Computer Vision

コンピュータービジョン

概要

コンピュータービジョンにより、機械は画像や動画から視覚情報を理解できるようになります。自動運転、医療画像処理、監視などのアプリケーションを支えています。

使用する場面

• 画像分類や物体認識のタスク
• 画像内の物体検出と位置特定
• セマンティックセグメンテーションやインスタンスセグメンテーションのプロジェクト
• 姿勢推定や人間の活動認識
• 顔認識や生体認証システム
• 医療画像の解析と診断

コンピュータービジョンのタスク

• 画像分類：画像をクラスに分類します
• 物体検出：画像内の物体の位置を特定し、分類します
• セマンティックセグメンテーション：ピクセルレベルで分類します
• インスタンスセグメンテーション：個々の物体インスタンスを検出します
• 姿勢推定：人体の関節を特定します
• 顔認識：画像内の人物を識別します

人気のアーキテクチャ

• 分類：ResNet、VGG、EfficientNet、Vision Transformer
• 検出：YOLO、Faster R-CNN、SSD、RetinaNet
• セグメンテーション：U-Net、DeepLab、Mask R-CNN
• 姿勢推定：OpenPose、PoseNet、HRNet

Python による実装

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.patches as patches
from PIL import Image, ImageDraw
import torch
import torch.nn as nn
from torch.utils.data import DataLoader, TensorDataset
from torchvision import transforms, models, datasets
import tensorflow as tf
from tensorflow import keras
from tensorflow.keras import layers
import cv2
from sklearn.metrics import accuracy_score, confusion_matrix
import seaborn as sns
import warnings
warnings.filterwarnings('ignore')

print("=== 1. Image Classification CNN ===")

# Define image classification model
class ImageClassifierCNN(nn.Module):
    def __init__(self, num_classes=10):
        super().__init__()
        self.features = nn.Sequential(
            nn.Conv2d(3, 32, kernel_size=3, padding=1),
            nn.ReLU(inplace=True),
            nn.BatchNorm2d(32),
            nn.MaxPool2d(2, 2),

            nn.Conv2d(32, 64, kernel_size=3, padding=1),
            nn.ReLU(inplace=True),
            nn.BatchNorm2d(64),
            nn.MaxPool2d(2, 2),

            nn.Conv2d(64, 128, kernel_size=3, padding=1),
            nn.ReLU(inplace=True),
            nn.BatchNorm2d(128),
            nn.MaxPool2d(2, 2),
        )

        self.classifier = nn.Sequential(
            nn.Linear(128 * 4 * 4, 256),
            nn.ReLU(inplace=True),
            nn.Dropout(0.5),
            nn.Linear(256, num_classes)
        )

    def forward(self, x):
        x = self.features(x)
        x = x.view(x.size(0), -1)
        x = self.classifier(x)
        return x

model = ImageClassifierCNN(num_classes=10)
print(f"Model parameters: {sum(p.numel() for p in model.parameters()):,}")

# 2. Object Detection setup
print("\n=== 2. Object Detection Framework ===")

class ObjectDetector(nn.Module):
    def __init__(self):
        super().__init__()
        # Backbone
        self.backbone = nn.Sequential(
            nn.Conv2d(3, 32, 3, padding=1),
            nn.ReLU(),
            nn.MaxPool2d(2, 2),
            nn.Conv2d(32, 64, 3, padding=1),
            nn.ReLU(),
            nn.MaxPool2d(2, 2),
        )

        # Bounding box regression
        self.bbox_head = nn.Sequential(
            nn.Linear(64 * 8 * 8, 128),
            nn.ReLU(),
            nn.Linear(128, 4)  # x, y, w, h
        )

        # Class prediction
        self.class_head = nn.Sequential(
            nn.Linear(64 * 8 * 8, 128),
            nn.ReLU(),
            nn.Linear(128, 10)  # 10 classes
        )

    def forward(self, x):
        features = self.backbone(x)
        features_flat = features.view(features.size(0), -1)

        bboxes = self.bbox_head(features_flat)
        classes = self.class_head(features_flat)

        return bboxes, classes

detector = ObjectDetector()
print(f"Detector parameters: {sum(p.numel() for p in detector.parameters()):,}")

