[PDFBOX-4156] Possible optimization of SampledImageReader.from8bit by using InterleavedRaster

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0.8
• Fix Version/s: 2.0.10, 3.0.0 PDFBox
• Component/s: Rendering
• Labels: optimization
• Flags: Patch
• Assignee: Tilman Hausherr
• Reporter: Itai Shaked
• Created: 18/Mar/18 08:13
• Updated: 21/Jun/18 20:27
• Resolved: 24/Mar/18 13:49

Description

I noticed SampledImageReader.from8Bit assumed the source data to be interleaved, which means if the target raster uses an interleaved sample model, the data can by directly copied. 

This can save 10-15% of total render time in files with large 8-bit images (tested on samples from PDFBOX-2092 , PDFBOX-3791 and the file "gs-bugzilla690022.pdf" from PDFBOX-4151). 

In PDFBOX-2092 there is a discussion about how the sample model must be Banded, but I couldn't find a place in the code that directly relies on this, and the few tests I have run did not reveal problems. Perhaps the constraint is obsolete, or else it means custom sample models cannot be used?