Put the NodataSetter after the Mosacker or at the very end.

Thanks for your reply and Sorry for this late reply. I had placed the RasterBandNoDataSetter (to have 0 values replaced) at the end of the workbench before the writer, it doesn't work. I've placed an extra RasterBandNoDataSetter (to have 255 values replaced), also it didn't work.

Any other methods I can tackle this in FME or perhaps there isn't one in FME?

Hello @messagemauri​ , would you be able to share your workspace and data? Here to help, Kailin.

Here is another idea. Try writing to another filetype. PNG supports transparency for example. Maybe yours doesn't.

Also, you can try clipping your raster to the the extent of your data. When writing, the outside should automatically receive a nodata flag.

Thank you very much @caracadrian​ and @kailinatsafe (Safer)​ 

I managed to get rid of the No Data 0 values (Black background) by actually implementing a PNGRASTER writer (Portable Network Graphics). However, there are a few black dots around the border of the image, refer to Actual Results below. I also placed the RasterBandNoDataSetter (to have 0 values replaced) at the end of the workbench but I get the same results. The output file is good, a lot better than before, but any ideas as to why there was some distortion that may have kept the black border dots (Band 0= 0, Band 1 = 0, Band 2 = 2) ??

Workbench:

Actual Results:

Compared to Previous Results the first time (undesirable results):

@kailinatsafe​  see, Sample Data zip File attached

@kailinatsafe (Safer)​  see sample Workbench attached.

Hello @messagemauri​ , sorry for the late response! I think I've managed to solve the issue. There was another challenge I ran into with the JPEG compression algorithm (leaves slight black areas around the mosaiced raster, but this is also fixable). If you would like to remove the remaining blackened areas, I recommend clipping your raster with a vector boundary (perhaps digitizing?), after the RasterInterpretationCoercer. Let me know if you have any questions about the attached workspace! Best of luck, Kailin.