# 3. Semantic Segmentation
print("\n=== 3. Semantic Segmentation U-Net ===")

class UNet(nn.Module):
    def __init__(self, num_classes=5):
        super().__init__()
        # Encoder
        self.enc1 = self._conv_block(3, 32)
        self.pool1 = nn.MaxPool2d(2, 2)
        self.enc2 = self._conv_block(32, 64)
        self.pool2 = nn.MaxPool2d(2, 2)

        # Bottleneck
        self.bottleneck = self._conv_block(64, 128)

        # Decoder
        self.upconv2 = nn.ConvTranspose2d(128, 64, 2, stride=2)
        self.dec2 = self._conv_block(128, 64)
        self.upconv1 = nn.ConvTranspose2d(64, 32, 2, stride=2)
        self.dec1 = self._conv_block(64, 32)

        # Final output
        self.out = nn.Conv2d(32, num_classes, 1)

    def _conv_block(self, in_channels, out_channels):
        return nn.Sequential(
            nn.Conv2d(in_channels, out_channels, 3, padding=1),
            nn.ReLU(inplace=True),
            nn.Conv2d(out_channels, out_channels, 3, padding=1),
            nn.ReLU(inplace=True)
        )

    def forward(self, x):
        enc1 = self.enc1(x)
        enc2 = self.enc2(self.pool1(enc1))
        bottleneck = self.bottleneck(self.pool2(enc2))

        dec2 = self.dec2(torch.cat([self.upconv2(bottleneck), enc2], 1))
        dec1 = self.dec1(torch.cat([self.upconv1(dec2), enc1], 1))

        return self.out(dec1)

unet = UNet(num_classes=5)
print(f"U-Net parameters: {sum(p.numel() for p in unet.parameters()):,}")

# 4. Transfer Learning
print("\n=== 4. Transfer Learning with Pre-trained Models ===")

try:
    # Load pre-trained ResNet18
    pretrained_model = models.resnet18(pretrained=True)
    num_ftrs = pretrained_model.fc.in_features
    pretrained_model.fc = nn.Linear(num_ftrs, 10)

    print(f"Pre-trained ResNet18 adapted for 10 classes")
    print(f"Parameters: {sum(p.numel() for p in pretrained_model.parameters()):,}")
except:
    print("Pre-trained models not available")

# 5. Image preprocessing and augmentation
print("\n=== 5. Image Preprocessing and Augmentation ===")

transform_basic = transforms.Compose([
    transforms.Resize((224, 224)),
    transforms.ToTensor(),
    transforms.Normalize(mean=[0.485, 0.456, 0.406],
                        std=[0.229, 0.224, 0.225])
])

transform_augmented = transforms.Compose([
    transforms.RandomRotation(20),
    transforms.RandomHorizontalFlip(),
    transforms.ColorJitter(brightness=0.2, contrast=0.2),
    transforms.RandomAffine(degrees=0, translate=(0.1, 0.1)),
    transforms.Resize((224, 224)),
    transforms.ToTensor(),
    transforms.Normalize(mean=[0.485, 0.456, 0.406],
                        std=[0.229, 0.224, 0.225])
])

print("Augmentation transforms defined")

# 6. Synthetic image data
print("\n=== 6. Synthetic Image Data Creation ===")

def create_synthetic_images(num_images=100, img_size=32):
    """Create synthetic images with shapes"""
    images = []
    labels = []

    for _ in range(num_images):
        img = np.ones((img_size, img_size, 3)) * 255

        # Randomly draw shapes
        shape_type = np.random.randint(0, 3)

        if shape_type == 0:  # Circle
            center = (np.random.randint(5, img_size-5), np.random.randint(5, img_size-5))
            radius = np.random.randint(3, 10)
            cv2.circle(img, center, radius, (0, 0, 0), -1)
            labels.append(0)

        elif shape_type == 1:  # Rectangle
            pt1 = (np.random.randint(0, img_size-10), np.random.randint(0, img_size-10))
            pt2 = (pt1[0] + np.random.randint(5, 15), pt1[1] + np.random.randint(5, 15))
            cv2.rectangle(img, pt1, pt2, (0, 0, 0), -1)
            labels.append(1)

        else:  # Triangle
            pts = np.array([[np.random.randint(0, img_size), np.random.randint(0, img_size)],
                           [np.random.randint(0, img_size), np.random.randint(0, img_size)],
                           [np.random.randint(0, img_size), np.random.randint(0, img_size)]])
            cv2.drawContours(img, [pts], 0, (0, 0, 0), -1)
            labels.append(2)

        images.append(img.astype(np.float32) / 255.0)

    return np.array(images), np.array(labels)

