Map Calibration, projection problem

[bnv]

Hi all,



I have a simple map of France where all longitudes are parallel and perpendicular to latitudes,

generated by a plotting program like an X-Y plot.

The distance between longtitudes is always constant every 1deg is few houndreds of pixels

as well the distance between latitudes is always constant.

I've tried to calibrate it with the following projections but both are failing

- Flat earth: rotates the map, all four corners have wrong coordinates

- Latitude/Longitude: the corners have the correct coordinates (long+lat),

   all other longitudes are ok but the latitudes in the middle of the map are

   shifted vertically downwards by a non constant amount (max in the middle

   about 0.3deg)



Which projection should I use?



Thanks in advance

V.

[bnv]

Any reply?