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 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