From b715671988a4f3e476586df52fa3bf052cce7f80 Mon Sep 17 00:00:00 2001
From: Joseph Redmon <pjreddie@gmail.com>
Date: Thu, 05 Dec 2013 21:17:16 +0000
Subject: [PATCH] Works well on MNIST

---
 src/convolutional_layer.c |  172 +++++++++++++++++++++++++++++++++++++++++++--------------
 1 files changed, 130 insertions(+), 42 deletions(-)

diff --git a/src/convolutional_layer.c b/src/convolutional_layer.c
index d4aff73..45b55b8 100644
--- a/src/convolutional_layer.c
+++ b/src/convolutional_layer.c
@@ -1,55 +1,74 @@
 #include "convolutional_layer.h"
+#include "utils.h"
 #include <stdio.h>
 
 image get_convolutional_image(convolutional_layer layer)
 {
-    int h = (layer.h-1)/layer.stride + 1;
-    int w = (layer.w-1)/layer.stride + 1;
-    int c = layer.n;
+    int h,w,c;
+    if(layer.edge){
+        h = (layer.h-1)/layer.stride + 1;
+        w = (layer.w-1)/layer.stride + 1;
+    }else{
+        h = (layer.h - layer.size)/layer.stride+1;
+        w = (layer.h - layer.size)/layer.stride+1;
+    }
+    c = layer.n;
     return double_to_image(h,w,c,layer.output);
 }
 
 image get_convolutional_delta(convolutional_layer layer)
 {
-    int h = (layer.h-1)/layer.stride + 1;
-    int w = (layer.w-1)/layer.stride + 1;
-    int c = layer.n;
+    int h,w,c;
+    if(layer.edge){
+        h = (layer.h-1)/layer.stride + 1;
+        w = (layer.w-1)/layer.stride + 1;
+    }else{
+        h = (layer.h - layer.size)/layer.stride+1;
+        w = (layer.h - layer.size)/layer.stride+1;
+    }
+    c = layer.n;
     return double_to_image(h,w,c,layer.delta);
 }
 
-convolutional_layer *make_convolutional_layer(int h, int w, int c, int n, int size, int stride, ACTIVATION activator)
+convolutional_layer *make_convolutional_layer(int h, int w, int c, int n, int size, int stride, ACTIVATION activation)
 {
-    printf("Convolutional Layer: %d x %d x %d image, %d filters\n", h,w,c,n);
     int i;
+    int out_h,out_w;
     convolutional_layer *layer = calloc(1, sizeof(convolutional_layer));
     layer->h = h;
     layer->w = w;
     layer->c = c;
     layer->n = n;
+    layer->edge = 1;
     layer->stride = stride;
     layer->kernels = calloc(n, sizeof(image));
     layer->kernel_updates = calloc(n, sizeof(image));
+    layer->kernel_momentum = calloc(n, sizeof(image));
     layer->biases = calloc(n, sizeof(double));
     layer->bias_updates = calloc(n, sizeof(double));
+    layer->bias_momentum = calloc(n, sizeof(double));
+    double scale = 2./(size*size);
     for(i = 0; i < n; ++i){
-        layer->biases[i] = .005;
-        layer->kernels[i] = make_random_kernel(size, c);
-        layer->kernel_updates[i] = make_random_kernel(size, c);
+        //layer->biases[i] = rand_normal()*scale + scale;
+        layer->biases[i] = 0;
+        layer->kernels[i] = make_random_kernel(size, c, scale);
+        layer->kernel_updates[i] = make_random_kernel(size, c, 0);
+        layer->kernel_momentum[i] = make_random_kernel(size, c, 0);
     }
-    layer->output = calloc(((h-1)/stride+1) * ((w-1)/stride+1) * n, sizeof(double));
-    layer->delta  = calloc(((h-1)/stride+1) * ((w-1)/stride+1) * n, sizeof(double));
+    layer->size = 2*(size/2)+1;
+    if(layer->edge){
+        out_h = (layer->h-1)/layer->stride + 1;
+        out_w = (layer->w-1)/layer->stride + 1;
+    }else{
+        out_h = (layer->h - layer->size)/layer->stride+1;
+        out_w = (layer->h - layer->size)/layer->stride+1;
+    }
+    fprintf(stderr, "Convolutional Layer: %d x %d x %d image, %d filters -> %d x %d x %d image\n", h,w,c,n, out_h, out_w, n);
+    layer->output = calloc(out_h * out_w * n, sizeof(double));
+    layer->delta  = calloc(out_h * out_w * n, sizeof(double));
     layer->upsampled = make_image(h,w,n);
+    layer->activation = activation;
 
