The tiles can be saved in
the listed formats with the specified options.
- JPEG:
JPEG is the graphics format used most in the web for photos. The JPEG
format is based on a lossy compression algorithm. JPEG is especially
recommended if your map contains many colors (e.g. satellite images)
The number in the entry box represents the used quality, a higher
quality meaning bigger files and therefore longer loading times for the
user. Visually loss-free images are to be expected up to a compression
rate of 15 (quality factor 85). Reasonable values with good results vary between
70 and 95.
- PNG:
This loss-free format is recommended if you have got many fine objects in
your map. The selection box offers the possibility to choose between “PNG
24” and “PNG 32”, the latter containing an additional channel for
transparency. The PNG format accomplishes better compression rates than
the JPEG format in images with big, monochrome areas, but is clearly
inferior to the latter when it comes to photos.
- GIF:
This somewhat aged graphics format can only save 256 different colors. If
your map has few colors, you can select this format. But most of the time
the other formats are preferable.
- TIFF:
This format is only available for the tile export.
You can create compressed, completely loss-free tiles with it, if you
prefer working with TIFF instead of PNG files.
Please note that this is a so-called “Baseline TIFF” and not a
“GeoTIFF" with integrated geo referencing.