How to convert ECW to GeoTIFF
You will need a desktop software to handle the conversion and one option is to use the free QGIS-program.
Download QGIS here: https://qgis.org/en/site/forusers/download.html
1. Open QGIS and add (e.g. drag-and-drop) your EWC file onto the map
2. From the top menu select Raster > Conversion > Translate (Convert format)
3. In the Translate-window select:
a) Input layer: Select your ecw-layer
b) Override the projection for the output file: choose a projection (optional! Needs to be projected, WGS84 will not work, but Web Mercator or other local projections will)
c) Assign a specified nodata value to output bands: If the background is black, select the nodata value to be 0
4. Additional creation options: Choose High Compression
5. Converted: Click on the (…) button and select Save to file
The delfalt format should be TIF files (.tiff).
6. Click Run. Conversion time might take minutes or even hours depending on the file size. Make sure you have enough space on your computer when handling large rasters.