Determining the actual scale factor ...

Jan Harkes jaharkes at
Wed Dec 1 10:43:12 EST 2010

On 12/01/2010 10:30 AM, Hauke Heibel wrote:

> I am wondering whether you know if there is a way to determine the
> actual scale at which an image was taken. It is not uncommon in
> microscopy applications to offer 1x 2x 5x ... 40x zoom settings
> corresponding the standard magnification lenses. In the MIRAX format
> there is a tag called OBJECTIVE_MAGNIFICATION which seems to state the
> zooming factor at which the zero-th pyramid level was acquired. This
> is quite nice since it would allow users to implement exactly the
> aforementioned functionality.
> I browsed a bit through the TIFF specs but did not find anything
> corresponding which were jumping right to my eyes. I am just asking
> since it makes very little sense for me to implement such a function
> for MIRAX only when there is no way to achieve the same with other
> image formats.
> So, in case anybody has an idea and is willing to share it, I would be
> happy to hear about it.

The following page seems relevant. It looks like Adam already tried to
identify possibly relevant properties in different slide formats
supported by openslide.


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