feat(pretrained): add VGG19 model and export in pretrained package

pydeepflow/pretrained/__init__.py

@@ -6,5 +6,6 @@
 """
 
 from .vgg16 import VGG16
+from .vgg19 import VGG19
 
-__all__ = ['VGG16']
+__all__ = ['VGG16', 'VGG19']

pydeepflow/pretrained/vgg19.py

@@ -0,0 +1,347 @@
+"""
+VGG19 Architecture Implementation for PyDeepFlow
+
+This module implements the VGG19 deep convolutional neural network architecture
+for transfer learning and feature extraction tasks.
+
+VGG19 Architecture:
+- Input: 224x224x3 RGB images
+- 5 convolutional blocks with max pooling
+- 3 fully connected layers (optional with include_top)
+- Total: 16 conv layers + 3 FC layers = 19 layers with learnable parameters
+
+Reference:
+Simonyan, K., & Zisserman, A. (2014). Very Deep Convolutional Networks for 
+Large-Scale Image Recognition. arXiv:1409.1556
+"""
+
+import numpy as np
+from pydeepflow.model import ConvLayer, MaxPooling2D, Flatten
+from pydeepflow.device import Device
+from pydeepflow.weight_initialization import WeightInitializer
+from pydeepflow.activations import activation
+import warnings
+
+
+class VGG19:
+    """
+    VGG19 Convolutional Neural Network for Transfer Learning.
+
+    This class implements the VGG19 architecture, which consists of:
+    - Block 1: 2 conv layers (64 filters) + max pool
+    - Block 2: 2 conv layers (128 filters) + max pool
+    - Block 3: 4 conv layers (256 filters) + max pool
+    - Block 4: 4 conv layers (512 filters) + max pool
+    - Block 5: 4 conv layers (512 filters) + max pool
+    - Flatten layer (if include_top=True)
+    - FC layer 1: 4096 neurons (if include_top=True)
+    - FC layer 2: 4096 neurons (if include_top=True)
+    - FC layer 3: num_classes neurons (output, if include_top=True)
+
+    Convolutional layers use 3x3 kernels, stride=1, padding=1, ReLU activation.
+    Max pooling layers use 2x2 window with stride=2.
+
+    Parameters
+    ----------
+    num_classes : int, optional
+        Number of output classes for classification. Default is 1000 (ImageNet).
+    input_shape : tuple, optional
+        Input image shape (height, width, channels). Default is (224, 224, 3).
+    use_gpu : bool, optional
+        Whether to use GPU acceleration. Default is False.
+    include_top : bool, optional
+        Whether to include the fully connected layers at the top. Default is True.
+        Set to False for feature extraction.
+    weights : str or None, optional
+        Path to pretrained weights file or None for random initialization.
+        Default is None.
+    freeze_features : bool, optional
+        If True, freeze convolutional layers for feature extraction mode.
+        Default is False.
+    """
+
+    def __init__(self, num_classes=1000, input_shape=(224, 224, 3),
+                 use_gpu=False, include_top=True, weights=None,
+                 freeze_features=False):
+        self.device = Device(use_gpu=use_gpu)
+        self.num_classes = num_classes
+        self.input_shape = input_shape
+        self.include_top = include_top
+        self.frozen_layers = set()
+
+        # Validate input shape
+        if len(input_shape) != 3:
+            raise ValueError(f"input_shape must be 3D (H, W, C), got {input_shape}")
+
+        if input_shape[2] != 3:
+            warnings.warn(
+                f"VGG19 was designed for RGB images (3 channels), "
+                f"but got {input_shape[2]} channels. This may affect performance."
+            )
+
+        # Build the architecture
+        self.layers = []
+        self.feature_layers = []
+        self.classifier_layers = []
+
+        self._build_architecture()
+
+        # Load pretrained weights if provided
+        if weights is not None:
+            self.load_weights(weights)
+
+        # Freeze feature layers if requested
+        if freeze_features:
+            self.freeze_feature_layers()
+
+    def _build_architecture(self):
+        """Build the complete VGG19 architecture."""
