Minor Downsampling bug? [Aperio svs images]

Benjamin Gilbert bgilbert at cs.cmu.edu
Mon Jan 11 12:12:11 EST 2016

Hi Derek,

On Mon, Jan 11, 2016 at 12:52:36PM +0000, Derek Magee via openslide-users wrote:
> I think I've just discovered a minor (but quite annoying, if you are doing
> image analysis) bug in OpenSlide.  When you request two overlapping
> sub-regions of arbitrary offet using openslide_read_region() the values
> you get back are similar at the same global location, but can differ by
> (it seems) up to 1 value in each channel.  While you can't tell the
> difference looking at the image, this can be annoying when doing image
> analysis on overlapping tiles.  I've observed this at a non-native
> downsample level (I can't tell if it occurs at level 0).

Thanks for the report.  This is probably the same issue:


I haven't tracked this down, but I suspect the cause may be Aperio's
non-integer downsamples.  Are you able to reproduce this with other file

--Benjamin Gilbert

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