new Image().src='c:\file.jpg' does not work under firefox?

I want to get the width/heigh value of picture

[iProgram]

I have a web form which lets visitor to upload picture to my server. The requirement is all these pictures should be 80x80 px. I use the following method to check image size:

<input onchange="check(this)" type="file" />
function check(f)
{
var img = new Image();
img.src = f.value;
alert(img.width + ' x ' + img.height);
}

It works under IE but Firefox/Opera alert "0 x 0". Please help.

[DrDoc]

That is a safety measure. You do not have direct access to file objects on the remote system. Unfortunately, IE gives you that access.

[iProgram]

So no way?

[garyr_h]

You could try using an alternative language like PHP and use the getimagesize() function which will do what you want.

[kaled]

Does it work if the image is rendered in the page (rather than simply using an abstract object)?

Kaled.

[Bernard Marx]

No. In FF, an image src can't be set to a path within the filesystem by a page on a server (I tried. The JS console said something along those lines).