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.



Even Rouault said...


Do you know through which channel the improvements have been submitted ? I see no evidence of a patch in GDAL Trac and can't remember an email on that subject on gdal-dev mailing list.


Paul said...

Hello Even,

I have send an email to the Perth team about the updates. They did mention Frank Warmerdam in my earlier conversation with them. In the past, we have worked directly with Frank before posting in GDAL.

Can you give me another day to track down the needed information to answer your question?


Even Rouault said...

The code improvements have now been submitted in GDAL trac :

Paul said...

Thanks Even!

Even Rouault said...

Just for clarity, in case that my previous comment was ambiguous. The code has been submitted for review & integration, but hasn't yet been integrated into GDAL mainline.

Apryll said...

Hey Paul - what pan-sharpening software does ERDAS currently like using the most? We have just made our pan sharpening software commercially available (formerly known as UNB Pansharp)...would be interested to learn more on your end.

Check us out at


Paul said...

Hello Apryll, ERDAS IMAGINE has all the most popular pan sharpening techniques, as well as techniques specifically requested by customers. We have about 7 techniques available at the IMAGINE Advantage level (I am guessing as I am at home without the software).

I have heard of UNB Pansharp out of the Univ of New Brunswick. It is a very good fusion technique.

If you would like to talk to Intergraph about a business relationship, please let me know how to contact you.