[gdal-dev] gdalwarp: mercator to lambert azimutal equeal area

[jumpjack]

Waht's wrong with this command?
gdalwarp -s_srs  "+proj=merc" -t_srs "+proj=laea" griglia.jpg  dest.jpg

Result:

ERROR 1: Unable to compute a transformation between pixel/line
and georeferenced coordinates for griglia.jpg.
There is no affine transformation and no GCPs.

How do I convert a mercator map to a Lambert Azimuthal Equal Area map?
How do I specifiy map edges?