A system for generating a confidence value for at least one predetermined state in the interior of a vehicle, comprising: an imaging unit configured to capture at least one image of the interior of the vehicle, and a processing unit comprising a convolutional neural network, wherein the processing unit is configured to receive the at least one image from the imaging unit and to input the at least one image into the convolutional neural network, wherein the convolutional neural network is configured to generate a respective likelihood value for each of a plurality of predetermined states in the interior of the vehicle with the likelihood value for a respective state indicating the likelihood that the respective state is present in the interior of the vehicle, wherein the processing unit is further configured to generate a confidence value for at least one of the plurality of predetermined states in the interior of the vehicle from the likelihood values generated by the convolutional neural network, characterized in that: - the predetermined states are arranged in a hierarchical tree structure including a plurality of hierarchical levels; and wherein the processing unit is configured to generate the confidence value for a respective one of the plurality of predetermined states in the interior of the vehicle by multiplying the likelihood value for the respective state by the likelihood values of all ancestors of the respective state in the hierarchical tree structure. an imaging unit configured to capture at least one image of the interior of the vehicle, and a processing unit comprising a convolutional neural network, wherein the processing unit is configured to receive the at least one image from the imaging unit and to input the at least one image into the convolutional neural network, wherein the convolutional neural network is configured to generate a respective likelihood value for each of a plurality of predetermined states in the interior of the vehicle with the likelihood value for a respective state indicating the likelihood that the respective state is present in the interior of the vehicle, wherein the processing unit is further configured to generate a confidence value for at least one of the plurality of predetermined states in the interior of the vehicle from the likelihood values generated by the convolutional neural network, characterized in that: - the predetermined states are arranged in a hierarchical tree structure including a plurality of hierarchical levels; and wherein the processing unit is configured to generate the confidence value for a respective one of the plurality of predetermined states in the interior of the vehicle by multiplying the likelihood value for the respective state by the likelihood values of all ancestors of the respective state in the hierarchical tree structure. - the predetermined states are arranged in a hierarchical tree structure including a plurality of hierarchical levels; and wherein the processing unit is configured to generate the confidence value for a respective one of the plurality of predetermined states in the interior of the vehicle by multiplying the likelihood value for the respective state by the likelihood values of all ancestors of the respective state in the hierarchical tree structure.