[OSM-dev] speeding up tile rendering using a custom "convert -color 255" program.

Jon Burgess jburgess at uklinux.net
Thu Nov 23 02:22:55 GMT 2006

While experimenting with the new tile renderer I noticed that the
"convert -color 255" step of the tile generation was taking more CPU
than anything else. To attempt to optimise this I hacked together a
quick C program which uses the same ImageMagick library but with
hardcoded options. For me this is several times faster than the stock
convert command. 

I don't know the complete story behind why this custom version is so
much faster. Perhaps it is because I've not provided any colour space
correction or dithering parameters. Maybe i've lost some quality in the
output, but the tiles I've generated with it so far look OK to me.

Let me know if you want this added to SVN (i'm thinking maybe a subdir
of utils/mapnik). Or perhaps you can come up with some options on
convert which will make it just as quick. 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: Makefile
Type: text/x-makefile
Size: 202 bytes
Desc: not available
URL: <http://lists.openstreetmap.org/pipermail/dev/attachments/20061123/4484cad3/attachment.bin>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: color255.c
Type: text/x-csrc
Size: 1516 bytes
Desc: not available
URL: <http://lists.openstreetmap.org/pipermail/dev/attachments/20061123/4484cad3/attachment.c>

More information about the dev mailing list