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Thumbnail/overview production speed #14

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
Histogram statistics for overview image stretch may be generated from 
subsample image rather than original scene at full resolution to increase 
throughput.

Create overview image without stretch (scale image values to 8bit to 
retain dynamic range)
Calculate values for histogram on overview
Generate overview and thumbnail

Original issue reported on code.google.com by simonaol...@gmail.com on 21 Feb 2010 at 10:30

GoogleCodeExporter commented 9 years ago 
[deleted comment]
GoogleCodeExporter commented 9 years ago 
Overview generation time reduced by 2/3 by using approximate statistics - the
bApproxOk flag in GDALRasterband.GetStatistics() and 
GDALRasterband.GetHistogram(). 
This has a minor impact on image quality generally, however I do remember 
setting
bApproxOk=0 for a reason. There was a certain image that gdal returned garbage 
stats
for when bApproxOk=1 but expected stats when bApproxOk=0. I'll have a look back 
thru
the revisions to see if I can find it.

Original comment by pinner.luke@gmail.com on 3 Mar 2010 at 11:47

GoogleCodeExporter commented 9 years ago 
This issue was closed by revision r212.

Original comment by pinner.luke@gmail.com on 3 Mar 2010 at 11:47