ECW v4 support

Hi ​@hansh,

FME supports the latest ECW file format (v3) for reading and writing, and can both read and write transparencies in the ECW files.

If you have an ECW fie that is not being read properly, please attach a sample, and we will try to find why it is not being read correctly.

The documentation by Hexagon (the company that owns the ECW format) clarifies:

• The latest version of ECW is v3 
• There is also the ERDAS Software Development Kit (SDK), which is currently at version 6.1

So I expect there is some confusion between these version numbers.

(Edit below)

About the Alpha channel:

Opacity Channels
Opacity channels were introduced in version 4.1 of the SDK for ECW format, version 2 files. An opacity channel represents a “No Data” value for a particular pixel to indicate that the pixel should be either fully transparent or fully opaque (e.g. 0 or 255 for 8 bit data). Opacity channels are lossless and are usually stored as 1 bit (0 or 1). The work flow for compressing and decompressing ECW files with opacity is exactly the same
to that of JPEG 2000 for previously releases of the SDK.

(Source)

So transparency is possible since version 2 of the ECW format, and since version 4.1 of the SDK.

Thanks, that is the case, FME complains about the alpha band while saving to ECW for a file that was just transformed. We also tried saving to tif in ArcGIS and instead using that file to transform and then save back to ECW. I will check into the possibilities of sending the file. If so I’ll do that using the support channel.

If it’s the case that this already should work perhaps this thread should be deleted?

What is the warning/error message from FME?

ECW writer: This format does not support writing the RGB/RGBA bands in the raster with other extra bands. Please remove the extra bands and try again

How many bands do you have in the raster? Perhaps add a Logger before the writer and send the log file from a run.

It is a RGBA raster with 4 bands, I used RasterPropertyExtractor to find that out. When deleting the 4th band saving to ECW is possible. This is a drone orthophoto.

Can you supply a sample of the source image? I wonder if the band structure is being mis-interpreted within the workspace.

I have put the question to the responsible people if we can supply the image and are awaiting an answer.