I have not tried downloading images, but I tried to download audio files and it worked for me.
Create a HTML page and put the link of the file in <a></a> tag.
So what do you need to do is serve the image as a attachment.
Just use <a href="yourdomain.com/getimage.php>get bg image</a> to initiate download as somnathbanik suggested.
When link is clicked a special page is shown inside browser telling you download details. After the user is done with save image flow, she/he can return to widget by pressing the back button.
header('HTTP/1.0 200 Ok');
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Expires: Sat, 26 Jul 1997 05:00:00 GMT"); //
header('Content-Disposition: attachment; filename="leaves.jpg"');
How to possible save image in phone memory in J2ME?.I am stuck this concept.Please help me..