Question: how is a region extracted?

PD Dr. M. Weihrauch m.weihrauch at
Thu Aug 31 05:24:20 EDT 2017

Dear John:
Thanks for the information!

@Benjamin: Would you consider to integrate the SZI format into
OpenSlide? I have all the technical specifications as well as some
simple libraries / functions to quickly access slides from it.

Currently, SZI is being integrated by:
- EasyScan (
- Uscope scanners

I know of other vendors, which collaborate with us that they also want
to support it as it is simple and straight forward and great for serving
tiles from a single file format.

Best regards


Am 30.08.2017 um 23:50 schrieb jcupitt at
> Hi Martin,
> On 30 August 2017 at 19:49, PD Dr. M. Weihrauch
> <m.weihrauch at> wrote:
>> If you extract a certain region from a zoom level via OpenSlide, how
>> does OpenSlide do that?
> It varies with the image format. For most of them, the file contains
> raw images from the camera, plus some metadata saying how they should
> be pasted together (position, rotation, scale, opacity). To render a
> region of the output image, openslide decompresses all images which
> touch that region, then blends them together to the output using
> Cairo.
> They also usually contain extra levels for zooming out, plus sets of
> extra images for things like barcodes.
> SZI should be a lot simpler since you have constant overlaps and positions.
> John

Priv.-Doz. Dr. med. Martin Weihrauch
Facharzt für Innere Medizin,
Hämatologie und intern. Onkologie
Smart In Media GmbH & Co. KG
Intelligent Software

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