+        H, W, C = self.input_shape
+
+        # ================================
+        # BLOCK 1: 2x Conv(64) + MaxPool
+        # ================================
+        conv1_1 = ConvLayer(in_channels=C, out_channels=64, kernel_size=3,
+                            stride=1, padding=1, device=self.device,
+                            activation='relu', weight_init='he_normal')
+        self.layers.append(conv1_1); self.feature_layers.append(conv1_1)
+        conv1_2 = ConvLayer(in_channels=64, out_channels=64, kernel_size=3,
+                            stride=1, padding=1, device=self.device,
+                            activation='relu', weight_init='he_normal')
+        self.layers.append(conv1_2); self.feature_layers.append(conv1_2)
+        pool1 = MaxPooling2D(pool_size=(2, 2), stride=2)
+        self.layers.append(pool1); self.feature_layers.append(pool1)
+        H, W = H // 2, W // 2
+
+        # ================================
+        # BLOCK 2: 2x Conv(128) + MaxPool
+        # ================================
+        conv2_1 = ConvLayer(in_channels=64, out_channels=128, kernel_size=3,
+                            stride=1, padding=1, device=self.device,
+                            activation='relu', weight_init='he_normal')
+        self.layers.append(conv2_1); self.feature_layers.append(conv2_1)
+        conv2_2 = ConvLayer(in_channels=128, out_channels=128, kernel_size=3,
+                            stride=1, padding=1, device=self.device,
+                            activation='relu', weight_init='he_normal')
+        self.layers.append(conv2_2); self.feature_layers.append(conv2_2)
+        pool2 = MaxPooling2D(pool_size=(2, 2), stride=2)
+        self.layers.append(pool2); self.feature_layers.append(pool2)
+        H, W = H // 2, W // 2
+
+        # ================================
+        # BLOCK 3: 4x Conv(256) + MaxPool
+        # ================================
+        in_c = 128
+        for _ in range(4):
+            conv = ConvLayer(in_channels=in_c, out_channels=256, kernel_size=3,
+                             stride=1, padding=1, device=self.device,
+                             activation='relu', weight_init='he_normal')
+            self.layers.append(conv); self.feature_layers.append(conv)
+            in_c = 256
+        pool3 = MaxPooling2D(pool_size=(2, 2), stride=2)
+        self.layers.append(pool3); self.feature_layers.append(pool3)
+        H, W = H // 2, W // 2
+
+        # ================================
+        # BLOCK 4: 4x Conv(512) + MaxPool
+        # ================================
+        in_c = 256
+        for _ in range(4):
+            conv = ConvLayer(in_channels=in_c, out_channels=512, kernel_size=3,
+                             stride=1, padding=1, device=self.device,
+                             activation='relu', weight_init='he_normal')
+            self.layers.append(conv); self.feature_layers.append(conv)
+            in_c = 512
+        pool4 = MaxPooling2D(pool_size=(2, 2), stride=2)
+        self.layers.append(pool4); self.feature_layers.append(pool4)
+        H, W = H // 2, W // 2
+
+        # ================================
+        # BLOCK 5: 4x Conv(512) + MaxPool
+        # ================================
+        in_c = 512
+        for _ in range(4):
+            conv = ConvLayer(in_channels=in_c, out_channels=512, kernel_size=3,
+                             stride=1, padding=1, device=self.device,
+                             activation='relu', weight_init='he_normal')
+            self.layers.append(conv); self.feature_layers.append(conv)
+            in_c = 512
+        pool5 = MaxPooling2D(pool_size=(2, 2), stride=2)
+        self.layers.append(pool5); self.feature_layers.append(pool5)
+        H, W = H // 2, W // 2
+
+        # ================================
+        # FULLY CONNECTED (Classifier)
+        # ================================
+        if self.include_top:
+            flatten = Flatten(); self.layers.append(flatten)
+            flattened_size = H * W * 512
+            initializer = WeightInitializer(device=self.device, mode='auto', bias_init='auto')
+
