tile_data column doesn't seem to be an image

[AndreMiras]

Isn't "tile_data" supposed to be jpg or png image?
Because when I dump it to a file it's not recognised as an image, but just "data".

This is the script I used for dumping:

#!/usr/bin/env python2
import sys
import sqlite3
import tempfile

database = sys.argv[1]
conn = sqlite3.connect(database)
c = conn.cursor()
c.execute("SELECT zoom_level, tile_column, tile_row, tile_data FROM tiles")
row = c.fetchone()
(zoom_level, tile_column, tile_row, tile_data) = row
# we're only interested in non-empty data
while len(tile_data) == 0:
    row = c.fetchone() # fetch next one
    (zoom_level, tile_column, tile_row, tile_data) = row
    # print "row(zoom_level, tile_column, tile_row, tile_data):", row
conn.close()
f = tempfile.NamedTemporaryFile(delete=False, suffix=".data")
f.write(tile_data)
f.close()
print "tile_data dumped to:", f.nam

Running the script:

$ ./dump_tile_data.py languedoc-rousillon.mbtiles 
tile_data dumped to: /tmp/tmpwJ1G_H.data
$ file /tmp/tmpwJ1G_H.data
/tmp/tmpwJ1G_H.data: data

However, when I try with another mbtiles which is not made from Tilemaker, the dumped data is actually a png:

$ ./dump_tile_data.py montpellier.mbtiles 
tile_data dumped to: /tmp/tmpyMet0n.data
$ file /tmp/tmpyMet0n.data
/tmp/tmpyMet0n.data: PNG image data, 256 x 256, 8-bit colormap, non-interlaced

Additional information:

• languedoc-rousillon.mbtiles was generated with Tilemaker (master branch 6a994ee) and "compress": false, the pbf was downloaded from Geofabrik
• montpellier.mbtiles was generated with makinacorpus/landez

[systemed]

It's meant to be a .pbf vector tile. Tilemaker makes vector tiles which you can use with an in-browser renderer, such as Mapbox GL, Tangram, or Leaflet.MapboxVectorTile; or you can use them as the foundation of a Mapnik-based rendering stack. It doesn't itself produce raster images like jpeg or png; if that's your aim you still need Mapnik or similar.

[AndreMiras]

Great, thank you for the hint!