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Fix seams in Trestle #21
_This comment originally by _agoode* at 2010-01-14T21:21:09Z.*
Aha! There are some auxiliary files that end in ".tif-0b", ".tif-1b", ".tif-2b". These are as-yet undecoded but the file sizes are proportional (factor 4x) and the Trestle viewer shows seams when they are removed.
It looks like openslide-vendor-trestle.c has it covered. There is an EXIF tag called trestle.OverlapsXY which specifies the total pixel overlap in both axes. The total pixels are helpfully divisible by this number! Stitched images based on this and using openslide-write-png look good - same slight stitch imperfactions I see in the trestle viewer. Still no idea what is actually in those tif-0/1/2b metadata files. Thanks!
A good alignment along a row of tiles can be produced by computing tile coordinates as:
Likewise, along a column of tiles:
But the tile coordinates produced by these two calculations can be significantly different. To use the position data effectively, it appears we would need to use the
As in MIRAX, photos are split into multiple tiles (4 x 4). Unlike in MIRAX, the standard overlaps are applied to all tiles from a single photo, though there are no individualized overlaps within a photo. So, within a given photo:
Also unlike MIRAX, levels which combine multiple photos into each tile have no overlaps. This explains why there are only overlaps for the first three levels.