# Automatic TV Logo Identification for Advertisement Detection without Prior Data
## 3 Dataset Description
Given the many different possible characteristics that channel logos can assume (e.g., transparencies, animations, position, and size), in Table 3 we provide further detail on the characteristics of the gathered dataset with regards to the channel logo. Although channel logos have some similar characteristics, significant differences are also noticeable, including size, shape, and color. Even in the same channel it is possible to observe the usage of different logos in distinct points in time or a periodic switching between logos. These many possible variations augment the difficulty of automatic logo detection. For instance, the RTP1a and RTP2 streams have a monochromatic logo that is absorbed or becomes partially invisible in multiple situations, as illustrated in Figure 1. As an additional example, let us consider the RTP1b and Eurosport streams. The first contains mostly news content, with an almost permanent crawler and other on screen objects, making it extremely difficult to just use temporal consistency information. Additionally, the channel logo varies between the generic RTP1 logo and a special 60 years anniversary logo through random transitions, as seen in Figure 2. The Eurosport stream contains mostly sports content and uses a transparent channel logo. Consequently, the logo blends with the background making its detection harder, as depicted in Figure 3.  
The collected dataset also encompasses situations of self-advertising. These are very complex situations that hinder the frame classification process. The RTP2 and TVI streams have announcements of upcoming programs which contain a grayed version of the channel logo. Examples of these situations can be seen in Figure 4.  
An important aspect that must be highlighted is that, even in the 8 h streams, there are multiple advertisements that appear only once. This indicates the unsuitability of using advertisement detectors based on finding repetitions. A closer look at the dataset shows that there are 978 individual segments with an average time per segment of approximately 26 s; the larger observed segment is 1 min and 10 s long. The advertisements always appear grouped into blocks with a varying number of segments and duration. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Features** & **Program** & **Advertisement** \\  & **Content (\%)** & **Content (\%)** \\ \hline Channel Logo & 97.9\% & 3.1\% \\ Crawler & 36.2\% & 4.1\% \\ Sign Language & 14.7\% & 1.7\% \\ Subtitles & 34.9\% & 3.0\% \\ Other Logos & 40.5\% & 23.5\% \\ Transition Silences & 57.2\% & 86.4\% \\ Dialog & 92.4\% & 25.2\% \\ Background Music & 70.0\% & 93.3\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Temporal distribution of the presence of the visual features. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Logo** & **Channel** & **Shape** & **Tecture** & **Colored** & **Opacity** & **Position** & **Relative Size** \\  & & & & & & **(\% of the Screen)** \\ \hline  & RTP1a & Static & Static & Monochromatic & Opaque & Top Left Corner & 0.47\% \\  & RTP1b & Changes & Changes & Monochromatic & Opaque & Top Left Corner & 0.67\% and 0.47\% \\  & RTP2 & Static & Static & Monochromatic & Opaque & Top Left Corner & 0.45\% \\  & SIC & Static & Changes & Colored & Opaque & Top Left Corner & 0.42\% \\  & TVI & Static & Changes & Colored & Opaque & Top Left Corner & 0.50\% \\  & Eurosport & Static & Static & Monochromatic & Transparent & Top Right Corner & 0.48\% \\  & FOX HD & Static & Static & Monochromatic & Opaque & Top Right Corner & 0.48\% \\  & CMTV & Static & Changes & Colored & Opaque & Top Left Corner & 0.65\% \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Description of the general characteristics of the logos in the annotated dataset. Given the differences between streams and even within the same stream, we defined three increasingly difficulty levels, based on visual complexity, to classify the streams and enable an objective assessment.