1. A regulated amount measuring apparatus comprising: a colorimetry section that measures colors; a first storage section that stores a color profile associating coordinate values on a colorimetry color space representative of colorimetry values obtained through the colorimetry section with coordinate values on a device color space, wherein a plurality of primary colors adopted in an image output device is established as a coordinate axis; a conversion section that converts the colorimetry values obtained through the colorimetry section into the coordinate values on a device color space via the color profile; a computing section that computes differences between two sets of coordinate values on the device color space, which are obtained through conversion by the conversion section of two sets of colorimetry values obtained through twice colorimetry by the colorimetry section; and a display section that displays the differences computed by the computing section.