-    if(activator == SIGMOID){
-        layer->activation = sigmoid_activation;
-        layer->gradient = sigmoid_gradient;
-    }else if(activator == RELU){
-        layer->activation = relu_activation;
-        layer->gradient = relu_gradient;
-    }else if(activator == IDENTITY){
-        layer->activation = identity_activation;
-        layer->gradient = identity_gradient;
-    }
     return layer;
 }
 
@@ -59,13 +78,13 @@
     image output = get_convolutional_image(layer);
     int i,j;
     for(i = 0; i < layer.n; ++i){
-        convolve(input, layer.kernels[i], layer.stride, i, output);
+        convolve(input, layer.kernels[i], layer.stride, i, output, layer.edge);
     }
     for(i = 0; i < output.c; ++i){
         for(j = 0; j < output.h*output.w; ++j){
             int index = i*output.h*output.w + j;
             output.data[index] += layer.biases[i];
-            output.data[index] = layer.activation(output.data[index]);
+            output.data[index] = activate(output.data[index], layer.activation);
         }
     }
 }
@@ -74,32 +93,29 @@
 {
     int i;
 
-    image in_image = double_to_image(layer.h, layer.w, layer.c, input);
     image in_delta = double_to_image(layer.h, layer.w, layer.c, delta);
     image out_delta = get_convolutional_delta(layer);
     zero_image(in_delta);
 
     for(i = 0; i < layer.n; ++i){
-        back_convolve(in_delta, layer.kernels[i], layer.stride, i, out_delta);
-    }
-    for(i = 0; i < layer.h*layer.w*layer.c; ++i){
-        in_delta.data[i] *= layer.gradient(in_image.data[i]);
+        back_convolve(in_delta, layer.kernels[i], layer.stride, i, out_delta, layer.edge);
     }
 }
 
-/*
-void backpropagate_convolutional_layer_convolve(image input, convolutional_layer layer)
+void backward_convolutional_layer2(convolutional_layer layer, double *input, double *delta)
 {
+    image in_delta = double_to_image(layer.h, layer.w, layer.c, delta);
+    image out_delta = get_convolutional_delta(layer);
     int i,j;
     for(i = 0; i < layer.n; ++i){
         rotate_image(layer.kernels[i]);
     }
 
-    zero_image(input);
-    upsample_image(layer.output, layer.stride, layer.upsampled);
-    for(j = 0; j < input.c; ++j){
+    zero_image(in_delta);
+    upsample_image(out_delta, layer.stride, layer.upsampled);
+    for(j = 0; j < in_delta.c; ++j){
         for(i = 0; i < layer.n; ++i){
-            two_d_convolve(layer.upsampled, i, layer.kernels[i], j, 1, input, j);
+            two_d_convolve(layer.upsampled, i, layer.kernels[i], j, 1, in_delta, j, layer.edge);
         }
     }
 
