PDF 资源
有关 PDF 的参考指南：A0–A10 纸张尺寸、PDF/A、PDF/X、DPI 分辨率、压缩和电子签名。清晰而深入的讲解。
Paper Sizes A0 to A10: Dimensions in mm, cm, inches and pixels
Complete table of A-series paper sizes (ISO 216), from A0 to A10, with dimensions in millimeters, centimeters, inches and pixels at 72 and 300 DPI.
阅读资源DPI, resolution and pixels: the complete guide for your PDFs and images
Understand DPI, resolution and pixels: the calculation formula, A4 sizes in pixels, and recommended DPI for screen, printing and OCR.
阅读资源Lossless vs lossy PDF compression: how to shrink a PDF without losing quality
Understand lossless and lossy PDF compression, the role of DPI, and the best practices to shrink a PDF while keeping it sharp and readable.
阅读资源PDF/A: The Long-Term Archiving Format Explained
Understand PDF/A (ISO 19005): what it is for, how it differs from a normal PDF, its conformance levels, and how to create one.
阅读资源PDF/X: the format for professional printing, explained
PDF/X is the ISO standard for reliable prepress exchange: embedded fonts, CMYK colors and a defined output intent for professional printing.
阅读资源Electronic signatures explained: types, legal value and uses
Types of electronic signature, the eIDAS and ESIGN frameworks, legal value and best practices: a clear guide to signing a PDF with confidence.
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