From 3a33d00d22ef55247fe379b8e6c53850f43a32a8 Mon Sep 17 00:00:00 2001
From: Alexey <AlexeyAB@users.noreply.github.com>
Date: Tue, 19 Jun 2018 22:29:59 +0000
Subject: [PATCH] Update Readme.md

---
 src/yolo_layer.c |  103 ++++++++++++++++++++++++++++++++++++++++-----------
 1 files changed, 81 insertions(+), 22 deletions(-)

diff --git a/src/yolo_layer.c b/src/yolo_layer.c
index 46846ef..f79bc41 100644
--- a/src/yolo_layer.c
+++ b/src/yolo_layer.c
@@ -10,7 +10,7 @@
 #include <string.h>
 #include <stdlib.h>
 
-layer make_yolo_layer(int batch, int w, int h, int n, int total, int *mask, int classes)
+layer make_yolo_layer(int batch, int w, int h, int n, int total, int *mask, int classes, int max_boxes)
 {
     int i;
     layer l = {0};
@@ -38,7 +38,8 @@
     l.bias_updates = calloc(n*2, sizeof(float));
     l.outputs = h*w*n*(classes + 4 + 1);
     l.inputs = l.outputs;
-    l.truths = 90*(4 + 1);
+	l.max_boxes = max_boxes;
+    l.truths = l.max_boxes*(4 + 1);	// 90*(4 + 1);
     l.delta = calloc(batch*l.outputs, sizeof(float));
     l.output = calloc(batch*l.outputs, sizeof(float));
     for(i = 0; i < total*2; ++i){
@@ -54,7 +55,7 @@
     l.delta_gpu = cuda_make_array(l.delta, batch*l.outputs);
 #endif
 
-    fprintf(stderr, "detection\n");
+    fprintf(stderr, "yolo\n");
     srand(0);
 
     return l;
@@ -108,18 +109,41 @@
 }
 
 
-void delta_yolo_class(float *output, float *delta, int index, int class, int classes, int stride, float *avg_cat)
+void delta_yolo_class(float *output, float *delta, int index, int class_id, int classes, int stride, float *avg_cat, int focal_loss)
 {
     int n;
-    if (delta[index]){
-        delta[index + stride*class] = 1 - output[index + stride*class];
-        if(avg_cat) *avg_cat += output[index + stride*class];
+    if (delta[index + stride*class_id]){
+        delta[index + stride*class_id] = 1 - output[index + stride*class_id];
+        if(avg_cat) *avg_cat += output[index + stride*class_id];
         return;
     }
-    for(n = 0; n < classes; ++n){
-        delta[index + stride*n] = ((n == class)?1 : 0) - output[index + stride*n];
-        if(n == class && avg_cat) *avg_cat += output[index + stride*n];
-    }
+	// Focal loss
+	if (focal_loss) {
+		// Focal Loss
+		float alpha = 0.5;	// 0.25 or 0.5
+		//float gamma = 2;	// hardcoded in many places of the grad-formula	
+
+		int ti = index + stride*class_id;
+		float pt = output[ti] + 0.000000000000001F;
+		// http://fooplot.com/#W3sidHlwZSI6MCwiZXEiOiItKDEteCkqKDIqeCpsb2coeCkreC0xKSIsImNvbG9yIjoiIzAwMDAwMCJ9LHsidHlwZSI6MTAwMH1d
+		float grad = -(1 - pt) * (2 * pt*logf(pt) + pt - 1);	// http://blog.csdn.net/linmingan/article/details/77885832	
+		//float grad = (1 - pt) * (2 * pt*logf(pt) + pt - 1);	// https://github.com/unsky/focal-loss
+
+		for (n = 0; n < classes; ++n) {
+			delta[index + stride*n] = (((n == class_id) ? 1 : 0) - output[index + stride*n]);
+
+			delta[index + stride*n] *= alpha*grad;
+
+			if (n == class_id) *avg_cat += output[index + stride*n];
+		}
+	}
+	else {
+		// default
+		for (n = 0; n < classes; ++n) {
+			delta[index + stride*n] = ((n == class_id) ? 1 : 0) - output[index + stride*n];
+			if (n == class_id && avg_cat) *avg_cat += output[index + stride*n];
+		}
+	}
 }
 
 static int entry_index(layer l, int batch, int location, int entry)
@@ -129,6 +153,16 @@
     return batch*l.outputs + n*l.w*l.h*(4+l.classes+1) + entry*l.w*l.h + loc;
 }
 
