1.  Field of the Invention
The present invention relates to a projection apparatus, projection method, and storage medium having program stored thereon program, suitable for a projector or the like of, for example, the digital light processing (DLP) (registered trademark) system. 
2.  Description of the Related Art
In recent years, projectors of the DLP (registered trademark) system are becoming widespread. 
In a projector of the DLP (registered trademark) system, a micromirror element forms an optical image by the overall pixels by a modulating operation of reflecting light from a projection light source in the direction of the projection optical system for a time width corresponding to the gradation for each pixel position. 
The light component which has not been reflected in the direction of the projection optical system, so-called off light is applied to a nonreflecting part set in advance to be converted into heat, and is finally discharged to the outside of the housing. 
As described above, in the projector of the DLP (registered trademark) system, how efficiently discharge the heat attributable to the off light, and filling the inside to the outside leads to a stable projection operation, and hence various proposals are made in this regard. ( for example, Jpn.  Pat.  Appln.  KOKAI Publication No.  2008-292953)
Incidentally, in the field of television or video, a technique of displaying a three-dimensional image has been put to practical use, and two or three three-dimensional projection systems are investigated also regarding the projector. 
Among these, as one of the systems in which an image for the left eye, and image for the right eye are alternately projected by using 3D liquid crystal glasses, a technique of providing a field period in which a synchronization pulse of, for example, white color having higher illuminance is projected during an extremely-short time which is not perceptible to the naked eye, in a synchronization signal for switching between right-eye image projection and left-eye image projection separately from a field period in which an image of each of colors of red, green, and blue is projected, is considered. 
In this technique, during the field period including the synchronization pulse, and liquid crystal response time subsequent thereto, all the brighter white light is disposed of as off light other than the timing at which the pulse is projected. 
Accordingly, almost all the light brighter than that at the time of normal optical image formation is disposed of as off light, and hence the amount of heat to be discharged as a result is great, whereby there is a problem that the heat radiation unit is inevitably made larger.