🖼️ JFIF 转 PDFJFIF to PDF Converter
把 .jfif 图片（从网页、微信、WhatsApp 保存下来的常见格式）转换为 PDF：多张合并、调整顺序，直接保留原 JPEG 数据不再二次压缩，画质无损，可选 A4 等纸张，本地完成。Convert .jfif images — the format browsers, WeChat and WhatsApp often save — into a PDF. Combine and reorder several; the original JPEG data is embedded without recompression, so quality is unchanged, with A4 and other page sizes. Done locally.
使用说明与常见问题How-to & FAQ
「JFIF 转 PDF」是什么？What is the JFIF to PDF Converter tool?
把 .jfif 图片（从网页、微信、WhatsApp 保存下来的常见格式）转换为 PDF：多张合并、调整顺序，直接保留原 JPEG 数据不再二次压缩，画质无损，可选 A4 等纸张，本地完成。Convert .jfif images — the format browsers, WeChat and WhatsApp often save — into a PDF. Combine and reorder several; the original JPEG data is embedded without recompression, so quality is unchanged, with A4 and other page sizes. Done locally.
如何使用「JFIF 转 PDF」？How do I use the JFIF to PDF Converter tool?
在「JFIF 转 PDF」中，按需设置「页面大小」、「方向」、「页边距 (0–50 mm)」、「图片压缩」、「JPEG 质量 (30–100)」等选项，然后点击「生成 PDF」、「清空」按钮即可。支持拖放文件。In the JFIF to PDF Converter: Set "Page size", "Orientation", "Margin (0–50 mm)", "Image compression", "JPEG quality (30–100)", then click "Create PDF", "Clear". Drag-and-drop files is supported.
JFIF 是什么格式？What is JFIF?
JFIF（JPEG File Interchange Format）就是普通的 JPEG 图片，只是扩展名不同。Windows 和一些网站下载图片时会保存为 .jfif，很多上传表单因扩展名不认识而拒绝它；转成 PDF 后就能提交或打印。JFIF (JPEG File Interchange Format) is an ordinary JPEG with a different extension. Windows and some websites save downloads as .jfif, and many upload forms reject the unfamiliar extension; as a PDF it can be submitted or printed.
会降低画质吗？Will quality drop?
默认（“自动”）会把 JPEG 数据原样放进 PDF，不重新压缩，画质和原图完全一样；只有手动选择较低 JPEG 质量时才会重新编码。By default (Auto) the JPEG data is placed in the PDF as is, without recompression, so quality matches the original exactly; it is re-encoded only if you choose a lower JPEG quality yourself.
页面大小和页边距怎么选？How do I choose page size and margins?
“按图片尺寸”让每页正好等于图片大小（按图片自带的 DPI 换算，没有 DPI 信息时按 96 DPI），没有白边；选 A4 / Letter 等标准纸张时，图片会等比例缩放并居中，方向选“自动”时横图自动用横向页面。"Image size" makes each page exactly the size of its image (using the image's own DPI, or 96 DPI if none is stored), with no white border. With A4, Letter and other paper sizes the image is scaled proportionally and centred; with orientation on Auto, landscape images get landscape pages.
图片会上传吗？Are my images uploaded?
不会。解码和生成 PDF 都在你的浏览器里完成（pdf-lib），图片不会离开你的设备。No. Decoding and PDF creation both happen in your browser (pdf-lib); your images never leave your device.
「JFIF 转 PDF」免费吗？需要注册吗？Is the JFIF to PDF Converter free? Do I need an account?
「JFIF 转 PDF」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The JFIF to PDF Converter is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.