def bandreduction(bands: List[VIPSImage],
reduction: ChannelReduction) -> VIPSImage:
if reduction == ChannelReduction.ADD:
return VIPSImage.sum(bands).cast(bands[0].format)
elif reduction == ChannelReduction.MAX:
return Operation.call('bandrank', bands, index=len(bands) - 1)
elif reduction == ChannelReduction.MIN:
return Operation.call('bandrank', bands, index=0)
elif reduction == ChannelReduction.MED:
return Operation.call('bandrank', bands, index=-1)
else:
raise ValueError(f"{reduction} not implemented")
def bandjoin(bands: List[VIPSImage]) -> VIPSImage:
if len(bands) == 1:
return bands[0]
return Operation.call('bandjoin', bands)