+static box float_to_box_stride(float *f, int stride)
+{
+	box b = { 0 };
+	b.x = f[0];
+	b.y = f[1 * stride];
+	b.w = f[2 * stride];
+	b.h = f[3 * stride];
+	return b;
+}
+
 void forward_yolo_layer(const layer l, network_state state)
 {
     int i,j,b,t,n;
@@ -165,7 +199,13 @@
                     float best_iou = 0;
                     int best_t = 0;
                     for(t = 0; t < l.max_boxes; ++t){
-                        box truth = float_to_box(state.truth + t*(4 + 1) + b*l.truths, 1);
+                        box truth = float_to_box_stride(state.truth + t*(4 + 1) + b*l.truths, 1);
+						int class_id = state.truth[t*(4 + 1) + b*l.truths + 4];
+						if (class_id >= l.classes) {
+							printf(" Warning: in txt-labels class_id=%d >= classes=%d in cfg-file. In txt-labels class_id should be [from 0 to %d] \n", class_id, l.classes, l.classes - 1);
+							getchar();
+							continue; // if label contains class_id more than number of classes in the cfg-file
+						}
                         if(!truth.x) break;
                         float iou = box_iou(pred, truth);
                         if (iou > best_iou) {
@@ -182,18 +222,20 @@
                     if (best_iou > l.truth_thresh) {
                         l.delta[obj_index] = 1 - l.output[obj_index];
 
-                        int class = state.truth[best_t*(4 + 1) + b*l.truths + 4];
-                        if (l.map) class = l.map[class];
+                        int class_id = state.truth[best_t*(4 + 1) + b*l.truths + 4];
+                        if (l.map) class_id = l.map[class_id];
                         int class_index = entry_index(l, b, n*l.w*l.h + j*l.w + i, 4 + 1);
-                        delta_yolo_class(l.output, l.delta, class_index, class, l.classes, l.w*l.h, 0);
-                        box truth = float_to_box(state.truth + best_t*(4 + 1) + b*l.truths, 1);
+                        delta_yolo_class(l.output, l.delta, class_index, class_id, l.classes, l.w*l.h, 0, l.focal_loss);
+                        box truth = float_to_box_stride(state.truth + best_t*(4 + 1) + b*l.truths, 1);
                         delta_yolo_box(truth, l.output, l.biases, l.mask[n], box_index, i, j, l.w, l.h, state.net.w, state.net.h, l.delta, (2-truth.w*truth.h), l.w*l.h);
                     }
                 }
             }
         }
         for(t = 0; t < l.max_boxes; ++t){
-            box truth = float_to_box(state.truth + t*(4 + 1) + b*l.truths, 1);
+            box truth = float_to_box_stride(state.truth + t*(4 + 1) + b*l.truths, 1);
+			int class_id = state.truth[t*(4 + 1) + b*l.truths + 4];
+			if (class_id >= l.classes) continue; // if label contains class_id more than number of classes in the cfg-file
 
             if(!truth.x) break;
             float best_iou = 0;
@@ -222,10 +264,10 @@
                 avg_obj += l.output[obj_index];
                 l.delta[obj_index] = 1 - l.output[obj_index];
 
-                int class = state.truth[t*(4 + 1) + b*l.truths + 4];
-                if (l.map) class = l.map[class];
+                int class_id = state.truth[t*(4 + 1) + b*l.truths + 4];
+                if (l.map) class_id = l.map[class_id];
                 int class_index = entry_index(l, b, mask_n*l.w*l.h + j*l.w + i, 4 + 1);
-                delta_yolo_class(l.output, l.delta, class_index, class, l.classes, l.w*l.h, &avg_cat);
+                delta_yolo_class(l.output, l.delta, class_index, class_id, l.classes, l.w*l.h, &avg_cat, l.focal_loss);
 
                 ++count;
                 ++class_count;
@@ -368,9 +410,26 @@
         return;
     }
 
-    cuda_pull_array(l.output_gpu, state.input, l.batch*l.inputs);
-    forward_yolo_layer(l, state);
+    //cuda_pull_array(l.output_gpu, state.input, l.batch*l.inputs);
+	float *in_cpu = calloc(l.batch*l.inputs, sizeof(float));
+	cuda_pull_array(l.output_gpu, in_cpu, l.batch*l.inputs);
+	float *truth_cpu = 0;
+	if (state.truth) {
+		int num_truth = l.batch*l.truths;
+		truth_cpu = calloc(num_truth, sizeof(float));
+		cuda_pull_array(state.truth, truth_cpu, num_truth);
+	}
+	network_state cpu_state = state;
+	cpu_state.net = state.net;
+	cpu_state.index = state.index;
+	cpu_state.train = state.train;
+	cpu_state.truth = truth_cpu;
+	cpu_state.input = in_cpu;
+	forward_yolo_layer(l, cpu_state);
+    //forward_yolo_layer(l, state);
     cuda_push_array(l.delta_gpu, l.delta, l.batch*l.outputs);
+	free(in_cpu);
+	if (cpu_state.truth) free(cpu_state.truth);
 }
 
 void backward_yolo_layer_gpu(const layer l, network_state state)

--
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