Regarding aggregation at multiple levels

[Benjamin Gilbert]

On 11/07/2012 03:18 PM, Sriram Somanchi wrote:
> I understand that it might not have to do with OpenSlide library,
> however I want to understand how this aggregation is done. I tried this
> on the sample file that I have downloaded (CMU-1.svs) from openslide
> webpage and I get the following output.
>
> Like I said it might have to do with the library, however, it will be
> great if I can directed to documentation about this aggregation over
> multiple levels.

I'm not aware of any documentation on the scaling algorithms used by the 
various scanner software.  However, slide formats typically use lossy 
compression, so you may be seeing compression artifacts.

The value of the lower-resolution levels isn't their quality, it's the 
fact that they've been precomputed.  If you need to control the quality 
of the downsampling, you should regenerate the downsampled levels 
yourself, e.g. by using VIPS to create a pyramidal tiled TIFF from slide 
level 0.

--Benjamin Gilbert