Abstract: A mobile device testing system with a sphere assembly is disclosed. The sphere assembly is a source integrating sphere and a test integrating sphere connected by an optical channel. A source illuminates the source integrating sphere with electromagnetic radiation of a known spectrum of wavelengths, usually light. The electromagnetic radiation travels to the test integration sphere through the optical channel. A first filter assembly and/or a second filter assembly rotate a plurality of filters into the optical channel to change the spectral distribution of wavelengths of the electromagnetic radiation in the test integrating sphere. A mobile device is mounted to the test integrating sphere and the spectral distribution of an image acquired by the mobile device is compared to a spectral measurement from a spectrometer.