JPEG Editor

I am making some sprites for a game I'm developing. I've been using Paint so far to create the images, however I'm finding that sometimes paint decides to 'compress' the image while I'm working with it, causing artifacting. I need the images in JPEG format, and I need the pixels to stay at PRECISELY the values I set for them.

What JPEG editor should I use?

>>1
JPEG needs to be re-encoded every time you save. Not technically, some affine transforms can be done without a need to re-encode but I have yet to find any software that will actually bother checking for this