Qlikview Maps

[geogou1973]

Hello

I have the following script in a qvw application

// Google Maps Key
// get a key here http://code.google.com/apis/maps/signup.html
// gmap_key = '';
max_zoom_level = 17; //maximum value 17

// Variables required for calculating map
// No need to change these
var_pi180=      '=pi()/180';
var_lat_offset= '0';
var_mc2=        '=256*pow(2,$(var_zoom))';
var_mc1=        '=256*pow(2,($(var_zoom)-1))';
var_mid_lat=    '=min(Latitude)+(1+var_lat_offset)*((max(Latitude)-min(Latitude))/2)';
var_mid_long=   '=min(Longitude)+(max(Longitude)-min(Longitude))/2';
var_zoom=       '=max(aggr(if(max( round(256*pow(2,(_zoom_level -1)))+( Longitude *((256*pow(2,_zoom_level ))/360)) )-min( round(256*pow(2,(_zoom_level -1)))+( Longitude *((256*pow(2,_zoom_level ))/360)) ) <map_size_x AND max((256*pow(2,(_zoom_level-1)))+((0.5*log((1+(sin((Latitude)*pi()/180)))/(1-(sin((Latitude)*pi()/180)))))*((-256*pow(2,_zoom_level))/(2*pi()))))-min((256*pow(2,(_zoom_level-1)))+((0.5*log((1+(sin((Latitude)*pi()/180)))/(1-(sin((Latitude)*pi()/180)))))*((-256*pow(2,_zoom_level))/(2*pi()))))<map_size_y,_zoom_level,1),_zoom_level))';
var_maptype=    '=if(isnull(only(maptype)),fieldvalue( '&chr(39)&'maptype'&chr(39)&', 1 ),maptype)';
map_size_x= '640';
map_size_y= '400';

SET HidePrefix='_' ;
// Field required for calcualting best zoom level
_zoom_level:
Load RecNo( ) as _zoom_level autogenerate(max_zoom_level);

maptype:
LOAD * INLINE [
maptype
roadmap
mobile
satellite
terrain
hybrid
];

set hideprefix = 'maptype';

it works perfect but i want to decrease the area.

For this reason i change the following 

map_size_x= '350';
map_size_y= '250';

it works also and it decreases the area but the letters of the cities and countries is not so clear as before when

x='640' and

y='400'

Do i have to change anything else in order to have as clear as before letters in the map ?

Thank you in advance