In order to capture face images conveniently and efficiently, a special photographic room is setup in the Joint Research & Development Lab of Chinese Academy of Sciences. The space size of the room is about 4m*5m*3.5m. To capture faces with different poses, expression, accessories, and lighting, some special equipment are configured in the room including multiple digital cameras, all kinds of lamps, accessories (glasses, hats).
In our photographic room, a camera system consisting of nine digital cameras and a computer is elaborately designed. All the nine cameras are placed in a horizontal semicircular shelf with radius and height being 0.8 meters and 1.1 meters respectively. The type of the cameras is web-eye PC631 with 370,000 pixels CCD. They are all pointed to the center of the semicircular shelf and labeled as 0 to 8 from the subject’s right to left. The planform of the cameras distributed on the semicircle shelf is illustrated in following figure.
All of the nine cameras are connected to and controlled by the same computer through USB interface. The computer has been specially designed to support nine USB ports. We have designed software ourselves to control the nine cameras and capture images from them simultaneously in one shot. In each shot, the software can obtain nine images of the subject across different poses within no more than 2 seconds and store these images in the hard disk using a uniform naming conventions.
To cover varying lighting conditions, we setup a lighting system in our photographic room using multiple lamps and lanterns. To simulate the ambient illumination, two photographic sunlamps of high power covered with ground glass are used to mimic the indoor lighting environment. Actually, to obtain uniform lighting, they are arranged to irradiate to the matte white wall.
Then, some fluorescent lamps are coarsely arranged as “lighting sources” to form the varying lighting conditions. The lamps are configured in a spherical coordinate as shown in Figure 3, whose origin is the center of the circle, which coincided with the semicircular shelf. Fifteen fluorescent lamps are placed at the “lamp” positions as shown in the following figure, which are uniformly located at specific 5 azimuths (-90o, -45o, 0o, +45o, +90o) and 3 elevations (-45o, 0o, +45o). By turning on/off each lamp, different lighting conditions are simulated. In order to decrease the labor, currently, we are exploiting a multiplex switch circuit to control the on/off of these lamps. Note that, in all cases, the ambient lamps are kept on. And for the purpose of mimicking practicality simply, the flash systems like CMU or YALE are not exploited in our case. Therefore, these images with varying lighting conditions are recommended for the purpose of image processing and face recognition under natural illumination.
Accessories: Glasses and Caps
Several kinds of glasses and hats are prepared in the room used as accessories to further increase the diversity of the database. The glasses consisted of dark frame glasses, thin and white frame glasses, glasses without frame. The hats also have brims of different size and shape.
Without special statement, we are capturing face images with a blue cloth as the default background. However, in practical applications, many cameras are working under the auto-white balance mode, which may change the face appearance much. Therefore, it is necessary to mimic this situation in the database. In the current version of the CAS-PEAL, we just consider the cases when the background color has been changed. Concretely, five sheets of cloth with five different unicolors (blue, white, black, red and yellow) are used.
|CAP 2||CAP 3|
|GLASSES 1||GLASSES 2||GLASSES 3|
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For more information about the
CAS-PEAL face database,
please refer to our Technical Report on CAS-PEAL.