Thread: Help please on tile selection

Hi,
I am trying to "adjust" a big surface coverage mapset GARMIN IMG to an smaller surface. Windows 10.
Found two "easy" ways:
a) via MapInstall (use GMapTool to create installation, extract tiles to imgsupp.img via MapInstall to a virtual GPSr)
b) if edition is a must: via javawa device manager (create a virtual GPSr with the input.img, open it with javawa, see tiles map, note down ids of tiles, then open the needed tiles with MapEdit, save to mp, edit, recompile with mkgmap, etc.)

I searched north and south looking for a (free) tool for that ...

So, first question:
Is there any other tool available that could make life easier (ability to input IMG mapset directly, show a tile map, extract and compile the needed tiles into a img mapset) ?

In any case, I have an additional issue. I am using as input the OSM IMGs generated by ComputerTeddy. Issue is, those have a "short range" zoom (five levels, 0:24, 1:22, 2:20, 3:18, 4:17); Then, either MapInstall or javawa are uncomfortable to use: if zoom is far away such as have a "proper" 100 or 200 or 500kms perspective then tiles are shown just as empty rectangles (level 4) so there is no information to
decide what tiles to select. And, getting close enough one loses overall perspective, and, while information is shown for each tile, it is unclear what tiles to select. So, back and for zooming and unzooming... and prone to errors in the extraction, missing tiles needed or extracting tiles unneeded.

I searched again for a (free) tool or a procedure (IMG hex editing) that could solve this issue (even I do not fully understand the resolution/level thingy, I imagine that 4:17 could be "moved" to 8:9 and somehow so levels could be added in between 24 to 18 or added after 18...)

I was considering splitting the IMG, process the tiles with mp to change levels/resolution, remake IMG, but
there are over 140 tiles... and I do not know any command line tool able to process those mp files - could try to study further the mp internal structure of the mp and fiddle with a command line sed/grep/awk etc.
But looks even more work that zooming in and out.

Tried to understood if the TRE file could be modified to achieve the sought purpose but to no avail.

I also considered splitting and re-compiling using the --levels switch in mkgmap -> this could be the most promising path forward - would be nice if someone could confirm if this is viable

Not studies TYP yet... so perhaps it could be a way

So, second question:

Is it there any way to achieve that (tool, hex editing, --levels in mkgmap, ...).

Additional request...
Finally, I read in [Only registered and activated users can see links. ] that in the extinct yahoo forum for maps there was a tool to fiddle with resolution and levels - level editor. Nowhere in internet can I find it.
Anyone might have a copy lost in the fossil storage?

TIA
CT