blowekamp
May 8, 2019, 8:55pm
15
dzenanz:
I am currently leaning towards using blosc+zstd on compression level 2 as the default. Also, I think we should expose SetCompressionLevel in itk::ImageIOBase , which is currently implemented only by a few IOs (e.g. PNG , MINC ). @blowekamp suggested also exposing SetCompressor , which would allow programatically preserving backwards compatibility if so desired. A configure-time option for backwards compatible compression is already planned.
Here is the PR for this improvement:
InsightSoftwareConsortium:master ← blowekamp:AddCompressionOptionsToImageIOBase
opened 08:44PM - 08 May 19 UTC
There are two primary characterizations of compression level. 1) the
0-100 vers… ion for JPEG-like lossy compression which ranges 0-100 and
2) the loss-less with quality 0-9.
This implementation has the ImageIO set the expected range and enforce
the range by clamping when setting the value.
The CompressionLevel is mostly straight forward. With the caveat: some compression algos have the range 0-100, while others have 0-9 (deflate/zlib based). In this implementation I choose to have each ImageIO define a max. This preserves compatibility, at the expense of not having a consistent range.
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