Hi all,
What is the relationship between the "PER_DATASET_ALPHA" mask of the RGB
bands in a raster dataset, and the Alpha Channel? I created a four-band
tiff file with gdalwarp from an RGB original. On creation, the fourth
band has all values set to 255, and the whole picture is visible.
However, when setting parts of the fourth band to zero with
gdal_rasterize, everything remains visible. Could that be caused by the
Mask Flags of the first three channels, and, if so, what can I do about it?
Band 1 Block=4016x1 Type=Byte, ColorInterp=Red
Mask Flags: PER_DATASET ALPHA
Band 2 Block=4016x1 Type=Byte, ColorInterp=Green
Mask Flags: PER_DATASET ALPHA
Band 3 Block=4016x1 Type=Byte, ColorInterp=Blue
Mask Flags: PER_DATASET ALPHA
Band 4 Block=4016x1 Type=Byte, ColorInterp=Alpha
Jan
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