[gthumb] adjust contrast: reduced the number of filters

[Paolo Bacchilega <paobac src gnome org>]

commit 63d3c6545c6bb5446f970a5f15a85ff8f3977a5d
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Mon Dec 22 18:09:37 2014 +0100

    adjust contrast: reduced the number of filters

 .../file_tools/gth-file-tool-adjust-contrast.c     |   55 ++++++++++++--------
 1 files changed, 33 insertions(+), 22 deletions(-)
---
diff --git a/extensions/file_tools/gth-file-tool-adjust-contrast.c 
b/extensions/file_tools/gth-file-tool-adjust-contrast.c
index 4c81ebd..94e7e6e 100644
--- a/extensions/file_tools/gth-file-tool-adjust-contrast.c
+++ b/extensions/file_tools/gth-file-tool-adjust-contrast.c
@@ -30,8 +30,8 @@
 #define GET_WIDGET(x) (_gtk_builder_get_widget (self->priv->builder, (x)))
 #define APPLY_DELAY 150
 #define PREVIEW_SIZE 0.9
-#define HISTOGRAM_CROP 0.005 /* ignores the 0.5% on each side of the adjust_contrast */
-#define HISTOGRAM_CROP_MAX 0.015 /* ignores the 1.5% on each side of the adjust_contrast */
+#define HISTOGRAM_CROP_0_5 0.005 /* ignores the 0.5% on each side of the histogram */
+#define HISTOGRAM_CROP_1_5 0.015 /* ignores the 1.5% on each side of the histogram */
 
 
 G_DEFINE_TYPE (GthFileToolAdjustContrast, gth_file_tool_adjust_contrast, GTH_TYPE_IMAGE_VIEWER_PAGE_TOOL)
@@ -39,7 +39,8 @@ G_DEFINE_TYPE (GthFileToolAdjustContrast, gth_file_tool_adjust_contrast, GTH_TYP
 
 typedef enum {
        METHOD_STRETCH,
-       METHOD_STRETCH_MAX,
+       METHOD_STRETCH_0_5,
+       METHOD_STRETCH_1_5,
        METHOD_EQUALIZE_LINEAR,
        METHOD_EQUALIZE_SQUARE_ROOT
 } Method;
@@ -90,10 +91,14 @@ get_histogram_value (GthHistogram        *histogram,
                     Method               method)
 {
        double h = gth_histogram_get_value (histogram, channel, bin);
-       if (method == METHOD_EQUALIZE_SQUARE_ROOT)
+       switch (method) {
+       case METHOD_EQUALIZE_SQUARE_ROOT:
                return (h >= 2) ? sqrt (h) : h;
-       else
+       case METHOD_EQUALIZE_LINEAR:
                return h;
+       default:
+               g_assert_not_reached ();
+       }
 }
 
 
@@ -140,13 +145,21 @@ get_value_map_for_stretch (GthHistogram *histogram,
        int    c, v;
 
        n_pixels = gth_histogram_get_n_pixels (histogram);
-       if (method == METHOD_STRETCH) {
-               lower_limit = n_pixels * HISTOGRAM_CROP;
-               higher_limit = n_pixels * (1 - HISTOGRAM_CROP);
-       }
-       else {
-               lower_limit = n_pixels * HISTOGRAM_CROP_MAX;
-               higher_limit = n_pixels * (1 - HISTOGRAM_CROP_MAX);
+       switch (method) {
+       case METHOD_STRETCH:
+               lower_limit = 0;
+               higher_limit = n_pixels;
+               break;
+       case METHOD_STRETCH_0_5:
+               lower_limit = n_pixels * HISTOGRAM_CROP_0_5;
+               higher_limit = n_pixels * (1 - HISTOGRAM_CROP_0_5);
+               break;
+       case METHOD_STRETCH_1_5:
+               lower_limit = n_pixels * HISTOGRAM_CROP_1_5;
+               higher_limit = n_pixels * (1 - HISTOGRAM_CROP_1_5);
+               break;
+       default:
+               g_assert_not_reached ();
        }
 
        value_map = g_new (long *, GTH_HISTOGRAM_N_CHANNELS);
@@ -198,7 +211,8 @@ adjust_contrast_setup (EqualizeData    *equalize_data,
        gth_histogram_calculate_for_image (histogram, source);
        switch (equalize_data->method) {
        case METHOD_STRETCH:
-       case METHOD_STRETCH_MAX:
+       case METHOD_STRETCH_0_5:
+       case METHOD_STRETCH_1_5:
                equalize_data->value_map = get_value_map_for_stretch (histogram, equalize_data->method);
                break;
        case METHOD_EQUALIZE_LINEAR:
@@ -522,10 +536,9 @@ gth_file_tool_adjust_contrast_get_options (GthFileTool *base)
        gtk_widget_show (options);
 
        filter_grid = gth_filter_grid_new ();
-       gth_filter_grid_add_filter (GTH_FILTER_GRID (filter_grid), METHOD_STRETCH, NULL, _("Stretch (0.5%)"), 
NULL);
-       gth_filter_grid_add_filter (GTH_FILTER_GRID (filter_grid), METHOD_STRETCH_MAX, NULL, _("Stretch 
(1.0%)"), NULL);
-       gth_filter_grid_add_filter (GTH_FILTER_GRID (filter_grid), METHOD_EQUALIZE_SQUARE_ROOT, NULL, 
_("Equalize"), NULL);
-       gth_filter_grid_add_filter (GTH_FILTER_GRID (filter_grid), METHOD_EQUALIZE_LINEAR, NULL, _("Equalize 
(Linear)"), NULL);
+       gth_filter_grid_add_filter (GTH_FILTER_GRID (filter_grid), METHOD_STRETCH_0_5, NULL, _("Stretch"), 
_("Stretch the histogram trimming the 0.5%"));
+       gth_filter_grid_add_filter (GTH_FILTER_GRID (filter_grid), METHOD_EQUALIZE_SQUARE_ROOT, NULL, 
_("Equalize"), _("Equalize the histogram using the square root function"));
+       gth_filter_grid_add_filter (GTH_FILTER_GRID (filter_grid), METHOD_EQUALIZE_LINEAR, NULL, 
_("Uniform"), _("Equalize the histogram using the linear function"));
 
        g_signal_connect (filter_grid,
                          "activated",
@@ -547,14 +560,12 @@ gth_file_tool_adjust_contrast_get_options (GthFileTool *base)
        self->priv->preview_tool = gth_preview_tool_new ();
        gth_preview_tool_set_image (GTH_PREVIEW_TOOL (self->priv->preview_tool), self->priv->preview);
        gth_image_viewer_set_tool (GTH_IMAGE_VIEWER (viewer), self->priv->preview_tool);
-       gth_filter_grid_activate (GTH_FILTER_GRID (filter_grid), METHOD_STRETCH);
+       gth_filter_grid_activate (GTH_FILTER_GRID (filter_grid), METHOD_STRETCH_0_5);
 
        gth_filter_grid_generate_previews (GTH_FILTER_GRID (filter_grid),
                                           source,
-                                          METHOD_STRETCH,
-                                          get_image_task_for_method (METHOD_STRETCH),
-                                          METHOD_STRETCH_MAX,
-                                          get_image_task_for_method (METHOD_STRETCH_MAX),
+                                          METHOD_STRETCH_0_5,
+                                          get_image_task_for_method (METHOD_STRETCH_0_5),
                                           METHOD_EQUALIZE_SQUARE_ROOT,
                                           get_image_task_for_method (METHOD_EQUALIZE_SQUARE_ROOT),
                                           METHOD_EQUALIZE_LINEAR,