It discusses a new method of the description about the luminous intensity distribution of spotlight. An image with 256-brightness-grades on a plane which is perpendicular to spotlight's main axis is created

from which the lighting direction and intensity can be calculated by each pixel's brightness and location. By this way

the luminous intensity data of luminaries or lights can be accessed

stored or calculated easily

and the expression for unsymmetry-luminous-distributed spotlights is more accurate. This method may take an important role in the simulation and visualization of lighting environment. Using a picture of brightness to express the LID of the spotlight is correspond to put infinite curves from all the connected planes in range of 360 degree surrounding the main light axis to a picture and display it directly. It is especially convenient to the LID-adjustable spotlight used for TV and movie. A system is developed using a set of camera and white diffuse reflection wall to take the lighting picture from which the luminous intensity distribution image can be created after being processed according to the camera exposure latitude. Example pictures of lighting scenes using the distribution images are given.