@@ -107,34 +123,106 @@
         rotate_image(layer.kernels[i]);
     }
 }
-*/
+
+void gradient_delta_convolutional_layer(convolutional_layer layer)
+{
+    int i;
+    image out_delta = get_convolutional_delta(layer);
+    image out_image = get_convolutional_image(layer);
+    for(i = 0; i < out_image.h*out_image.w*out_image.c; ++i){
+        out_delta.data[i] *= gradient(out_image.data[i], layer.activation);
+    }
+}
 
 void learn_convolutional_layer(convolutional_layer layer, double *input)
 {
     int i;
     image in_image = double_to_image(layer.h, layer.w, layer.c, input);
     image out_delta = get_convolutional_delta(layer);
+    gradient_delta_convolutional_layer(layer);
     for(i = 0; i < layer.n; ++i){
-        kernel_update(in_image, layer.kernel_updates[i], layer.stride, i, out_delta);
+        kernel_update(in_image, layer.kernel_updates[i], layer.stride, i, out_delta, layer.edge);
         layer.bias_updates[i] += avg_image_layer(out_delta, i);
+        //printf("%30.20lf\n", layer.bias_updates[i]);
     }
 }
 
-void update_convolutional_layer(convolutional_layer layer, double step)
+void update_convolutional_layer(convolutional_layer layer, double step, double momentum, double decay)
 {
-    return;
+    //step = .01;
     int i,j;
     for(i = 0; i < layer.n; ++i){
-        layer.biases[i] += step*layer.bias_updates[i];
+        layer.bias_momentum[i] = step*(layer.bias_updates[i]) 
+                                + momentum*layer.bias_momentum[i];
+        layer.biases[i] += layer.bias_momentum[i];
+        //layer.biases[i] = constrain(layer.biases[i],1.);
         layer.bias_updates[i] = 0;
         int pixels = layer.kernels[i].h*layer.kernels[i].w*layer.kernels[i].c;
         for(j = 0; j < pixels; ++j){
-            layer.kernels[i].data[j] += step*layer.kernel_updates[i].data[j];
+            layer.kernel_momentum[i].data[j] = step*(layer.kernel_updates[i].data[j] - decay*layer.kernels[i].data[j]) 
+                                                + momentum*layer.kernel_momentum[i].data[j];
+            layer.kernels[i].data[j] += layer.kernel_momentum[i].data[j];
+            //layer.kernels[i].data[j] = constrain(layer.kernels[i].data[j], 1.);
         }
         zero_image(layer.kernel_updates[i]);
     }
 }
 
+void visualize_convolutional_filters(convolutional_layer layer, char *window)
+{
+    int color = 1;
+    int border = 1;
+    int h,w,c;
+    int size = layer.size;
+    h = size;
+    w = (size + border) * layer.n - border;
+    c = layer.kernels[0].c;
+    if(c != 3 || !color){
+        h = (h+border)*c - border;
+        c = 1;
+    }
+
+    image filters = make_image(h,w,c);
+    int i,j;
+    for(i = 0; i < layer.n; ++i){
+        int w_offset = i*(size+border);
+        image k = layer.kernels[i];
+        image copy = copy_image(k);
+        /*
+        printf("Kernel %d - Bias: %f, Channels:",i,layer.biases[i]);
+        for(j = 0; j < k.c; ++j){
+            double a = avg_image_layer(k, j);
+            printf("%f, ", a);
+        }
+        printf("\n");
+        */
+        normalize_image(copy);
+        for(j = 0; j < k.c; ++j){
+            set_pixel(copy,0,0,j,layer.biases[i]);
+        }
+        if(c == 3 && color){
+            embed_image(copy, filters, 0, w_offset);
+        }
+        else{
+            for(j = 0; j < k.c; ++j){
+                int h_offset = j*(size+border);
+                image layer = get_image_layer(k, j);
+                embed_image(layer, filters, h_offset, w_offset);
+                free_image(layer);
+            }
+        }
+        free_image(copy);
+    }
+    image delta = get_convolutional_delta(layer);
+    image dc = collapse_image_layers(delta, 1);
+    char buff[256];
+    sprintf(buff, "%s: Delta", window);
+    show_image(dc, buff);
+    free_image(dc);
+    show_image(filters, window);
+    free_image(filters);
+}
+
 void visualize_convolutional_layer(convolutional_layer layer)
 {
     int i;

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