PDF เป็น PDF/A

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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.

วิธีทำงาน

1. 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.
2. 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.
3. 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.
4. For rasterise, set the resolution and leave keep text searchable on, so an invisible text layer is written behind the page images.
5. Press Convert to PDF/A.
6. 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.