function autoresizeimage(maxwidth,maxheight,objimg){
var img = new image();
img.src = objimg.src;
var hratio;
var wratio;
var ratio = 1;
var w = img.width;
var h = img.height;
wratio = maxwidth / w;
hratio = maxheight / h;
if (maxwidth ==0 && maxheight==0){
ratio = 1;
}else if (maxwidth==0){//
if (hratio<1) ratio = hratio;
}else if (maxheight==0){
if (wratio<1) ratio = wratio;
}else if (wratio<1 || hratio<1){
ratio = (wratio<=hratio?wratio:hratio);
}
if (ratio<1){
w = w * ratio;
h = h * ratio;
}
objimg.height = h;
objimg.width = w;
}