I want to use this picture as the background of my website
Right now it is at 1040 x 660 and using JPEG compression at 70%. This seems to be same technique that Twitter is using for their homepage when you visit it signed out. This technique has gotten the image size down to about 180 KB which is acceptable to me. It's the same size as Twitter's.
However, I want to be able to provide even higher resolution versions of the image for high res screens such as my Macbook Pro Retina and iPad. I know I can do this with media queries but if the resolution goes up so does the size. Are there any compression technologies that would allow me to apply more or less compression to specific sections of an image? In this image, it would be idea to apply more compression to the out of focus sections behind the grill while leaving the asparagus and grill itself less compressed. Since the out of focus area is a large part of the image this should save a lot of space.