## 2 Materials and Methods
### Clinical Benchmark  
To benchmark the performance of the proposed algorithm, a prospective, endoscopist-blinded, noninterventional study was conducted at the Maastricht University Medical Center+ (MUMC+) and Catharina Hospital Eindhoven (CZE). The study was in accordance with the declaration of Helsinki as well as the General Data Protection Regulation. A total of 19 endoscopists optically diagnosed 60 colonoscopy images containing a single polyp acquired in WL, BLI, and LCI modalities (later referred to as test data). Two person groups were derived from the medical professionals. The first group consisted of six expert endoscopists from the international BLI-expert group, who were knowledgeable in using BLI and BLI Adenoma Serrated International Classification (BASIC) [13; 38] (Table 2) and brought an experience of more than 2000 colonoscopies. The second group consisted of thirteen Dutch novices with limited colonoscopy experience (<400 colonoscopies) and without prior experience in using BLI or BASIC.  
The benchmark study was divided in two stages. For both stages, only WL and BLI were present as modalities. In the first stage, the experts and novices were instructed to classify the set of 60 polyps between HP, SSA, or AD based on their intuition and expertise, with a time limit of 30 seconds. After a washout period of four weeks, the medical group was further trained in using BLI and BASIC. Following the instruction period, the same endoscopists were asked to classify the exact same dataset of polyps based on the BASIC classification [13]. Moreover, each endoscopist had to report the level of confidence for each CRP.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Accuracy (\%)** & **Specificity (\%)** & **Sensitivity (\%)** & **AUC** \\ \hline \hline \begin{tabular}{c} Intuition (\(\pm\)SD) \\ \end{tabular} & \begin{tabular}{c} 66.7 \(\pm\) 8.4 \\ 79.5 \(\pm\) 6.6 \\ 70.7 \(\pm\) 9.8 \\ \end{tabular} & \begin{tabular}{c} 93.2 \(\pm\) 4.0 \\ 95.6 \(\pm\) 4.9 \\ 93.9 \(\pm\) 4.3 \\ \end{tabular} & \begin{tabular}{c} 46.2 \(\pm\) 16.7 \\ 50.0 \(\pm\) 16.2 \\ 47.4 \(\pm\) 16.2 \\ \end{tabular} & \begin{tabular}{c} N.A \\ N.A \\ N.A \\ \end{tabular} \\ \hline \begin{tabular}{c} BASIC (\(\pm\)SD) \\ \end{tabular} & \begin{tabular}{c} 66.5 \(\pm\) 9.3 \\ 81.7 \(\pm\) 4.2 \\ 71.3 \(\pm\) 10.7 \\ \end{tabular} & \begin{tabular}{c} 92.1 \(\pm\) 6.2 \\ 94.1 \(\pm\) 1.8 \\ 92.7 \(\pm\) 5.2 \\ \end{tabular} & \begin{tabular}{c} 55.4 \(\pm\) 14.7 \\ 61.1 \(\pm\) 5.0 \\ 57.2 \(\pm\) 12.6 \\ \end{tabular} & \begin{tabular}{c} N.A \\ N.A \\ N.A \\ \end{tabular} \\ \hline \begin{tabular}{c} CADx \\ \end{tabular} & \begin{tabular}{c} VGG16 \\ ResNet50V2 \\ ResNet101V2 \\ \end{tabular} & 85.0 & 84.4 & 86.7 & 0.90 \\ \
\begin{tabular}{c} ResNet50V2 \\ ResNet101V2 \\ \end{tabular} & 83.3 & 93.3 & 80.0 & 0.92 \\
\begin{tabular}{c} Xception \\ InceptionResNetV2 \\ EfficientNetB4 \\ \end{tabular} & 85.0 & 93.3 & 73.3 & 0.94 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of our computer aided diagnosis (CADx) results with the group of endoscopists. The first block presents the results of the experts and novices based on their intuition. The second block shows the results of the endoscopists after the post-training stage on the BLI Adenoma Serrated International Classification (BASIC) classification. The third block includes the CADx results of WL, BLI, and LCI combined modalities, evaluated with common state-of-the art architectures in polyp classification.