def from_gdal_dataset(cls, dataset, band):
"""
Creates a new 1-band VImage from `dataset` at `band`
dataset: GDAL Dataset
band: Number of the band, starting from 1
"""
with LibVips.disable_warnings():
filename = dataset.GetFileList()[0]
image1 = VImage(filename)
# Extract the band
image2 = image1.extract_bands(band=(band - 1), nbands=1)
# Cast to the right datatype, if necessary
datatype = dataset.GetRasterBand(band).NumPyDataType
if image2.NumPyType == datatype:
return image2
types = dict((v, k) for k, v in cls.NUMPY_TYPES.iteritems())
image3 = VImage.frombuffer(
image2.tobuffer(), width=image2.Xsize(), height=image2.Ysize(), bands=1, format=types[datatype]
)
image3._buf = image2
return image3
