PNGを無料でオンライン圧縮する方法 — 画像サイズ削減
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easytools24の画像圧縮ツールで無料でPNGファイルを圧縮できます。PNGを追加して透明度を保持した小さいバージョンをダウンロード。すべてブラウザ内で処理されます。
What Is PNG Compression?
PNG compression reduces the file size of PNG images while preserving their lossless quality and transparency. Unlike JPEG compression, PNG compression does not discard visual data — every pixel remains intact.
PNG files are typically larger than JPEGs because they use lossless compression. However, optimization techniques like color palette reduction and metadata stripping can significantly reduce PNG file sizes without any visible quality change.
Why Compress PNG Files?
PNG files are essential for graphics with transparency, but they can be large:
1. Web Performance
Unoptimized PNG files are often the biggest performance bottleneck on websites. A single uncompressed PNG logo or icon can be several hundred kilobytes. Compressing them improves page load speed and Core Web Vitals scores.
2. Preserve Transparency
Unlike JPG, PNG supports transparent backgrounds. When you need transparency for logos, icons, or overlays, PNG is the right format — and compression keeps file sizes manageable.
3. App and Game Assets
Mobile apps and games use PNG sprites and UI elements extensively. Compressing these assets reduces app download size and memory usage on user devices.
4. Design File Sharing
Designers frequently share PNG exports with clients and team members. Compressed PNGs are faster to upload, download, and preview in collaboration tools.
How to Compress PNG Online — Step-by-Step Guide
Reduce your PNG file sizes while keeping transparency and quality:
Step 1: Open the Compress Image Tool
Navigate to the Compress Image tool in any browser. No software installation required.
Step 2: Add Your PNG Files
Drag and drop your PNG images into the upload area. You can compress multiple PNG files at once for batch optimization.
Step 3: Compress
The tool optimizes your PNG files by reducing color depth where possible, stripping unnecessary metadata, and applying optimal compression algorithms. Transparency is fully preserved.
Step 4: Download Optimized PNGs
Download your compressed PNG files. The tool shows the size reduction achieved. Your original files remain unchanged on your device.
PNG Compression Tips
Use PNG Only When You Need It
If your image does not require transparency, consider saving as JPEG instead. JPEGs are naturally smaller. Reserve PNG for logos, icons, screenshots, and images with transparent areas.
Reduce Color Palette
Many PNG images use 24-bit color (16 million colors) when they only contain a few dozen distinct colors. Reducing to an 8-bit palette can shrink file size by 50-70% with no visible change.
Consider WebP as an Alternative
For web use, WebP format provides better compression than PNG while supporting transparency. However, PNG remains the safer choice for universal compatibility.
Common Use Cases
PNG compression is used by:
- Web developers optimizing logos, icons, and UI graphics
- Graphic designers sharing transparent assets with clients
- App developers reducing asset sizes for mobile applications
- Game developers optimizing sprite sheets and textures
- E-commerce stores using transparent product images on various backgrounds
- Content creators preparing PNG overlays for video and streaming
よくある質問
Does compressing PNG remove transparency?+
Is PNG compression lossless?+
Which is smaller, PNG or JPG?+
Is it safe to compress PNG files online?+
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