X_images, y_labels = create_synthetic_images(num_images=300, img_size=32)
print(f"Synthetic dataset: {X_images.shape}, Labels: {y_labels.shape}")
print(f"Class distribution: {np.bincount(y_labels)}")

# 7. Visualization
print("\n=== 7. Visualization ===")

fig, axes = plt.subplots(3, 3, figsize=(12, 10))

# Display synthetic images
for i in range(9):
    idx = i % len(X_images)
    axes[i // 3, i % 3].imshow(X_images[idx])
    axes[i // 3, i % 3].set_title(f"Class {y_labels[idx]}")
    axes[i // 3, i % 3].axis('off')

plt.suptitle("Synthetic Image Dataset", fontsize=14, fontweight='bold')
plt.tight_layout()
plt.savefig('synthetic_images.png', dpi=100, bbox_inches='tight')
print("Synthetic images saved as 'synthetic_images.png'")

# 8. Model architectures comparison
print("\n=== 8. Architecture Comparison ===")

architectures_info = {
    'CNN': ImageClassifierCNN(),
    'ObjectDetector': ObjectDetector(),
    'U-Net': UNet(),
}

arch_data = {
    'Architecture': list(architectures_info.keys()),
    'Parameters': [sum(p.numel() for p in m.parameters()) for m in architectures_info.values()],
    'Use Case': ['Classification', 'Object Detection', 'Segmentation']
}

arch_df = pd.DataFrame(arch_data)
print("\nArchitecture Comparison:")
print(arch_df.to_string(index=False))

# Visualization
fig, axes = plt.subplots(1, 2, figsize=(14, 5))

# Parameters comparison
axes[0].barh(arch_df['Architecture'], arch_df['Parameters'], color='steelblue')
axes[0].set_xlabel('Number of Parameters')
axes[0].set_title('Model Complexity Comparison')
axes[0].set_xscale('log')

# Use cases
use_cases = ['Classification', 'Detection', 'Segmentation',
            'Classification', 'Detection', 'Segmentation']
colors_map = {'Classification': 'green', 'Detection': 'orange', 'Segmentation': 'red'}
bar_colors = [colors_map[uc] for uc in arch_df['Use Case']]
axes[1].bar(arch_df['Architecture'], [1, 1, 1], color=bar_colors, alpha=0.7)
axes[1].set_ylabel('Primary Task')
axes[1].set_title('Architecture Use Cases')
axes[1].set_ylim([0, 1.5])

plt.tight_layout()
plt.savefig('cv_architecture_comparison.png', dpi=100, bbox_inches='tight')
print("\nArchitecture comparison saved as 'cv_architecture_comparison.png'")

# 9. Bounding box visualization
print("\n=== 9. Bounding Box Visualization ===")

fig, ax = plt.subplots(figsize=(10, 8))
ax.imshow(X_images[0])

# Draw sample bounding boxes
bboxes = [
    (5, 5, 15, 15),   # x1, y1, x2, y2
    (18, 10, 28, 20),
    (8, 20, 18, 28)
]

for bbox in bboxes:
    rect = patches.Rectangle((bbox[0], bbox[1]), bbox[2]-bbox[0], bbox[3]-bbox[1],
                            linewidth=2, edgecolor='red', facecolor='none')
    ax.add_patch(rect)

ax.set_title('Bounding Box Detection Example')
ax.axis('off')
plt.savefig('bounding_boxes.png', dpi=100, bbox_inches='tight')
print("Bounding box visualization saved as 'bounding_boxes.png'")

print("\nComputer vision setup completed!")

一般的な CV アーキテクチャ

• 分類：ResNet、EfficientNet、Vision Transformer
• 検出：YOLO v5、Faster R-CNN、RetinaNet
• セグメンテーション：U-Net、DeepLab v3、Mask R-CNN
• トラッキング：SORT、DeepSORT、ByteTrack

画像の前処理

• 標準的なサイズへのリサイズ
• ImageNet の統計値を使った正規化
• データ拡張（回転、反転、クロップ）
• 色空間の変換

評価指標

• 分類：Accuracy、Precision、Recall、F1
• 検出：mAP（平均適合率）、IoU
• セグメンテーション：IoU、Dice 係数、Hausdorff 距離

成果物

• 学習済みビジョンモデル
• 推論パイプライン
• 性能評価
• 可視化結果
• モデル最適化レポート
• デプロイガイド