This question is vague, but if you want to make the image with Javascript. It is simple.
function loadImages(src) {
if (document.images) {
img1 = new Image();
img1.src = src;
}
loadImages("image.jpg");
The image will be requested but until you show it it will never be displayed. great for pre loading images you expect to be requests but delaying it until the document is loaded.