Documentation was already clear on this only stripping GPS tags.
But there are more potentially sensitive metadata tags (e.g. author
and possibly description) and the name alone suggests a broader effect.
Thus change the filter to strip all metadata except for colourspace info
and orientation (technically it strips everything and then readds
selected tags).
Explicitly stripping CommonIFD0 is needed since -all does not modify
IFD0 due to TIFF storing some actual image data there. CommonIFD0 then
strips a bunch of commonly used actual metadata tags from IFD0, to my
understanding leaving TIFF image data and custom metadata tags intact.
Oneric
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