PDF (Portable Document Format) is a compact graphic file format developed by Adobe Systems Inc. that allows distribution of documents with the original formatting including pictures and fonts among various computer operating systems. Though many applications have an option to create PDF files, they vary in purpose and quality. From the same original, a small low-resolution RGB file or a larger high-resolution CMYK PDF can be created. A long list of options allow security features, layers, editable fields, and more.
Over the years, Adobe Systems has enhanced the technology of PDF to allow end-user annotation with Adobe Reader. Though PDF files can be created with Adobe Acrobat Professional (with included Distiller), Acrobat and PDF versions differ. A measure of backwards compatibility allows most PDFs to be opened in a prior version though some anomalies may be present. For example, opening a PDF 1.5 file that supports hidden layers within Adobe Reader 4 results in all layers becoming visible.
- Acrobat 4 (PDF 1.3): rasterizes shadows into images
- Acrobat 5 (PDF 1.4): layers shadows as alpha channel over images
- Acrobat 6 (PDF 1.5): supports hidden layers and more security options
- Acrobat 7 (PDF 1.6): advanced file security options; smaller file size
- Acrobat 8 (PDF 1.7): online collaboration option; enhanced Reader
- Acrobat 9 (PDF 1.8): supports native Adobe Flash and 3d content
Reactive Imaging outputs files in a PDF workflow. This means most files are converted to PDF before printing (JPEG or TIFF files may be printed directly). Each listed PDF version is recognized. However, from InDesign CS, rasterized shadows reproduce better (softer) with Acrobat 4 (PDF 1.3) so this older version is preferred when using the first Creative Suite. InDesign CS3 produces better shadows and smaller files so Acrobat 8 (PDF 1.7) can be suitable if using current software.
Acrobat 9 (PDF 1.8) is a multi-media upgrade that has little impact on files destine for printing. Acrobat 8 or lower is recommended.