+            fc1_w, fc1_b, _ = initializer.initialize_dense_layer(
+                input_dim=flattened_size, output_dim=4096, activation='relu')
+            fc1 = {
+                'W': self.device.array(fc1_w),
+                'b': self.device.array(fc1_b.reshape(1, -1)),
+                'activation': 'relu'
+            }
+            self.layers.append(fc1); self.classifier_layers.append(fc1)
+
+            fc2_w, fc2_b, _ = initializer.initialize_dense_layer(
+                input_dim=4096, output_dim=4096, activation='relu')
+            fc2 = {
+                'W': self.device.array(fc2_w),
+                'b': self.device.array(fc2_b.reshape(1, -1)),
+                'activation': 'relu'
+            }
+            self.layers.append(fc2); self.classifier_layers.append(fc2)
+
+            output_activation = 'softmax' if self.num_classes > 1 else 'sigmoid'
+            fc3_w, fc3_b, _ = initializer.initialize_dense_layer(
+                input_dim=4096, output_dim=self.num_classes, activation=output_activation)
+            fc3 = {
+                'W': self.device.array(fc3_w),
+                'b': self.device.array(fc3_b.reshape(1, -1)),
+                'activation': output_activation
+            }
+            self.layers.append(fc3); self.classifier_layers.append(fc3)
+
+    def forward(self, X, training=False):
+        """Forward pass through the network."""
+        if X.ndim != 4:
+            raise ValueError(f"Input must be 4D (N, H, W, C), got shape {X.shape}")
+        if X.shape[1:] != self.input_shape:
+            warnings.warn(
+                f"Input shape {X.shape[1:]} differs from expected {self.input_shape}. This may affect performance."
+            )
+        current_output = X
+        for layer in self.layers:
+            if isinstance(layer, (ConvLayer, MaxPooling2D, Flatten)):
+                current_output = layer.forward(current_output)
+            elif isinstance(layer, dict) and 'W' in layer:
+                Z = self.device.dot(current_output, layer['W']) + layer['b']
+                current_output = activation(Z, layer['activation'], self.device)
+        return current_output
+
+    def predict(self, X):
+        """Make predictions on input data (inference mode)."""
+        return self.forward(X, training=False)
+
+    def freeze_feature_layers(self):
+        """Freeze all convolutional layers for feature extraction."""
+        for i, layer in enumerate(self.layers):
+            if isinstance(layer, ConvLayer):
+                self.frozen_layers.add(i)
+        print(f"Frozen {len(self.frozen_layers)} convolutional layers for feature extraction.")
+
+    def unfreeze_layers(self, layer_names=None, num_layers=None):
+        """Unfreeze specific layers or the last N conv layers for fine-tuning."""
+        if layer_names is not None:
+            for idx in layer_names:
+                if idx in self.frozen_layers:
+                    self.frozen_layers.remove(idx)
+            print(f"Unfrozen layers: {layer_names}")
+        elif num_layers is not None:
+            conv_indices = [i for i, layer in enumerate(self.layers) if isinstance(layer, ConvLayer)]
+            to_unfreeze = conv_indices[-num_layers:] if num_layers <= len(conv_indices) else conv_indices
+            for idx in to_unfreeze:
+                if idx in self.frozen_layers:
+                    self.frozen_layers.remove(idx)
+            print(f"Unfrozen last {len(to_unfreeze)} convolutional layers.")
+        else:
+            self.frozen_layers.clear()
+            print("Unfrozen all layers.")
+
+    def get_trainable_params(self):
+        """Return list of all trainable parameter arrays (not frozen)."""
+        trainable = []
+        for i, layer in enumerate(self.layers):
+            if i not in self.frozen_layers:
+                if isinstance(layer, ConvLayer):
+                    trainable.extend([layer.params['W'], layer.params['b']])
+                elif isinstance(layer, dict) and 'W' in layer:
+                    trainable.extend([layer['W'], layer['b']])
+        return trainable
+
+    def summary(self):
+        """Print a summary of the VGG19 architecture."""
