I have some raw data in hdf5 file format (lz4 compressed) this is really quick to read, whcih is nice ;-).
I then do some stuff to the data, and save it in new hdf5 files (noncompressed) which is unreasonable slow to read in comparison:
>> tic;rawpix = h5read('raw_data.h5','/h5/data/path',[1 1 1], [1 1 1]);toc
Elapsed time is 0.154878 seconds.
>> tic;manpix = h5read('treated_data.h5','/h5/data/path', [1 1 1], [1 1 1]);toc
Elapsed time is 0.400602 seconds.
The raw data file is 3.8GiB (including 8 billion uint32's)
the treated one is 5GiB (including 0.7 billion doubles)
Is there a way to get theese speeds the same?
I think lz4 compressing as I'm writing the files would solve the problem, But I don't know how to make matlab use lz4 commpresion while writing, as it's not documented on The h5write documentation site, any ideas? 
