PDF 转 PDF/A
为长期归档准备文档，并说明那解决不了什么。
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
PDF/A is the archival profile: a set of restrictions meant to keep a file rendering the same way in decades to come, mostly by insisting that everything the page needs is inside the file. This writes the parts of that promise a browser can write honestly - the XMP conformance identification, an sRGB output intent with an embedded ICC profile, the structure markers and a document language - and, if you ask for it, re-renders the pages so no missing font is left to fail.
Court filings, grant applications, tender portals and records systems that reject anything not marked PDF/A, and any document you expect to open long after the software that produced it has stopped being installed anywhere.
工作原理
- Drop the PDF onto this page. It must not be encrypted - PDF/A forbids encryption, so a protected file is refused with a link to Unlock PDF.
- Choose the part. PDF/A-2 suits almost every current requirement, PDF/A-1 is what older archives ask for, and PDF/A-3 differs mainly in allowing attached source files.
- Leave the mode on metadata to keep the text as vector text, or switch to rasterise if the document uses fonts it did not embed.
- For rasterise, set the resolution and leave keep text searchable on, so an invisible text layer is written behind the page images.
- Press Convert to PDF/A.
- Check the result with a validator such as veraPDF. This tool cannot check its own conformance.
Metadata mode writes several things at once, because a validator checks all of them. The Info dictionary and the XMP packet are always written together, since modern readers prefer XMP and a disagreement between the two is among the first things a validator flags. An sRGB output intent is added with a real ICC profile embedded, along with the marked-content flag, a document language and matching document and instance identifiers. For PDF/A-1 the header is also written as PDF 1.4 and object streams are left out, because part 1 is defined against that older version.
Fonts are where conversion honestly stops. PDF/A requires every font the page uses to be embedded, and a font the original left out cannot be conjured up afterwards - the glyph shapes are not there. This is the most common reason a file fails validation, and it is why rasterise mode exists: when every page is an image there are no text fonts left to embed.
Rasterise is a real trade. Vector text becomes pixels, so the file usually grows and zooming or printing past the resolution you chose looks soft. To keep the document usable an invisible text layer is drawn behind the images at the original word positions, so search and copy still work - and that layer uses an embedded font rather than a standard one, because a standard font would break the very requirement the mode exists to satisfy.
Conformance level A asks for more than level B: a tagged structure tree describing the reading order and role of everything on the page. That tree cannot be built after the fact from a finished PDF, so unless the source was already tagged, choosing A writes a claim nothing here can fulfil. Level B is the honest default, and it is what most submission portals actually require.
The conversion runs entirely on your device, which matters for the filings, contracts and records that usually end up here. The tool still cannot validate its own output, for a related reason: verification belongs to an independent validator, not to the program that wrote the file.
这款工具做不到的事
- The tool cannot validate its own output. It writes a conformance claim into the file; whether the file truly conforms is what an independent validator such as veraPDF says it is.
- A font the source document did not embed cannot be embedded now, and that is the most common reason a file fails validation. Rasterise mode is the way around it.
- Rasterise replaces vector text with page images, so the file usually grows and enlarged printing looks softer than the original.
常见问题
- PDF/A 是什么，为什么会有地方要它？
- 它是 PDF 的一种归档配置，为长期保存而标准化。它禁止任何渲染依赖外部世界的东西——未嵌入的字体、加密、外部内容、不可预测的颜色——好让文件在二十年后仍然看起来一样。法院、档案馆和采购门户之所以要它，是因为它们必须能在你的软件早已不复存在很久之后，还能打开你提交的东西。
- 元数据还是栅格化——我需要哪种模式？
- 从元数据开始。它会添加标识、输出意图、ICC 配置文件和结构标记，同时把文本保留为文本，这让文件保持小巧、可搜索且清晰。只有当校验因字体而失败时才切换到栅格化，因为它通过把页面变成图像来彻底解决那个问题。
- 输出保证能通过校验吗？
- 不保证，而任何告诉你保证的工具，都是在要你相信一个无人核验过的说法。这里会写入合规声明，以及关于它的、一切可以事后添加的东西，但它无法逐页检查某些部分所禁止的透明或图像编码，也无法嵌入一个缺失的字体。在提交任何要紧的东西之前，请运行 veraPDF。
- 校验说有个字体没有嵌入。我能做什么？
- 要么回到制作这个 PDF 的程序里，开启字体嵌入后重新导出一次，那样结果更好；要么在这里使用栅格化模式。栅格化通过去掉作为文本的文字来消除这个问题，并在图像后面留下一层不可见的可搜索图层。
- 我必须上传这个文档吗？
- 不必。元数据的写入和页面的渲染都在你的浏览器中进行，所以立案文件和合同绝不会离开设备。这可以在开发者工具的网络标签里核实，而且页面加载一次之后，它在断网时也能工作。