ECW (Enhanced Compression Wavelet) is a proprietary

wavelet compression In mathematics, a wavelet series is a representation of a square-integrable (real- or complex-valued) function by a certain orthonormal series generated by a wavelet. This article provides a formal, mathematical definition of an orthonormal w ...

image format An Image file format is a file format for a digital image. There are many formats that can be used, such as JPEG, PNG, and GIF. Most formats up until 2022 were for storing 2D images, not 3D ones. The data stored in an image file format may be ...

used for

aerial photography Aerial photography (or airborne imagery) is the taking of photographs from an aircraft or other airborne platforms. When taking motion pictures, it is also known as aerial videography. Platforms for aerial photography include fixed-wing aircr ...

and satellite imagery. It was developed by Earth Resource Mapping, which is now owned by

Intergraph Intergraph Corporation was an American software development and services company, which now forms part of Hexagon AB. It provides enterprise engineering and geospatially powered software to businesses, governments, and organizations around the w ...

, part of

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. It is a

lossy compression In information technology, lossy compression or irreversible compression is the class of data compression methods that uses inexact approximations and partial data discarding to represent the content. These techniques are used to reduce data size ...

format for images. In 1998 Earth Resource Mapping Ltd in

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company founder Stuart Nixon (founder of

Nearmap Nearmap (officially Nearmap Pty Ltd) is an aerial technology company headquartered in Australia that provides frequently-updated, high-resolution aerial imagery and location intelligence on up to 91% of Australia's population, 80% of the United S ...

) 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 In numerical analysis and functional analysis, a discrete wavelet transform (DWT) is any wavelet transform for which the wavelets are discretely sampled. As with other wavelet transforms, a key advantage it has over Fourier transforms is temporal ...

s (DWT) and inverse-DWT operations to be performed quickly on large images while using a relatively small amount of memory. Related (now expired) patents included and for ECW and for IWS. These patents were obtained by ERDAS Inc. through the acquisition of Earth Resource Mapping on May 21, 2007. Indirectly

became owner of these patents because they acquired

Leica Geosystems Leica Geosystems (formerly known as Wild Heerbrugg or just Wild) based in eastern Switzerland produces products and systems for surveying and geographical measurement (geomatics). Its products employ a variety of technologies including GPS sa ...

in 2005 who had acquired ERDAS Inc in 2001. After

JPEG2000 JPEG 2000 (JP2) is an image compression standard and coding system. It was developed from 1997 to 2000 by a Joint Photographic Experts Group committee chaired by Touradj Ebrahimi (later the JPEG president), with the intention of superseding thei ...

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
v5
of the SDK was released on 2 July 2013.

Properties

Map projection In cartography, map projection is the term used to describe a broad set of transformations employed to represent the two-dimensional curved surface of a globe on a plane. In a map projection, coordinates, often expressed as latitude and longit ...

information can be embedded into the ECW file format to support

geospatial Geographic data and information is defined in the ISO/TC 211 series of standards as data and information having an implicit or explicit association with a location relative to Earth (a geographic location or geographic position). It is also ca ...

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 MB per second on an i7 740QM (4-cores) 1.731 GHz processor using v4.2 of the ECW/JP2 SDK. Data flow compression allows for compression of large images with small

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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 th
PROVIDER SUITE of the Power Portfolio
(formerly IWS) license. 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

External links

Ueffing – Wavelet based ECW image compression (PDF)

ERDAS ECW/JP2 SDK V5 FAQ (PDF)
{{DEFAULTSORT:Ecw (File Format) GIS raster file formats