Images are scaled up when using with imagemagick 6 (Ubuntu 14.04)

[JostBaron]

When I have defined this size

{
    name:   '1000',
    width:  3000,
    suffix: '-3x',
    upscale:false
}

an 800x600 image is upscaled to 3000x2250. My other options are:

options: {
    engine: 'im',
     quality: 70
}