function Week_FirstDay(FromDate){
 var TestDate = new Date()
 for (j=0; j<=7; j++){
  TestDate.setTime(FromDate.getTime()-(msc_day*j))
  if(TestDate.getDay() ==  1){return(TestDate)}
 }
}

var msc_day = 1000*60*60*24

function GetWeekNumber(FromDate){
 var tDate = new Date()
 tDate.setTime(FromDate.getTime())
 tDate = Week_FirstDay(tDate)
 for (w=0; w<53; w++){
  if (tDate.getFullYear() != FromDate.getFullYear()){return(w)}
  tDate.setTime(tDate.getTime()-(msc_day*7))
 }
}
now = new Date()
var image="week"+(GetWeekNumber(now)+1)+".jpg";
document.write("<IMG SRC='../images/week/"+image+"' BORDER=0 ALT='Photo de la semaine / Pic of the week'>");