gdouble
gimp_histogram_get_channel (GimpHistogram *histogram,
GimpHistogramChannel channel,
gint bin)
{
g_return_val_if_fail (histogram != NULL, 0.0);
if (histogram->n_channels > 3)
channel++;
return gimp_histogram_get_value (histogram, channel, bin);
}
gdouble
gimp_histogram_get_std_dev (GimpHistogram *histogram,
GimpHistogramChannel channel,
gint start,
gint end)
{
gint i;
gdouble dev = 0.0;
gdouble count;
gdouble mean;
g_return_val_if_fail (histogram != NULL, 0.0);
/* the gray alpha channel is in slot 1 */
if (histogram->n_channels == 3 && channel == GIMP_HISTOGRAM_ALPHA)
channel = 1;
if (! histogram->values ||
start > end ||
(channel == GIMP_HISTOGRAM_RGB && histogram->n_channels < 4) ||
(channel != GIMP_HISTOGRAM_RGB && channel >= histogram->n_channels))
return 0.0;
mean = gimp_histogram_get_mean (histogram, channel, start, end);
count = gimp_histogram_get_count (histogram, channel, start, end);
if (count == 0.0)
count = 1.0;
for (i = start; i <= end; i++)
{
gdouble value;
if (channel == GIMP_HISTOGRAM_RGB)
{
value = (HISTOGRAM_VALUE (GIMP_HISTOGRAM_RED, i) +
HISTOGRAM_VALUE (GIMP_HISTOGRAM_GREEN, i) +
HISTOGRAM_VALUE (GIMP_HISTOGRAM_BLUE, i));
}
else
{
value = gimp_histogram_get_value (histogram, channel, i);
}
dev += value * SQR (i - mean);
}
return sqrt (dev / count);
}
void
gimp_levels_config_stretch_channel (GimpLevelsConfig *config,
GimpHistogram *histogram,
GimpHistogramChannel channel)
{
gdouble count;
gdouble bias = 0.006;
gint n_bins;
gint i;
g_return_if_fail (GIMP_IS_LEVELS_CONFIG (config));
g_return_if_fail (histogram != NULL);
g_object_freeze_notify (G_OBJECT (config));
config->gamma[channel] = 1.0;
config->low_output[channel] = 0.0;
config->high_output[channel] = 1.0;
n_bins = gimp_histogram_n_bins (histogram);
count = gimp_histogram_get_count (histogram, channel, 0, n_bins - 1);
if (count == 0.0)
{
config->low_input[channel] = 0.0;
config->high_input[channel] = 0.0;
}
else
{
gdouble new_count;
gdouble percentage;
gdouble next_percentage;
/* Set the low input */
new_count = 0.0;
for (i = 0; i < (n_bins - 1); i++)
{
new_count += gimp_histogram_get_value (histogram, channel, i);
percentage = new_count / count;
next_percentage = (new_count +
gimp_histogram_get_value (histogram,
channel,
i + 1)) / count;
if (fabs (percentage - bias) < fabs (next_percentage - bias))
{
config->low_input[channel] = (gdouble) (i + 1) / (n_bins - 1);
break;
}
}
/* Set the high input */
new_count = 0.0;
for (i = (n_bins - 1); i > 0; i--)
{
new_count += gimp_histogram_get_value (histogram, channel, i);
percentage = new_count / count;
next_percentage = (new_count +
gimp_histogram_get_value (histogram,
channel,
i - 1)) / count;
if (fabs (percentage - bias) < fabs (next_percentage - bias))
{
config->high_input[channel] = (gdouble) (i - 1) / (n_bins - 1);
break;
}
}
}
g_object_notify (G_OBJECT (config), "gamma");
g_object_notify (G_OBJECT (config), "low-input");
g_object_notify (G_OBJECT (config), "high-input");
g_object_notify (G_OBJECT (config), "low-output");
g_object_notify (G_OBJECT (config), "high-output");
g_object_thaw_notify (G_OBJECT (config));
}
static void
gimp_histogram_view_draw_spike (GimpHistogramView *view,
GimpHistogramChannel channel,
GdkGC *gc,
GdkGC *bg_gc,
gint x,
gint i,
gint j,
gdouble max,
gdouble bg_max,
gint height,
gint border)
{
gdouble value = 0.0;
gdouble bg_value = 0.0;
gint y;
gint bg_y;
if (view->histogram)
{
do
{
gdouble v = gimp_histogram_get_value (view->histogram, channel, i++);
if (v > value)
value = v;
}
while (i < j);
}
if (bg_gc && view->bg_histogram)
{
do
{
gdouble v = gimp_histogram_get_value (view->bg_histogram, channel, i++);
if (v > bg_value)
bg_value = v;
}
while (i < j);
}
if (value <= 0.0 && bg_value <= 0.0)
return;
switch (view->scale)
{
case GIMP_HISTOGRAM_SCALE_LINEAR:
y = (gint) (((height - 2) * value) / max);
bg_y = (gint) (((height - 2) * bg_value) / bg_max);
break;
case GIMP_HISTOGRAM_SCALE_LOGARITHMIC:
y = (gint) (((height - 2) * log (value)) / max);
bg_y = (gint) (((height - 2) * log (bg_value)) / bg_max);
break;
default:
y = 0;
bg_y = 0;
break;
}
if (bg_gc)
gdk_draw_line (GTK_WIDGET (view)->window, bg_gc,
x + border, height + border - 1,
x + border, height + border - bg_y - 1);
gdk_draw_line (GTK_WIDGET (view)->window, gc,
x + border, height + border - 1,
x + border, height + border - y - 1);
}