6. Face temperature differences after alcohol consumption

The thermal differences between various locations on the face are examined in this section [2]. The purpose of this approach is to examine specific locations on the face and find out if the temperature difference between these regions changes with alcohol consumption. Thus we are not interested for the temperature of the eye but if its temperature changes with respect to another location of the face, for example, the lips. In order to apply this procedure, the image of the face of each person was partitioned into a matrix of 8 � 5 squared regions of 10 � 10 pixels each. The position of the regions was exactly the same for a specific person (sober and drunk). The temperature difference of all possible pairs of squared regions is monitored as the person consumes alcohol. A total of 40 values were calculated on the face of a specific person who correspond to the squared regions for a specific acquisition.

The thermal differences among all values of the 40 squared regions were evaluated, thus creating a matrix 40 40. We had to compare the difference matrices which correspond to the same person when he was sober and in the case he consumed alcohol (Figure 4). The maximum variation between the corresponding differences is monitored and actually reveals the regions which change temperature with alcohol consumption. It was found that for the drunk person the nose and mouth has increased temperature in relation to the forehead.

The main finding of this approach is that two locations, as shown in Figure 3, are good candidates for proving intoxication, namely the forehead and the nose. For the drunk person,

the forehead appears cooler than the nose while for the sober, the two region are at the same temperature. Figure 4a is presented with the thermal difference matrix for the sober person. In Figure 4b, the thermal difference matrix for the drunk person is shown. These two matrices differ significantly on the white locations of matrix Figure 4(c). The final matrix which is the difference of the difference matrices is crucial for revealing locations of the face with large

Figure 5. The black regions on faces A and B are those presenting maximum difference with alcohol consumption. These

Intoxication Identification Using Thermal Imaging http://dx.doi.org/10.5772/intechopen.72128 155

In Figure 5 demonstration of the described method is given. The black regions on the face are those presenting maximum difference with alcohol consumption. These regions were indicated by the difference of the difference matrices. Accordingly, if the nose of a person is hotter than the

In this section, blood vessels are separated and isolated from the rest of the information on the image of the face by applying morphology on the diffused image. For this purpose, the top-hat transformation is applied [7]. Top-hat transformation is applied to isolate hot or cold features in an image of a specific size. An example is shown in Figure 6. The features to be isolated are

The basic morphological operation is that of erosion [26, 27]. Erosion is a shrinking procedure carried out when a signal A (binary or gray scale) is affected by another signal S, the structur-

A ⊖ S ¼ f g ð Þ i; j ∈ A : S ið Þ ; j ⊂ A (11)

forehead, this person should be declared as intoxicated by a drunk identification system.

7. Face blood vessels activity in drunk person

regions were indicated by the difference of the difference matrices.

of 5 � 5 pixels area. This transformation is described next.

where ð Þ i; j is the position of A on which S lies.

temperature variation.

7.1. Top-hat transformation

ing element:

Figure 3. Each of the black regions is of 10 10 pixels area. A total of 8 5 regions are taken on each face. The temperature difference between the regions is monitored as the person consumes alcohol.

Figure 4. Three difference matrices, (a) for the sober person and (b) for the drunk person, (c) the difference of the difference matrices (values normalized to full grayscale). Large changes for the thermal differences on the face are indicated by white points on this matrix. The white circle corresponds to the largest difference equal to 29.8.

Figure 5. The black regions on faces A and B are those presenting maximum difference with alcohol consumption. These regions were indicated by the difference of the difference matrices.

the forehead appears cooler than the nose while for the sober, the two region are at the same temperature. Figure 4a is presented with the thermal difference matrix for the sober person. In Figure 4b, the thermal difference matrix for the drunk person is shown. These two matrices differ significantly on the white locations of matrix Figure 4(c). The final matrix which is the difference of the difference matrices is crucial for revealing locations of the face with large temperature variation.

In Figure 5 demonstration of the described method is given. The black regions on the face are those presenting maximum difference with alcohol consumption. These regions were indicated by the difference of the difference matrices. Accordingly, if the nose of a person is hotter than the forehead, this person should be declared as intoxicated by a drunk identification system.
