Fig. 1.

Schematic representation of five-fold cross-validation. Each row represents one of the five ‘folds’ used in the validation process, with a total of 30 patient videos divided into training and validation sets. The columns represent individual patient videos, each containing 10 images, as indicated by the numbers 1 through 30. Shaded boxes within each fold indicate the videos selected as the validation set for that particular cycle, with the remaining videos used as the training set. Each video serves as part of the validation set once throughout the five cycles, ensuring that every video contributes to the validation of the model, while being used four times in the training set.