Added mosaic=1 data augmentation for Classifier

build/darknet/x64/cfg/efficientnet_b0.cfg

@@ -11,8 +11,9 @@ channels=3
 momentum=0.9
 decay=0.0005
 max_crop=256
-#mixup=1
+#mixup=4
 cutmix=1
+mosaic=1
 
 burn_in=1000
 #burn_in=100

cfg/efficientnet_b0.cfg

@@ -11,8 +11,9 @@ channels=3
 momentum=0.9
 decay=0.0005
 max_crop=256
-#mixup=1
+#mixup=4
 cutmix=1
+mosaic=1
 
 burn_in=1000
 #burn_in=100

src/data.c

@@ -1323,7 +1323,6 @@ data load_data_augment(char **paths, int n, int m, char **labels, int k, tree *h
     d.shallow = 0;
     d.X = load_image_augment_paths(paths, n, use_flip, min, max, w, h, angle, aspect, hue, saturation, exposure);
     d.y = load_labels_paths(paths, n, labels, k, hierarchy);
-    if(m) free(paths);
 
     if (mixup && rand_int(0, 1)) {
         char **paths_mix = get_random_paths(paths_stored, n, m);
@@ -1331,14 +1330,32 @@ data load_data_augment(char **paths, int n, int m, char **labels, int k, tree *h
         d2.shallow = 0;
         d2.X = load_image_augment_paths(paths_mix, n, use_flip, min, max, w, h, angle, aspect, hue, saturation, exposure);
         d2.y = load_labels_paths(paths_mix, n, labels, k, hierarchy);
+        free(paths_mix);
+
+        data d3 = { 0 };
+        d3.shallow = 0;
+        data d4 = { 0 };
+        d4.shallow = 0;
+        if (mixup >= 3) {
+            char **paths_mix3 = get_random_paths(paths_stored, n, m);
+            d3.X = load_image_augment_paths(paths_mix3, n, use_flip, min, max, w, h, angle, aspect, hue, saturation, exposure);
+            d3.y = load_labels_paths(paths_mix3, n, labels, k, hierarchy);
+            free(paths_mix3);
+
+            char **paths_mix4 = get_random_paths(paths_stored, n, m);
+            d4.X = load_image_augment_paths(paths_mix4, n, use_flip, min, max, w, h, angle, aspect, hue, saturation, exposure);
+            d4.y = load_labels_paths(paths_mix4, n, labels, k, hierarchy);
+            free(paths_mix4);
+        }
+
 
         // mix
         int i, j;
         for (i = 0; i < d2.X.rows; ++i) {
 
-            if (mixup == 3) mixup = rand_int(1, 2); // alternate MixUp and CutMix
+            if (mixup == 4) mixup = rand_int(2, 3); // alternate MixUp and CutMix
 
-            // MixUp
+            // MixUp -----------------------------------
             if (mixup == 1) {
                 // mix images
                 for (j = 0; j < d2.X.cols; ++j) {
@@ -1350,8 +1367,8 @@ data load_data_augment(char **paths, int n, int m, char **labels, int k, tree *h
                     d.y.vals[i][j] = (d.y.vals[i][j] + d2.y.vals[i][j]) / 2.0f;
                 }
             }
-            // CutMix
+            // CutMix -----------------------------------
-            else {
+            else if (mixup == 2) {
                 const float min = 0.3;  // 0.3*0.3 = 9%
                 const float max = 0.8;  // 0.8*0.8 = 64%
                 const int cut_w = rand_int(w*min, w*max);
@@ -1382,10 +1399,43 @@ data load_data_augment(char **paths, int n, int m, char **labels, int k, tree *h
                     d.y.vals[i][j] = d.y.vals[i][j] * beta + d2.y.vals[i][j] * alpha;
                 }
             }
+            // Mosaic -----------------------------------
+            else if (mixup == 3)
+            {
+                const float min_offset = 0.2; // 20%
+                const int cut_x = rand_int(w*min_offset, w*(1 - min_offset));
+                const int cut_y = rand_int(h*min_offset, h*(1 - min_offset));
+
+                float s1 = (float)(cut_x * cut_y) / (w*h);
+                float s2 = (float)((w - cut_x) * cut_y) / (w*h);
+                float s3 = (float)(cut_x * (h - cut_y)) / (w*h);
+                float s4 = (float)((w - cut_x) * (h - cut_y)) / (w*h);
+
+                int c, x, y;
+                for (c = 0; c < 3; ++c) {
+                    for (y = 0; y < h; ++y) {
+                        for (x = 0; x < w; ++x) {
+                            int j = x + y*w + c*w*h;
+                            if (x < cut_x && y < cut_y) d.X.vals[i][j] = d.X.vals[i][j];
+                            if (x >= cut_x && y < cut_y) d.X.vals[i][j] = d2.X.vals[i][j];
+                            if (x < cut_x && y >= cut_y) d.X.vals[i][j] = d3.X.vals[i][j];
+                            if (x >= cut_x && y >= cut_y) d.X.vals[i][j] = d4.X.vals[i][j];
+                        }
+                    }
+                }
+
+                for (j = 0; j < d.y.cols; ++j) {
+                    d.y.vals[i][j] = d.y.vals[i][j] * s1 + d2.y.vals[i][j] * s2 + d3.y.vals[i][j] * s3 + d4.y.vals[i][j] * s4;
+                }
+            }
         }
 
         free_data(d2);
-        free(paths_mix);
+
+        if (mixup == 3) {
+            free_data(d3);
+            free_data(d4);
+        }
     }
 
     if (show_imgs) {
@@ -1416,6 +1466,8 @@ data load_data_augment(char **paths, int n, int m, char **labels, int k, tree *h
         printf("\nYou use flag -show_imgs, so will be saved aug_...jpg images. Click on window and press ESC button \n");
     }
 
+    if (m) free(paths);
+
     return d;
 }
 

src/parser.c

@@ -923,8 +923,10 @@ void parse_net_options(list *options, network *net)
     net->blur = option_find_int_quiet(options, "blur", 0);
     net->mixup = option_find_int_quiet(options, "mixup", 0);
     int cutmix = option_find_int_quiet(options, "cutmix", 0);
-    if (net->mixup && cutmix) net->mixup = 3;
+    int mosaic = option_find_int_quiet(options, "mosaic", 0);
+    if (mosaic && cutmix) net->mixup = 4;
     else if (cutmix) net->mixup = 2;
+    else if (mosaic) net->mixup = 3;
     net->letter_box = option_find_int_quiet(options, "letter_box", 0);
 
     net->angle = option_find_float_quiet(options, "angle", 0);