Real world scenario: A client uses a pixel-accurate digital proofing tool that is consistently, correctly, and insanely accurate in identifying differences between two documents, even if the difference is a kerning pair, a graphic shifted by .005″, etc.
In a design group of 5+ people, we use carefully managed fonts (cloud-based font server, with no local additions or overrides), carefully managed application versions, carefully managed workstations, etc. to reduce any variability within PDFs we create. This includes carefully managed export settings, which are identical on each workstation.
When I export any one layout from each workstation, I can have as many different PDFs as evaluated by the digital proofing tool. I can confirm that the tool is accurate — while overall content is solid and the differences usually not noticeable to the naked eye, stuff like kerning pairs and text baselines can shift slightly (but noticeably) when comparing the PDFs to one another. Currently, our pdfs for proofing are not compliant to any PDF/x.
In testing, I’ve confirmed the same result is true with PDF/x-1a files — variation remains from workstation to workstation.
But when I generate PDF/X-4 files, we get identical results across the board. I presume this has to do with transparency flattening settings, which are not applied in the PDFx4 creation. I’m mid-evaluation to confirm that flattening settings are indeed identical both in the application and in the export settings for non-PDF/x-4 PDFs.
Are there other differences “under the hood” that would cause PDFs to not be identical when created with identical settings?
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