View source for ECW (file format)

{{Short description|File format for aerial photography}}
{{Infobox file format
| name                   = Enhanced Compression Wavelet
| icon                   =
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| caption                =
| extension              = .ecw
| mime                   =
| type code              =
| uniform type           =
| magic                  =
| owner                  = Hexagon Geospatial
| released               = 1998
| latest release version = ECW v3 - ECW/JP2 SDK v5.3
| latest release date    = June 14, 2016
| genre                  = [[Image file formats|Image file format]]
| container for          =
| contained by           =
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| url                    = http://www.hexagongeospatial.com/
}}
'''ECW''' ('''Enhanced Compression Wavelet''') is a [[proprietary software|proprietary]] [[wavelet compression]] [[Graphics file formats|image format]] used for [[aerial photography]] and [[satellite imagery]]. It was developed by Earth Resource Mapping, which is now owned by [[Intergraph]], part of [[Hexagon AB]].<ref>{{Cite web|last=Paul|date=2010-07-07|title=The Field Guide: Hexagon Acquires Intergraph|url=http://field-guide.blogspot.com/2010/07/hexagon-aquires-intergraph.html|access-date=2021-10-14|website=The Field Guide}}</ref> It is a [[lossy compression]] format for images.
In 1998 Earth Resource Mapping Ltd in [[Perth, Western Australia]] company founder Stuart Nixon (founder of [[Nearmap]]) and two software developers Simon Cope and Mark Sheridan were researching rapid delivery of terabyte sized images over the internet using inexpensive server technology. The outcome of that research was two products, Image Web Server (IWS) and ECW. ECW enables [[discrete wavelet transform]]s (DWT) and inverse-DWT operations to be performed quickly on large images while using a relatively small amount of memory.<ref>{{Cite web|title=Geospatial World – Top destination for geospatial industry trends|url=https://www.geospatialworld.net/|access-date=2021-10-14|website=Geospatial World|language=en-US}}</ref> Related (now expired) patents included {{Cite patent|country=US|number=6201897}} and {{Cite patent|country=US|number=6442298}} for ECW and {{Cite patent|country=US|number=6633688}} for IWS. These patents were obtained by ERDAS Inc. through the acquisition of Earth Resource Mapping on May 21, 2007.<ref>{{Cite web|url=http://field-guide.blogspot.com/2008/10/on-may-21-2007-erdas-announced-purchase.html|title=The Field Guide: ERDAS IMAGINE 9.3 and ER Mapper 7.2 now share licensing codes|date=October 8, 2008}}</ref><ref>{{Cite web|url=https://www.globenewswire.com/news-release/2007/05/21/97155/0/en/Hexagon-acquires-software-company-within-geospatial-imagery-segment.html|title=Hexagon acquires software company within geospatial imagery segment|first=Hexagon|last=AB|date=May 21, 2007|website=GlobeNewswire News Room}}</ref> Indirectly [[Hexagon AB]] became owner of these patents because they acquired [[Leica Geosystems]] in 2005 who had acquired ERDAS Inc in 2001.<ref>{{Cite web|url=https://leica-geosystems.com/about-us/summary/history|title=200 Years of Surveying History|website=leica-geosystems.com}}</ref>
After [[JPEG2000]] became an image standard, ER Mapper added tools to read and write JPEG2000 data into the ECW SDK to form the ECW JPEG2000 SDK. After subsequent purchase by ERDAS (themselves subsequently merged into Intergraph), the software development kit was renamed to the ERDAS ECW/JP2 SDK. [https://web.archive.org/web/20130923004151/http://geospatial.intergraph.com/products/other/ecw/ERDASECWJPEG2000SDK/Downloads.aspx v5] of the SDK was released on 2 July 2013.
== Properties ==
[[Map projection]] information can be embedded into the ECW file format to support [[geospatial]] applications.
Image data of up to 65,535 bands (layers or colors) can be compressed into the ECW v2 or v3 file format at a rate of over 25&nbsp;[[Megabyte|MB]]&nbsp;per&nbsp;second on an i7 740QM (4-cores) 1.731&nbsp;[[Gigahertz|GHz]] processor using v4.2 of the ECW/JP2 SDK. Data flow compression allows for compression of large images with small [[Random access memory|RAM]] requirements. The file format can achieve typical compression ratios from 1:2 to 1:100.
The ECW Protocol (ECWP) is an efficient streaming protocol used to transmit ECW and JPEG2000 images over networks, such as the Internet. ECWP supports ECWPS for private and secure encrypted streaming of image data over public networks such as the Internet.
There is a very fast read-only SDK supporting ECW and JPEG2000 which is available for no charge for desktop implementation for Windows, Linux and MacOSX.  A read / write SDK can be purchased for desktop and server implementations for Windows, Linux and MacOSX. A full functioning server implementation (using ECW, JPEG2000, ECWP and JPIP) was offered within the [https://web.archive.org/web/20151218190857/http://www.hexagongeospatial.com/en/products/provider-suite/erdas-ecw-jp2-sdk PROVIDER SUITE of the Power Portfolio] (formerly IWS) license.<ref>{{cite web |url=http://geospatial.intergraph.com/products/other/ecw/ecw/details.aspx |title=ERDAS Product Details: ECW |access-date=2013-03-11 |url-status=dead |archive-url=https://web.archive.org/web/20130315110011/http://geospatial.intergraph.com/products/other/ecw/ecw/details.aspx |archive-date=2013-03-15 }}</ref>
A previous version of the SDK (3.3) is available in open source, and can be used for non-Microsoft operating systems, such as Linux, macOS or Android.
== References ==
<references />
== External links ==
* [https://phowo.ifp.uni-stuttgart.de/publications/phowo01/Ueffing.pdf Ueffing – Wavelet based ECW image compression (PDF)]
* [http://geospatial.intergraph.com/Libraries/Brochures/ERDAS_ECW_JP2_SDK_Version_5_-_FAQ.sflb.ashx ERDAS ECW/JP2 SDK V5 FAQ (PDF)]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }}
{{Graphics file formats}}
{{DEFAULTSORT:Ecw (File Format)}}
[[Category:GIS raster file formats]]