Made the box colors in imglab spread more evenly over the color space.

tools/imglab/src/main.cpp

@@ -20,7 +20,7 @@
 #include <dlib/dir_nav.h>
 
 
-const char* VERSION = "1.11";
+const char* VERSION = "1.12";
 
 const int JPEG_QUALITY = 90;
 

tools/imglab/src/metadata_editor.cpp

@@ -19,27 +19,6 @@ using namespace dlib;
 
 extern const char* VERSION;
 
-rgb_alpha_pixel string_to_color(
-    const std::string& str
-)
-{
-    if (str.size() == 0)
-    {
-        return rgb_alpha_pixel(255,0,0,255);
-    }
-    else
-    {
-        // make up a random color based on the string label.
-        hsi_pixel pix;
-        pix.h = static_cast<unsigned char>(dlib::hash(str)&0xFF); 
-        pix.s = 255;
-        pix.i = 150;
-        rgb_alpha_pixel result;
-        assign_pixel(result, pix);
-        return result;
-    }
-}
-
 // ----------------------------------------------------------------------------------------
 
 metadata_editor::
@@ -78,6 +57,7 @@ metadata_editor(
     overlay_label_name.set_text("Next Label: ");
     overlay_label.set_width(200);
 
+    display.set_image_clicked_handler(*this, &metadata_editor::on_image_clicked);
     display.set_overlay_rects_changed_handler(*this, &metadata_editor::on_overlay_rects_changed);
     display.set_overlay_rect_selected_handler(*this, &metadata_editor::on_overlay_rect_selected);
     overlay_label.set_text_modified_handler(*this, &metadata_editor::on_overlay_label_changed);
@@ -479,7 +459,8 @@ on_lb_images_clicked(
 // ----------------------------------------------------------------------------------------
 
 std::vector<dlib::image_display::overlay_rect> get_overlays (
-    const dlib::image_dataset_metadata::image& data
+    const dlib::image_dataset_metadata::image& data,
+    color_mapper& string_to_color 
 )
 {
     std::vector<dlib::image_display::overlay_rect> temp(data.boxes.size());
@@ -521,7 +502,7 @@ load_image(
     if (display_equialized_image)
         equalize_histogram(img);
     display.set_image(img);
-    display.add_overlay(get_overlays(metadata.images[idx]));
+    display.add_overlay(get_overlays(metadata.images[idx], string_to_color));
 }
 
 // ----------------------------------------------------------------------------------------
@@ -569,7 +550,7 @@ load_image_and_set_size(
     if (display_equialized_image)
         equalize_histogram(img);
     display.set_image(img);
-    display.add_overlay(get_overlays(metadata.images[idx]));
+    display.add_overlay(get_overlays(metadata.images[idx], string_to_color));
 }
 
 // ----------------------------------------------------------------------------------------
@@ -600,12 +581,21 @@ on_overlay_rects_changed(
 
 // ----------------------------------------------------------------------------------------
 
+void metadata_editor::
+on_image_clicked(
+    const point& /*p*/, bool /*is_double_click*/, unsigned long /*btn*/
+)
+{
+    display.set_default_overlay_rect_color(string_to_color(trim(overlay_label.text())));
+}
+
+// ----------------------------------------------------------------------------------------
+
 void metadata_editor::
 on_overlay_label_changed(
 )
 {
     display.set_default_overlay_rect_label(trim(overlay_label.text()));
-    display.set_default_overlay_rect_color(string_to_color(trim(overlay_label.text())));
 }
 
 // ----------------------------------------------------------------------------------------

tools/imglab/src/metadata_editor.h

@@ -4,7 +4,54 @@
 #define DLIB_METADATA_EdITOR_H__
 
 #include <dlib/gui_widgets.h>
-#include "dlib/data_io.h"
+#include <dlib/data_io.h>
+#include <dlib/pixel.h>
+#include <map>
+
+// ----------------------------------------------------------------------------------------
+
+class color_mapper
+{
+public:
+
+    dlib::rgb_alpha_pixel operator() (
+        const std::string& str
+    ) 
+    {
+        auto i = colors.find(str);
+        if (i != colors.end())
+        {
+            return i->second;
+        }
+        else
+        {
+            using namespace dlib;
+            hsi_pixel pix;
+            pix.h = reverse(colors.size());
+            std::cout << "new h: "<< (unsigned int)pix.h << std::endl;
+            pix.s = 255;
+            pix.i = 150;
+            rgb_alpha_pixel result;
+            assign_pixel(result, pix);
+            colors[str] = result;
+            return result;
+        }
+    }
+
+private:
+
+    // We use a bit reverse here because it causes us to evenly spread the colors as we
+    // allocated them. First the colors are maximally different, then become interleaved
+    // and progressively more similar as they are allocated.
+    unsigned char reverse(unsigned char b)
+    {
+        // reverse the order of the bits in b.
+        b = ((b * 0x0802LU & 0x22110LU) | (b * 0x8020LU & 0x88440LU)) * 0x10101LU >> 16; 
+        return b;
+    }
+
+    std::map<std::string, dlib::rgb_alpha_pixel> colors;
+};
 
 // ----------------------------------------------------------------------------------------
 
@@ -39,6 +86,7 @@ private:
     void save_metadata_to_file (const std::string& file);
     void load_image(unsigned long idx);
     void load_image_and_set_size(unsigned long idx);
+    void on_image_clicked(const dlib::point& p, bool is_double_click, unsigned long btn);
     void on_overlay_rects_changed();
     void on_overlay_label_changed();
     void on_overlay_rect_selected(const dlib::image_display::overlay_rect& orect);
@@ -59,6 +107,7 @@ private:
     unsigned long keyboard_jump_pos;
     time_t last_keyboard_jump_pos_update;
     bool display_equialized_image = false;
+    color_mapper string_to_color;
 };
 
 // ----------------------------------------------------------------------------------------