목차
PDF와 PDF/A는 비슷해 보이지만 다른 목적을 위해 사용됩니다. 각 형식을 언제 사용해야 하는지 이해하는 것은 문서 아카이빙, 법적 준수 및 파일이 수년간 접근 가능하도록 보장하는 데 중요합니다.
If you have ever received a PDF that looked different on someone else's computer, or been told by a government agency that your submission must be in "PDF/A format," you know the confusion surrounding PDF variants. This guide demystifies the difference between standard PDF and the PDF/A archival format, explains every version and conformance level, and shows you exactly how to convert between the two.
PDF와 PDF/A란?
두 형식 모두 동일한 기반을 공유하지만 다른 목표와 제한 사항을 가지고 있습니다:
표준 PDF
Portable Document Format (PDF)은 문서 교환을 위해 설계되었습니다. 양식, 멀티미디어, JavaScript 및 외부 링크와 같은 대화형 기능을 지원합니다. PDF는 뷰어의 소프트웨어와 사용 가능한 글꼴에 따라 다르게 보일 수 있습니다.
PDF/A (아카이브)
PDF/A는 장기 보존을 위해 설계된 ISO 표준화 버전입니다. 파일 내에 모든 필요한 리소스를 포함하고 향후 렌더링 문제를 일으킬 수 있는 기능을 금지합니다.
PDF/A는 2005년에 ISO 19005-1로 처음 발행되었습니다. 10년, 50년, 심지어 100년 후에도 문서가 정확히 동일하게 보이도록 보장합니다.
PDF와 PDF/A의 주요 차이점
두 형식의 상세한 비교는 다음과 같습니다:
| 기능 | PDF/A | |
|---|---|---|
| 글꼴 포함 | 선택 | 필수 |
| JavaScript | ✅ | ❌ |
| 암호화 | ✅ | ❌ |
| 외부 참조 | ✅ | ❌ |
| XMP 메타데이터 | 선택 | 필수 |
| 색 공간 | 모두 | 장치 독립적 |
PDF/A 버전 설명
PDF/A는 여러 버전을 거쳐 발전해 왔으며, 각 버전은 새로운 기능을 추가했습니다:
PDF/A-1
PDF 1.4 기반. 엄격한 요구 사항을 가진 원래 표준. 하위 집합: PDF/A-1a (접근성) 및 PDF/A-1b (기본).
PDF/A-2
PDF 1.7 기반. JPEG2000, 투명도 및 PDF/A 파일 포함 지원 추가. 오늘날 가장 널리 사용되는 버전.
PDF/A-3
PDF/A-2와 동일하지만 모든 파일 유형(Excel, XML 등)을 첨부 파일로 포함 가능.
PDF/A-4
PDF 2.0 기반. 간소화된 적합성 수준과 현대적 기능을 갖춘 최신 버전.
Conformance Levels Explained
Each PDF/A version comes in different conformance levels, designated by a letter suffix. Understanding these is important when an organization specifies a particular requirement like "PDF/A-2b."
Level b (Basic)
The minimum conformance level. It ensures the visual appearance of the document is preserved long-term. Fonts are embedded, prohibited features are removed, and color spaces are standardized. However, Level b does not guarantee that text can be reliably extracted or searched -- the focus is purely on visual reproduction.
Level a (Accessible)
Builds on Level b by requiring the document to be "tagged" with a logical structure. This means screen readers can interpret headings, paragraphs, tables, and reading order. Level a is essential for organizations that must meet accessibility standards (like Section 508 in the US or EN 301 549 in the EU). Creating a Level a document requires more effort during authoring, as the document structure must be explicitly defined.
Level u (Unicode)
Introduced in PDF/A-2, Level u sits between b and a. It requires that all text in the document maps to Unicode characters, ensuring text can be searched and extracted reliably. However, unlike Level a, it does not require full structural tagging. This makes it a practical middle ground for organizations that need searchable archives but do not require full accessibility compliance.
When in doubt, target PDF/A-2b. It is the most widely accepted conformance level, supported by all major archival systems, and does not require the complex structural tagging that Level a demands.
각 형식 사용 시기
표준 PDF 사용 시:
- 즉각적인 사용 또는 협업을 위한 문서 공유
- 양식이나 멀티미디어와 같은 대화형 기능이 필요한 경우
- 파일 크기가 중요한 경우 (PDF/A 파일은 일반적으로 더 큼)
- 비밀번호 보호와 같은 보안 기능이 필요한 경우
PDF/A 사용 시:
- 장기 아카이빙 또는 보존이 필요한 경우
- 법적 또는 규제 준수가 요구되는 경우
- 수십 년 후에도 문서를 읽을 수 있어야 하는 경우
- 정부나 의료 분야의 공식 기록 작성
How to Validate PDF/A Compliance
Just because a PDF looks correct does not mean it conforms to the PDF/A standard. Validation is the process of checking whether a file meets all the requirements of a specific PDF/A version and conformance level.
Why Validation Matters
Many organizations -- particularly government agencies, courts, and archives -- reject non-compliant files outright. If you submit a PDF that claims to be PDF/A but fails validation, your submission may be returned. Validating before sending avoids delays and frustration.
Validation Tools
- Adobe Acrobat Pro: Go to View > Navigation Panels > Standards, and click "Verify Conformance." Acrobat will report any violations found.
