画像トリミング

🎬 Understanding Image Aspect Ratios

Aspect Ratio refers to the proportional relationship between an image's width and height. Since different devices and use cases require different aspect ratios, accurate cropping according to your purpose is important.

🔹 Common Aspect Ratios and Uses

💡 Best Practices for Aspect Ratio Selection

• Instagram Posts: 1:1 (square) recommended. 3:4 (portrait) also supported, but square looks best
• Profile Images: 1:1 (square). Universal across all platforms
• Passport Applications: Exactly 2:2.5 inch (413×531px) required. One-click support with this tool
• YouTube Thumbnails: 16:9 (1280×720px) is standard. Square may be cropped
• Facebook Cover Photos: 205:78 (820×312px) is standard. Unique ratio requires attention

📌 Different SNS platforms display images at different aspect ratios. Cropping to the optimal aspect ratio prevents unwanted cropping or blank spaces.

📊 Cropping and Image Quality

A common concern when cropping images is whether quality degrades. The answer is: cropping alone does not degrade quality. However, there are some important considerations.

🔹 Why Cropping Doesn't Degrade Quality

Cropping simply "removes" unwanted parts from the original image. Since there's no compression or color reduction, the quality of the remaining area is 100% preserved.

• Non-destructive editing: Original pixel information remains unchanged
• No format conversion: Compression settings remain unchanged unless converting formats like JPG→PNG
• Resolution changes but quality doesn't: Pixel dimensions decrease, but information per pixel remains the same

⚠️ Cases Where Quality May Degrade

• Re-saving with compression: High compression when saving as JPEG after cropping may cause degradation (this tool avoids this)
• Upscaling during crop: Cropping to a size larger than the original requires pixel interpolation, reducing quality
• Enlarging small images: Example: Cropping a 100×100px image to 1000×1000px output will appear pixelated

✅ Tips for Maintaining Quality

• Keep output size equal or smaller than original: No quality loss when cropping to smaller sizes
• Watch compression for JPEG: Recommended to save at high quality (80-90%)
• Consider PNG format: Lossless compression preserves quality (but larger file size)
• Use this tool: Browser-based processing avoids compression from multiple crop operations

📌 Conclusion: Cropping itself is non-destructive editing. However, slight quality loss may occur if the image is compressed as JPEG during download. For highest quality, consider saving as PNG or lossless WebP format.

🔒 Benefits of Client-Side Processing

This tool processes everything in your browser (client-side). This isn't just a technical choice—it significantly improves user privacy and convenience.

🛡️ Security and Privacy Benefits

• Images never sent to servers: Processing happens entirely on your device. Safe for confidential photos and screenshots
• Zero third-party viewing risk: No one, including operators, can view your images. Complete privacy protection
• No logging: Processing history and filenames are never recorded on servers. Completely private environment
• No network interception risk: No network transmission means no risk of man-in-the-middle (MITM) attacks

⚡ Performance Benefits

🌐 Mobile Advantages

• Saves data usage: No large image uploads to servers, reducing mobile data consumption
• Fast smartphone processing: Instant cropping without waiting for server responses
• Battery saving: Less network processing means less battery consumption

⚠️ Comparison with Other Online Image Tools: Many free image editing tools upload files to servers for processing. This introduces risks: (1) Confidential information leakage, (2) Slower processing, (3) File size limitations, (4) Upload time consumption. This tool solves all these issues.