc) threshold_lut_func,
(void *) &value , nchannels);
}
GimpLut *
threshold_lut_new(double value, int nchannels)
{
GimpLut *lut;
lut = gimp_lut_new();
threshold_lut_setup(lut, value, nchannels);
return lut;
}
/* ------------- levels ------------ */
typedef struct
{
double *gamma;
int *low_input;
int *high_input;
int *low_output;
int *high_output;
} levels_struct;
static float
levels_lut_func(levels_struct *data,
int nchannels, int channel, float value)
{
double inten;
int j;
if (nchannels == 1)
j = 0;
else
j = channel + 1;
inten = value;
/* For color images this runs through the loop with j = channel +1
the first time and j = 0 the second time */
/* For bw images this runs through the loop with j = 0 the first and
only time */
for (; j >= 0; j -= (channel + 1))
{
/* don't apply the overall curve to the alpha channel */
if (j == 0 && (nchannels == 2 || nchannels == 4)
&& channel == nchannels -1)
return inten;
/* determine input intensity */
if (data->high_input[j] != data->low_input[j])
inten = (double) (255.0*inten - data->low_input[j]) /
(double) (data->high_input[j] - data->low_input[j]);
else
inten = (double) (255.0*inten - data->low_input[j]);
if (data->gamma[j] != 0.0)
{
if (inten >= 0.0)
inten = pow ( inten, (1.0 / data->gamma[j]));
else
inten = -pow (-inten, (1.0 / data->gamma[j]));
}
/* determine the output intensity */
if (data->high_output[j] >= data->low_output[j])
inten = (double) (inten * (data->high_output[j] - data->low_output[j]) +
data->low_output[j]);
else if (data->high_output[j] < data->low_output[j])
inten = (double) (data->low_output[j] - inten *
(data->low_output[j] - data->high_output[j]));
inten /= 255.0;
}
return inten;
}
void
levels_lut_setup(GimpLut *lut, double *gamma, int *low_input, int *high_input,
int *low_output, int *high_output, int nchannels)
{
levels_struct data;
data.gamma = gamma;
data.low_input = low_input;
data.high_input = high_input;
data.low_output = low_output;
data.high_output = high_output;
gimp_lut_setup(lut, (GimpLutFunc) levels_lut_func,
(void *) &data, nchannels);
}
GimpLut *
levels_lut_new(double *gamma, int *low_input, int *high_input,
int *low_output, int *high_output, int nchannels)
{
GimpLut *lut;
lut = gimp_lut_new();
levels_lut_setup(lut, gamma, low_input, high_input,
low_output, high_output, nchannels);
return lut;
}
/* --------------- posterize ---------------- */
static float
posterize_lut_func(int *ilevels,
int nchannels, int channel, float value)
{
int levels;
/* don't posterize the alpha channel */
if ((nchannels == 2 || nchannels == 4) && channel == nchannels -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, int levels, int nchannels)
{
gimp_lut_setup_exact(lut, (GimpLutFunc) posterize_lut_func,
(void *) &levels , nchannels);
}
GimpLut *
posterize_lut_new(int levels, int nchannels)
{
GimpLut *lut;
lut = gimp_lut_new();
posterize_lut_setup(lut, levels, nchannels);
return lut;
}
/* --------------- equalize ------------- */
struct hist_lut_struct
{
GimpHistogram *histogram;
int part[5][257];
};
static float
equalize_lut_func(struct hist_lut_struct *hlut,
int nchannels, int channel, float value)
{
int i = 0, j;
j = (int)(value * 255.0 + 0.5);
while (hlut->part[channel][i + 1] <= j)
i++;
return i / 255.0;
}
void
eq_histogram_lut_setup (GimpLut *lut, GimpHistogram *hist, int bytes)
{
int i, k, j;
struct hist_lut_struct hlut;
double pixels_per_value;
double desired;
double sum, dif;
/* Find partition points */
pixels_per_value = gimp_histogram_get_count(hist, 0, 255) / 256.0;
for (k = 0; k < bytes; 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++;
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,
(void *) &hlut, bytes);
}
GimpLut *
eq_histogram_lut_new(GimpHistogram *h, int nchannels)
{
GimpLut *lut;
lut = gimp_lut_new();
eq_histogram_lut_setup(lut, h, nchannels);
return lut;
}