With an average resolution of 150dpi you get a picture of 11810 * 8269 pixels.
This resolution gives a decent result when printing.
You can increase the resolution and make tests.
The computation times are long but Gimp treats this image without problem. Here are the tests I made:
- Filter "Cubism".
- Save the image under a different name (format xcf.bz2), close this file and open the image.
- Filter "Mosaic".
- Save the image under a different name (format xcf.bz2), etc..
- At the end export to PNG, or any other format.
Tested with Gimp 2.8.0 64-bit Windows.
Test results :http://www.aljacom.com/~gimp/test_mosai ... saique.jpg
13,4 Mb (14 052 468 bytes)
Hugin is very good for stitch images if your camera's resolution is insufficient