- veraPDF (free, open source): The industry-standard validator for PDF/A. It supports all versions and conformance levels and produces detailed compliance reports. Available at
verapdf.org. - Online validators: Several web-based tools can check PDF/A compliance by uploading your file. These are convenient for occasional checks.
Common Validation Errors
The most frequent issues that cause PDF/A validation to fail include:
- Missing embedded fonts: Every font used in the document must be fully embedded. System fonts referenced but not embedded will cause a failure.
- Transparency issues: PDF/A-1 does not support transparency. If your document uses semi-transparent elements, you must either flatten them or target PDF/A-2 or later.
- Missing XMP metadata: PDF/A requires XMP (Extensible Metadata Platform) metadata in the document. Some PDF generators omit this.
- Forbidden annotations: Certain annotation types (like 3D content or file attachments in PDF/A-1) are not permitted.
Common PDF/A Conversion Issues
Converting a standard PDF to PDF/A is not always seamless. Here are the issues you are most likely to encounter and how to resolve them:
Color Space Problems
PDF/A requires device-independent color spaces (like sRGB or ICC-based profiles) instead of device-dependent ones (like DeviceRGB). If your source document uses device-dependent colors, the conversion tool must add an appropriate ICC profile. Most conversion tools handle this automatically, but the colors may shift slightly in the process.
Interactive Form Fields
PDF/A-1 and PDF/A-2 do not support JavaScript, which means form fields that rely on scripts will lose their functionality. Static form fields (dropdowns, text inputs, checkboxes) are preserved in PDF/A-2 and later, but any calculated fields or validation scripts will be stripped. If your document has interactive forms, complete them before converting to PDF/A.
Embedded Multimedia
Audio and video content is not permitted in PDF/A-1 or PDF/A-2. PDF/A-3 allows embedded files of any format but does not guarantee they will be playable. If your document contains multimedia, you will need to remove it or replace it with static content (screenshots, transcripts).
File Size Increase
PDF/A files are typically larger than their standard PDF counterparts because fonts must be fully embedded and certain compression techniques are restricted. Expect a 10-50% size increase. If the resulting file is too large, use the PDF compressor afterward -- just ensure the compression tool preserves PDF/A compliance.
PDF를 PDF/A로 변환하는 방법
PDF-Ninja로 일반 PDF를 PDF/A로 변환하는 것은 간단합니다:
- PDF 파일을 PDF/A 변환기에 업로드
- 필요한 PDF/A 버전 선택 (대부분의 용도에 PDF/A-2b 권장)
- 변환 클릭하고 처리 대기
- 호환되는 PDF/A 파일 다운로드
After conversion, always validate the output as described in the validation section above. Some conversion tools produce files that visually appear correct but fail strict compliance checks.
The best PDF/A documents start their life as PDF/A. If possible, configure your source application (Word, InDesign, LibreOffice) to export directly to PDF/A rather than creating a standard PDF and converting it later. This avoids most conversion issues entirely.
결론
PDF와 PDF/A 중 선택은 특정 요구 사항에 따라 달라집니다. 일상적인 문서 공유에는 표준 PDF가 더 많은 유연성을 제공합니다. 아카이빙, 법적 준수 또는 장기 보존을 위해서는 PDF/A가 수십 년간 문서에 접근 가능하고 변경되지 않도록 보장합니다. 무료 변환기로 필요할 때 언제든지 호환되는 PDF/A 파일을 쉽게 만들 수 있습니다.
Whether you are archiving corporate records, submitting legal filings, or preserving historical documents, understanding the differences between PDF and PDF/A empowers you to make the right format choice. For most archival needs, PDF/A-2b strikes the best balance between compatibility and ease of creation. Use the PDF to PDF/A converter to get started, and explore our related guides on compressing PDFs and electronic signatures.
Frequently Asked Questions
Can I convert a PDF/A back to a regular PDF?
Technically, yes. Opening a PDF/A in most editors and re-saving it as a standard PDF removes the PDF/A restrictions. However, this defeats the purpose of archival formatting. If you need to edit a PDF/A document, edit it and then re-convert to PDF/A when done.
Does PDF/A support digital signatures?
Yes. PDF/A-2 and later versions support digital signatures, including PAdES (PDF Advanced Electronic Signatures). This makes PDF/A suitable for legally signed documents that need long-term archival. See our guide on signing PDFs legally for more details.
Which PDF/A version should I use?
For most purposes, PDF/A-2b is the recommended choice. It supports JPEG2000 compression and transparency (unlike PDF/A-1), is widely supported by archival systems, and has a lower creation barrier than Level a conformance. Only use PDF/A-1 if explicitly required by a regulatory body.
Why is my PDF/A file larger than the original PDF?
PDF/A requires all fonts to be fully embedded and prohibits certain compression methods. These requirements increase file size by 10-50% compared to a standard PDF. You can use PDF compression tools afterward, but verify that the compressed file still passes PDF/A validation.
Is PDF/A the same as PDF/X or PDF/E?
No. PDF/A is for archiving, PDF/X is for print production (ensuring reliable printing), and PDF/E is for engineering documents. Each is an ISO standard subset of PDF optimized for a specific use case. They share the same base format but have different restrictions and requirements.