mirror of https://github.com/GNOME/gimp.git
317 lines
8.5 KiB
C
317 lines
8.5 KiB
C
/* The GIMP -- an image manipulation program
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* Copyright (C) 1995 Spencer Kimball and Peter Mattis
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include "config.h"
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#include <glib-object.h>
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#include "libgimpmath/gimpmath.h"
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#include "libgimpcolor/gimpcolortypes.h"
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#include "libgimpcolor/gimprgb.h"
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#include "base-types.h"
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#include "gimphistogram.h"
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#include "levels.h"
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/* public functions */
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void
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levels_init (Levels *levels)
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{
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GimpHistogramChannel channel;
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g_return_if_fail (levels != NULL);
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for (channel = GIMP_HISTOGRAM_VALUE;
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channel <= GIMP_HISTOGRAM_ALPHA;
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channel++)
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{
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levels_channel_reset (levels, channel);
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}
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}
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void
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levels_channel_reset (Levels *levels,
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GimpHistogramChannel channel)
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{
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g_return_if_fail (levels != NULL);
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levels->gamma[channel] = 1.0;
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levels->low_input[channel] = 0;
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levels->high_input[channel] = 255;
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levels->low_output[channel] = 0;
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levels->high_output[channel] = 255;
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}
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void
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levels_stretch (Levels *levels,
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GimpHistogram *hist,
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gboolean is_color)
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{
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GimpHistogramChannel channel;
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g_return_if_fail (levels != NULL);
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g_return_if_fail (hist != NULL);
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if (is_color)
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{
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/* Set the overall value to defaults */
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levels_channel_reset (levels, GIMP_HISTOGRAM_VALUE);
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for (channel = GIMP_HISTOGRAM_RED;
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channel <= GIMP_HISTOGRAM_BLUE;
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channel++)
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levels_channel_stretch (levels, hist, channel);
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}
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else
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{
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levels_channel_stretch (levels, hist, GIMP_HISTOGRAM_VALUE);
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}
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}
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void
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levels_channel_stretch (Levels *levels,
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GimpHistogram *hist,
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GimpHistogramChannel channel)
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{
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gint i;
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gdouble count, new_count, percentage, next_percentage;
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g_return_if_fail (levels != NULL);
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g_return_if_fail (hist != NULL);
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levels->gamma[channel] = 1.0;
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levels->low_output[channel] = 0;
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levels->high_output[channel] = 255;
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count = gimp_histogram_get_count (hist, channel, 0, 255);
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if (count == 0.0)
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{
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levels->low_input[channel] = 0;
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levels->high_input[channel] = 0;
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}
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else
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{
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/* Set the low input */
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new_count = 0.0;
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for (i = 0; i < 255; i++)
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{
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new_count += gimp_histogram_get_value (hist, channel, i);
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percentage = new_count / count;
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next_percentage =
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(new_count + gimp_histogram_get_value (hist,
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channel,
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i + 1)) / count;
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if (fabs (percentage - 0.006) < fabs (next_percentage - 0.006))
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{
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levels->low_input[channel] = i + 1;
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break;
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}
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}
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/* Set the high input */
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new_count = 0.0;
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for (i = 255; i > 0; i--)
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{
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new_count += gimp_histogram_get_value (hist, channel, i);
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percentage = new_count / count;
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next_percentage =
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(new_count + gimp_histogram_get_value (hist,
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channel,
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i - 1)) / count;
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if (fabs (percentage - 0.006) < fabs (next_percentage - 0.006))
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{
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levels->high_input[channel] = i - 1;
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break;
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}
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}
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}
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}
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static gint
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levels_input_from_color (GimpHistogramChannel channel,
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guchar *color)
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{
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switch (channel)
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{
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case GIMP_HISTOGRAM_VALUE:
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return MAX (MAX (color[RED_PIX], color[GREEN_PIX]), color[BLUE_PIX]);
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case GIMP_HISTOGRAM_RED:
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return color[RED_PIX];
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case GIMP_HISTOGRAM_GREEN:
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return color[GREEN_PIX];
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case GIMP_HISTOGRAM_BLUE:
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return color[BLUE_PIX];
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case GIMP_HISTOGRAM_ALPHA:
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return color[ALPHA_PIX];
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case GIMP_HISTOGRAM_RGB:
