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BMP 转 JPG 转换器
将 BMP 位图图像转换为 JPG，并将文件大小压缩最高可达 95%。BMP 文件未压缩，体积庞大，不适合共享或网页使用。免费、即时、隐私保护。
为什么 BMP 文件如此庞大？
BMP（位图）是 Microsoft 于 1988 年开发的未压缩图像格式。每个像素以原始方式存储，完全不压缩。一个 4000×3000 像素的图像以 BMP 保存约为 34 MB，而同样的图像在 JPEG 质量 85 下仅约 2–4 MB。BMP 在早期 Windows 桌面图标时代还算合理，但在任何涉及文件共享或网页使用的现代场景中已显过时。
BMP 转 JPG：实际使用场景
- Windows 截图 ‑ 某些较旧的 Windows 工具默认将截图保存为 BMP。转换为 JPG 以便共享。
- 旧版 CAD 或医疗软件 ‑ 某些工业软件以 BMP 格式导出图像。
- 扫描文档 ‑ 老旧扫描仪有时输出 BMP。转换为 JPG 可大幅节省存储空间。
我应该将 BMP 转换为 JPG 还是 WebP？
对于摄影类 BMP，质量 85–90 的 JPG 是最佳选择——它能在约 3–5% 的 BMP 文件大小下提供出色的画质。对于图形、标志和边缘锐利的图像， 转换为 WebP ‑ 它对摄影和图形内容的处理都优于 JPEG。
常见问题
Typically 90–97% smaller. A 10 MB BMP image converted to JPG at quality 85 becomes roughly 300–700 KB. The exact ratio depends on image complexity, but BMP-to-JPG compression ratios of 20:1 to 50:1 are common for photographic content.
Yes - JPEG uses lossy compression while BMP is lossless. However, at quality 88–92 (this tool's default), the quality loss is imperceptible under normal viewing conditions. The trade-off of a 95% smaller file at virtually the same visible quality makes this conversion worthwhile in almost all cases.
Microsoft Paint historically defaulted to BMP as the native Windows bitmap format for simplicity and compatibility within the Windows ecosystem. Modern versions of Paint save as PNG by default instead. If you're still getting BMP files from Paint, use "File → Save As" and choose JPEG or PNG instead.
Yes - this tool runs entirely in your browser with no file size limit imposed by a server. However, very large BMPs (50 MB+) may be slow to process on older devices because the browser needs sufficient RAM to hold the uncompressed pixel data during canvas processing. Modern devices handle files up to 100 MB without issues.