Display image of fixed size using javascipt

I have some javascript as shown here: <script language="JavaScript" type="text/javascript"> scrnheight=[login to view URL]; picheight= [login to view URL](scrnheight * .4875* 1.3); picwidth = picheight * .5625* 1.3; var pic = "<div align='Left'><img id=picture alt='please wait ... picture is loading' " +" width=" + picwidth +"height =" + picheight +"</div>"; [login to view URL](pic); var pic1 = "<div align='Left'><img style=display:none id=pictureloading alt='please wait ... picture is loading' " +" width=" + picwidth +"height =" + picheight +"</div>"; [login to view URL](pic1); [login to view URL](); </script> What I want to do is to have the script changed so that it shows images in EXACTLY the same size as the actual image which is always 2.1 cms x 2.1 cms whatever the screen size and other differences (ie whether on a mobile, ipad, or big desktop screen etc). There are four instances where the same code is used and I would like the whole job done so that the code does what it did before but now shows images in this fixed size. You will have more opportunity to work on other aspects of the code after this initial project if all goes well. You must have your own webserver - I will not provide access to my server for your testing. Thanks Chris