Wednesday, September 19, 2012


The ERDAS ECW/JP2 SDK team in Perth Australia has done some work to update the ECW drivers in GDAL. These have been submitted to the GDAL community, and should make their way into a future version of GDAL.

There are multiple changes, but what I want to raise in this post, the performance of GDAL driver was improved in two main areas. While these bottlenecks were not in the ERDAS Desktop and Server product lines, we wanted to ensure our GDAL users had as similar a decoding performance as possible. 
  1.  GDAL 1.9 and earlier versions have a performance bottleneck when a single band is decoded line by line. This is not the preferred method of reading ECW data; nevertheless it is done by some folks. 
  2. GDAL 1.9 and earlier versions did not use the SDK’s implementation of supersampling, and GDAL’s own implementation was slower. Switching to supersampling using the SDK implementation halved time of the execution. 
While working on this small project, we did notice other areas where we can improve ECW support in the GDAL drivers going forward.

The Perth Team in Australia will improve the GDAL drivers more so when we upgrade GDAL to support the v5 of the SDK and the new ECW v3 file format early in the upcoming new year.

As has been policy, developer tools for decoding ECW and JP2 data using the SDK on desktop continue to be free.