Hi @limo​,

All raster datasets are naturally rectangular, so the black areas will always be included. However there are two ways to make them transparent in most image viewing tools:

• for single band datasets (ie. DEMs, monochrome images), a band value can be set to NoData. This works best for numeric datasets, since there is usually a wide range of rarely used values to choose from (ie. -9999). Monochrome imagery has a much smaller range (0-255), so usually 0 or 255 is chosen, and hopefully this doesn't catch any proper image values. You can use the RasterBandNodataSetter to set the NoData value before clipping. The Clipper will automatically assign outside pixels to the NoData value if it is set.
• For color or multi-band imagery you can get better results by adding an Alpha band to control transparency. The Clipper will automatically set the Alpha band to full transparent outside of the clip area. The easiest way to add the Alpha band is to use the RasterInterpretationCoercer to coerce from RGB24 to RGBA32, but you can also use the RasterBandAdder to add an Alpha band. This step must be done before clipping. Most image formats support Alpha, but one notable exception is JPEG. If you want transparent edges on an irregular dataset, I recommend saving as PNG or TIFF instead.

thanks @daveatsafe​ .

this is exactly what I was looking for.

It works good for me :)

I now get this result:

thanks a lot :)