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return MIN (MIN (color[RED_PIX], color[GREEN_PIX]), color[BLUE_PIX]);
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}
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return 0; /* just to please the compiler */
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}
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void
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levels_adjust_by_colors (Levels *levels,
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GimpHistogramChannel channel,
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guchar *black,
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guchar *gray,
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guchar *white)
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{
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g_return_if_fail (levels != NULL);
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if (black)
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levels->low_input[channel] = levels_input_from_color (channel, black);
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if (white)
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levels->high_input[channel] = levels_input_from_color (channel, white);
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if (gray)
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{
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gint input;
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gint range;
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gdouble inten;
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gdouble out_light;
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guchar lightness;
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/* Calculate lightness value */
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lightness = GIMP_RGB_LUMINANCE (gray[0], gray[1], gray[2]);
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input = levels_input_from_color (channel, gray);
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range = levels->high_input[channel] - levels->low_input[channel];
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if (range <= 0)
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return;
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input -= levels->low_input[channel];
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if (input < 0)
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return;
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/* Normalize input and lightness */
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inten = (gdouble) input / (gdouble) range;
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out_light = (gdouble) lightness/ (gdouble) range;
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if (out_light <= 0)
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return;
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/* Map selected color to corresponding lightness */
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levels->gamma[channel] = log (inten) / log (out_light);
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}
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}
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void
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levels_calculate_transfers (Levels *levels)
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{
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gdouble inten;
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gint i, j;
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g_return_if_fail (levels != NULL);
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/* Recalculate the levels arrays */
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for (j = 0; j < 5; j++)
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{
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for (i = 0; i < 256; i++)
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{
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/* determine input intensity */
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if (levels->high_input[j] != levels->low_input[j])
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{
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inten = ((gdouble) (i - levels->low_input[j]) /
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(double) (levels->high_input[j] - levels->low_input[j]));
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}
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else
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{
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inten = (gdouble) (i - levels->low_input[j]);
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}
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inten = CLAMP (inten, 0.0, 1.0);
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if (levels->gamma[j] != 0.0)
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inten = pow (inten, (1.0 / levels->gamma[j]));
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levels->input[j][i] = (guchar) (inten * 255.0 + 0.5);
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}
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}
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}
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gfloat
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levels_lut_func (Levels *levels,
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gint n_channels,
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gint channel,
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gfloat value)
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{
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gdouble inten;
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gint j;
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if (n_channels <= 2)
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j = channel;
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else
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j = channel + 1;
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inten = value;
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/* For RGB and RGBA images this runs through the loop with j = channel + 1
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* the first time and j = 0 the second time
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*
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* For GRAY images this runs through the loop with j = 0 the first and
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* only time
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*/
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for (; j >= 0; j -= (channel + 1))
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{
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/* don't apply the overall curve to the alpha channel */
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if (j == 0 && (n_channels == 2 || n_channels == 4) &&
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channel == n_channels - 1)
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return inten;
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/* determine input intensity */
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if (levels->high_input[j] != levels->low_input[j])
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{
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inten = ((gdouble) (255.0 * inten - levels->low_input[j]) /
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(gdouble) (levels->high_input[j] - levels->low_input[j]));
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}
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else
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{
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inten = (gdouble) (255.0 * inten - levels->low_input[j]);
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}
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if (levels->gamma[j] != 0.0)
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{
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if (inten >= 0.0)
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inten = pow ( inten, (1.0 / levels->gamma[j]));
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else
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inten = -pow (-inten, (1.0 / levels->gamma[j]));
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}
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/* determine the output intensity */
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if (levels->high_output[j] >= levels->low_output[j])
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inten = (gdouble) (inten * (levels->high_output[j] -
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levels->low_output[j]) +
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levels->low_output[j]);
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else if (levels->high_output[j] < levels->low_output[j])
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inten = (gdouble) (levels->low_output[j] - inten *
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(levels->low_output[j] - levels->high_output[j]));
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inten /= 255.0;
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}
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return inten;
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}
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