This paper presents our team’s (IDT-ITI-CERTH) proposed method for the Visual Sentiment Analysis task of the Mediaeval 2021 benchmarking activity. Visual sentiment analysis is a challenging task as it involves a high level of subjectivity. The most recent works are based on deep convolutional neural networks, and exploit transfer learning from other image classification tasks. However, transferring knowledge from tasks other than image classification has not been investigated in the literature. Motivated by this, in our approach we examine the potential of transferring knowledge from several pre-trained networks, some of which are out-of-domain. We concatenate these diverse feature vectors and construct an image representation that is used to train a classifier for each of the three subtasks of this Mediaeval task. Due to a bug in the original submission file, the official scores we got are 0.595, 0.479 and 0.380 for subtasks 1,2 and 3 respectively.