Issue with some Aperio SVS files

[Benjamin Gilbert]

On 06/10/2014 03:13 AM, Benjamin Gilbert wrote:
> On your second slide, level 1 (4x downsample) has a bottom row which is
> missing every 4th tile.  On level 2 (16x downsample), only the first
> tile in the bottom row is missing, but the other tiles are corrupted.
> It seems that, when downsampling for level 2, the Aperio encoder chokes
> on the empty tiles it generated in level 1.  Tile (4, 5) in level 2
> should be composed of tiles (16, 20) through (19, 23) from level 1, but
> is actually composed of (13, 20) through (16, 23), *rotated right by one
> column*; and the missing tiles render as black when downsampled.

With Derek's permission, I've attached extracts from levels 1 and 2 that 
demonstrate this.  OPENSLIDE_DEBUG=tiles is enabled, and transparent 
pixels are shown in red.

--Benjamin Gilbert

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