Raster Bands

If the raster is a colour raster, i.e. an image, it should have 3 bands displaying the RGB values;
If the raster is a numerical raster, e.g. a DTM, it should have 1 band displaying the numerical value.

To remove any unwanted bands (e.g. alpha band), use the RasterSelector transformer followed by the RasterBandKeeper or RasterBandRemover transformer.

To separate the RGB bands, use the RasterBandSeparator transformer.