This paper proposes a high-speed spectral imaging system using an active spectral illumination for solving several problems in the current spectral imaging and finding effective applications. Our synchronous imaging system is constructed by combining a high-speed spectral light source and a high-speed monochrome camera. We describe the principle of illuminant control. Spectral-power distributions are generated as a time sequence. Then, we show some effective applications in the field of color imaging science and technology, which are (1) a quick estimation of surface-spectral reflectances, (2) a new method for colorimetry, and (3) a visual evaluation system under arbitrary illuminants, using the constructed imaging system. We demonstrate the usefulness of the proposed imaging system and the feasibility of the new technology for color imaging.