Re: [Openexr-devel] Adding/updating attribute to existing OpenEXR file

[Florian Kainz]

The attributes in an OpenEXR file are tightly packed.  Any edit
that adds or removes an attribute or that changes the size of
an attribute requires copying the file.  In principle changing
the value of an attribute without changing its size can be done
in place, but the IlmImf library does not currently support this.

The copyPixels() operation in Ken's example is pretty fast because
it directly copies the pixels in compressed form without expanding
and recompressing the data.

Florian