This description of OPTIMIZE_RESOURCES_MODE leaves me with some uncertainty. It says it "optimizes resource handling" and supports "page content and resources," which sounds good. To me, a "resource" is something like an image or a font, but maybe there is a more technical meaning with PDFs.
However, the warning that "Not all document elements are merged" is concerning. This seems to conflict with the idea that resources are supported. I am worried about losing important features from the source documents.
My specific questions are:
What does "resource optimization" mean in this context? Does it simply deduplicate identical resources (e.g., if 10 source PDFs use the same font, only embed it once), or is there more to it?
What are the specific risks to fonts and images? For example, if two documents use different subsets of the same font, could using this mode cause text to disappear or become corrupted in the final document? Could an image be lost?
What are the "document elements" that are NOT merged in this mode? Does this refer to features like:
In short, what are the practical trade-offs and specific failure scenarios I should test for when choosing OPTIMIZE_RESOURCES_MODE over the safer, but potentially less efficient, PDFBOX_LEGACY_MODE?
You should know whether you need the items mentioned in (3) or not. The only use case I can think about is merge for printing when you're sure that there are no annotations and no visible signatures.