2007.07.03 18:37 "[Tiff] BigTIFF extension?", by Phil Harvey

2007.07.05 16:30 "Re: [Tiff] 16-Bit-Per-Channel Lossless Compression", by Joris Van Damme


As I don't speak gdalese, what size do tiles have in your test? It's my opinion ideally efficient tiles over a broad range of compression modes, that fit workflow on today's machines best, are in the order of about 1 to 3 megabyte, not the legacy 8 kilobyte (uncompressed, of course). I believe that for some compression modes, tile size does have a considerable impact on efficienty.

You make many assumptions in the above statement, and particularly
about how applications store/access their pixels. I would not
encourage anyone to write such huge tiles.

There are many major factors which influence performance:

I have done considerable testing and benchmarking in various scenarios
and results usually show that data access sizes of 8K or 16K are best,
with performance diminishing past 32K.

Your huge tiles have these problems:

Though a number of your points are based on LibTiff's design, which is not ideal in that it buffers compressed and decompressed striles (=strips or tiles, whatever applies), I do think you make sense given that LibTiff design and a number of your points probably apply to AsTiff design as well. Likely my estimate of 1 to 3 megabyte for ideal strile size is a bit much.

Best regards,

Joris Van Damme
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