One way would be to use a latex to svg or latex to pdf tool and continue from that on a vector editing software, such as inkscape or adobe illustrator. That would keep it all as vector / text, which is great for publications.

Also, if you render it as a high DPI png and use normal image editing software, such as photoshop, you will still get pretty good results. The key here is that formulas are mostly all white with some black here and there, so it compresses really well, even for PNG. You won’t get a mega byte sized image.