Slow web pages, upload size limits, and blurry images in messaging apps often have one thing in common: the original image is too large. The image compressor from Xian's Tools processes images directly in your browser, without uploading them to a server. Use it for screenshots, ID photos, product images, and other files you want to keep on your device.

Why no upload is needed

The tool runs a WebAssembly version of ImageMagick inside your browser. It reads and processes the selected image in local memory, then creates a download for the result. This means:

You do not have to wait for an image upload, even on a slow connection.

Closing the page ends the session and releases its processing data.

Processing speed depends on your device; large images can take longer.

How to compress an image

1. Open Image Compression, click Select File, or drag an image into the drop area.
2. The tool automatically processes the image once using the default quality of 75 and the original format.
3. Compare the original size, the size shown under After, and the Ratio.
4. To adjust the result, change Quality or Output Format, then click ReConvert.
5. Click Download to save the result.

What the quality slider changes

The same slider behaves differently depending on the format:

• JPG to JPG, including Original: sets JPEG quality. Lower values usually reduce file size but can introduce visible blocks and rough edges.
• PNG to PNG, including Original: reduces the color palette to approximately 64–256 colors and removes metadata. This can work well for icons, screenshots, and illustrations, but may cause banding in photographs.

作为起点，照片用 JPG，截图和图标保留 PNG。

建议设置

• 网站和产品照片：先试 JPG 质量 60–80，然后检查细节。节省幅度取决于源图像。
• 受上传限制的图片：从 75 开始，如有需要逐渐降到 50。
• 截图和文字较多的图片：保留 PNG，从 75 或更高开始；转换后检查文字和颜色渐变。
• 透明 Logo：保留 PNG，因为 JPG 会把透明区域变成白色背景。

如何解读比例

显示的比例是 compressed size / original size。结果为 35% 表示新文件是原始大小的 35%。接近或高于 100% 的值可能意味着源文件已被高效压缩，或所选输出格式需要更多空间。尝试其他格式或质量设置。

常见问题

图像尺寸会改变吗？

No. This tool changes quality and colors while preserving width and height. To reduce pixel dimensions, use Resize in Image Tools. Reducing dimensions can save more space than lowering quality alone.

Why is the compressed file larger?

This can happen when converting an already compressed JPG to PNG or processing an image that already uses a low quality setting. Keep the original format and adjust quality as needed.

Is EXIF metadata preserved?

JPG-to-JPG compression generally preserves existing metadata, while PNG output removes metadata. Keep this in mind if your photos contain capture dates or device information.

Can I compress a batch of images?

The current tool processes one image at a time.

Related tools

• Image Format Converter: convert between PNG and JPG.
• Image Cropper: remove unnecessary areas before compression.
• Image Tools: resize images, inspect image information, and create ICO files.