What's the simplest and most robust way to have constant-height submit button with rounded corners?

Constant height so just left/right images should be necessary instead of having 4+, right? I'd still want top-to-bottom color gradient (and different one on hover).

If possible, I'd prefer 开发者_运维技巧if it was still an <input type='submit'> and not anything weird.

Is there any way (website / imagemagick script etc.) to generate these images automatically or do I need to draw them in some graphics program?

Here is a site that will let you create them: http://www.iwebtoolsonline.com/html-and-css-rounded-corner-button-generator