[PDFBOX-4300] Reduce im memory buffers when creating grayscale images

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.0.11
• Component/s: PDModel
• Labels: optimization
• Assignee: Unassigned
• Reporter: Jesse Long
• Created: 27/Aug/18 10:39
• Updated: 22/Nov/18 02:12

Description

LosslessFactory uses ByteArrayOutputStreams when creating PDF image data. First, it creates a BAOS in which to store the data, then a BAOS in which to store the flate encoded data. Finally the flate encoded data is written to the PDImageXObject's stream.

We could instead create an empty PDStream, give it a filter, and write the image data directly into the stream. We then instantiate a PDImageXObject giving it the already created stream.

This would dramatically reduce RAM requirement if a scratchfile is in play.