+        print("=" * 80)
+        print("VGG19 Architecture Summary")
+        print("=" * 80)
+        print(f"Input Shape: {self.input_shape}")
+        print(f"Number of Classes: {self.num_classes}")
+        print(f"Include Top (FC Layers): {self.include_top}")
+        print(f"Frozen Layers: {len(self.frozen_layers)}")
+        print("=" * 80)
+        print(f"{'Layer':<30} {'Output Shape':<25} {'Params':<15}")
+        print("-" * 80)
+
+        H, W, C = self.input_shape
+        total_params = 0
+        for i, layer in enumerate(self.layers):
+            frozen_mark = " [FROZEN]" if i in self.frozen_layers else ""
+            if isinstance(layer, ConvLayer):
+                out_c = layer.out_channels
+                params = (layer.Fh * layer.Fw * layer.in_channels * out_c) + out_c
+                output_shape = f"({H}, {W}, {out_c})"
+                layer_name = f"Conv2D_{i}{frozen_mark}"
+                print(f"{layer_name:<30} {output_shape:<25} {params:<15,}")
+                total_params += params
+                C = out_c
+            elif isinstance(layer, MaxPooling2D):
+                H, W = H // layer.stride, W // layer.stride
+                output_shape = f"({H}, {W}, {C})"
+                layer_name = f"MaxPooling2D_{i}"
+                print(f"{layer_name:<30} {output_shape:<25} {'0':<15}")
+            elif isinstance(layer, Flatten):
+                flat_size = H * W * C
+                output_shape = f"({flat_size},)"
+                layer_name = "Flatten"
+                print(f"{layer_name:<30} {output_shape:<25} {'0':<15}")
+            elif isinstance(layer, dict) and 'W' in layer:
+                in_size = layer['W'].shape[0]
+                out_size = layer['W'].shape[1]
+                params = (in_size * out_size) + out_size
+                output_shape = f"({out_size},)"
+                layer_name = f"Dense_{i}{frozen_mark}"
+                print(f"{layer_name:<30} {output_shape:<25} {params:<15,}")
+                total_params += params
+
+        print("=" * 80)
+        print(f"Total Parameters: {total_params:,}")
+        trainable_params = sum(np.prod(p.shape) for p in self.get_trainable_params())
+        print(f"Trainable Parameters: {trainable_params:,}")
+        print(f"Non-trainable Parameters: {total_params - trainable_params:,}")
+        print("=" * 80)
+
+    def save_weights(self, filepath):
+        """Save model weights to a .npy file."""
+        weights_dict = {}
+        for i, layer in enumerate(self.layers):
+            if isinstance(layer, ConvLayer):
+                weights_dict[f'conv_{i}_W'] = self.device.asnumpy(layer.params['W'])
+                weights_dict[f'conv_{i}_b'] = self.device.asnumpy(layer.params['b'])
+            elif isinstance(layer, dict) and 'W' in layer:
+                weights_dict[f'dense_{i}_W'] = self.device.asnumpy(layer['W'])
+                weights_dict[f'dense_{i}_b'] = self.device.asnumpy(layer['b'])
+        np.save(filepath, weights_dict)
+        print(f"Model weights saved to {filepath}")
+
+    def load_weights(self, filepath):
+        """Load model weights from a .npy file."""
+        try:
+            weights_dict = np.load(filepath, allow_pickle=True).item()
+            for i, layer in enumerate(self.layers):
+                if isinstance(layer, ConvLayer):
+                    if f'conv_{i}_W' in weights_dict:
+                        layer.params['W'] = self.device.array(weights_dict[f'conv_{i}_W'])
+                        layer.params['b'] = self.device.array(weights_dict[f'conv_{i}_b'])
+                elif isinstance(layer, dict) and 'W' in layer:
+                    if f'dense_{i}_W' in weights_dict:
+                        layer['W'] = self.device.array(weights_dict[f'dense_{i}_W'])
+                        layer['b'] = self.device.array(weights_dict[f'dense_{i}_b'])
+            print(f"Model weights loaded from {filepath}")
+        except FileNotFoundError:
+            raise FileNotFoundError(f"Weights file not found: {filepath}")
+        except Exception as e:
+            raise RuntimeError(f"Error loading weights: {str(e)}")