PDF 转 TIFF
把页面渲染成 TIFF，支持多页，分辨率随你选。
这款工具完全在你的浏览器中运行。文件从不上传，你可以在浏览器的网络标签中亲自验证这一点。 亲自验证：打开浏览器的网络标签观察。你会看到一个查询你是否还有剩余任务的小请求，只包含工具名称和一段哈希，绝不会包含文件。
这款工具的作用
TIFF is not a format anyone picks for pleasure. People arrive here because a court filing system, a medical archive, a records department or a fax gateway will accept nothing else, usually at 300 dpi and often bilevel. So this renders each page at the resolution you set and writes it into a TIFF, by default as one multi-page file rather than a folder of separate ones.
Use it when something on the other end has specified TIFF: an e-filing portal, a document management system that only indexes TIFF, an archive with a retention standard written before PDF existed, or a fax service that takes image files.
工作原理
- Drop the PDF onto this page. Files up to 300 MB are accepted, because scans run large.
- Set the resolution. 300 dpi is what most filing systems ask for; 200 is enough for on-screen review and 600 is for archival capture of fine detail.
- Choose colour, gray or bilevel. Bilevel is the black-and-white setting those systems usually mean, and it is what keeps the file small.
- Leave One multi-page file on unless the receiving system genuinely wants a separate image per page.
- Press Convert to TIFF and download the result.
Bilevel is the setting that decides whether the result is manageable. An A4 page at 300 dpi is about 8.7 million pixels, which is roughly 25 MB of colour data before compression; bilevel packs eight pixels into a single byte and brings the same page down to a little over one megabyte before compression, and to a few hundred kilobytes after it. The polarity is handled correctly, which matters more than it sounds - white has to be zero, and getting that backwards produces a negative of the page.
Pages are rendered to PNG on the way out of the renderer and then re-encoded into the TIFF, rather than passing through JPEG first. That avoids throwing away detail in a lossy step that nobody asked for, which is the sort of quiet quality loss an archival conversion should not contain.
Compression is deflate or none, and nothing else. Deflate is lossless, widely readable and does well on text pages. Group 4 fax compression, which a few older bilevel workflows expect and which would be smaller still, is not written here - if a system rejects the output for that reason, it is the one thing this tool cannot give you.
Rendering happens on your device through PDF.js, and the TIFF is assembled there too. Medical and legal documents are the usual traffic for this converter, so it is worth being explicit: no page image is produced on a server, and nothing about the file is sent anywhere.
这款工具做不到的事
- A TIFF is pixels. Text stops being selectable and searchable the moment a page is rendered, so nobody will find a word in the result.
- Deflate is the only compression offered, so a colour TIFF at 300 dpi is many times the size of the PDF it came from. JPEG and Group 4 fax compression are not written.
常见问题
- 我为什么要 TIFF 而不是 PDF？
- 几乎总是因为别的东西非要它不可。法院电子提交门户、医院病历系统、一些政府归档系统和传真网关都是围着 TIFF 建的，至今没变。如果没有什么在向你索要 TIFF，那么 PDF 在各方面都是更好的文件。
- 黑白二值是什么意思，我该用吗？
- 黑白二值就是每像素一比特：每个像素非黑即白，中间没有灰。大多数归档系统说“黑白 TIFF”时指的就是它，它能把一张 300 dpi 的页面从几十兆字节压到几百千字节。文字文档和表单用它；照片或带渐变的图不要用，因为它会丢掉黑白之间的一切。
- 我能把整个文档做成一个文件吗？
- 可以，而且这是默认设置。所有页面会作为链接在一起的图像文件目录写进一个 TIFF，这正是文档管理系统期望的形式。如果你确实需要每页一个图像文件，就关掉这个选项，每个文件都带前导零编号以保证排序正确。
- TIFF 太大了，我该改什么？
- 两个设置，按此顺序。如果文档以文字为主，先把颜色模式切成黑白二值，这是单项最大的节省——相对灰度大约缩小八倍。然后调低分辨率：200 dpi 是 400 dpi 四分之一的像素，除非另有要求，通常已经够用。
- 为了渲染，我的文档会被发到什么地方吗？
- 不会。每一页都在你浏览器的 Web Worker 里栅格化，TIFF 也在那里组装，所以病历或法庭证物绝不会离开你的设备。无论文件多大都不上传，也没有队列要等。