Color-/Lineshifts under Windows?

[Hauke Heibel]

On Mon, Aug 9, 2010 at 5:52 PM, Adam Goode <agoode at andrew.cmu.edu> wrote:
> When it comes time to downsample the images, things get bizarre. To
> downsample, MIRAX concatenates 4 tiles together into 1 new JPEG tile.
> This is fine, except that it does this without stitching together the
> overlaps. So within a JPEG tile, you'll get overlaps. You can't treat
> the JPEG file as an atomic unit, instead you have to cut parts out of it
> and draw it just as you would the full sized tiles.

Ok, this is definitely "crazy". How did you find this out? Are there
indications in the Index.dat file leading to this conclusion? The
Slidedat.ini at least holds no clues for this.

Regarding the overlaps, you mention in the code that the MIRAX camera
takes a photo and splits that one into image_division^2 JPEG tiles. I
played with the split-mirax.py script and took a look at some pictures
and found some with no overlap, like these

Data0004_0000143002.jpg (left)
Data0004_0000143001.jpg (center)
Data0004_0000143000.jpg (right)

and some with a huge overlap like these

Data0004_0000142995.jpg (right)
Data0004_0000142996.jpg (right)

Am I hitting here such an example? Probably. What is interesting, is
that the latter pair of pictures requires horizontal and vertical
(~10px) shifting to be perfectly aligned.

Anyways, now I am confused, that it is possible to have a constant
tile shift for painting because some tiles do not overlap at all (at
least on the first levels until they are merged) and some others do.

I think in order to continue, I need to try to understand the
Index.dat file since I assume this is the file you mentioned earlier
where the tile positions are stored. That may take some time. ;)

So far, thanks for your answers!

Regards,
Hauke