Table 4.

Data augmentation operations used during the investigations. We list both the augmentations names and descriptions.

Augmentation Name	Augmentation Description
Image noise	Adds salt-and-pepper noise to image. Namely, random pixels get randomly coloured towards white. Spreading power of modified pixels can be set by a parameter; hence, different augmentations can be considered as being more or less noisy.
Colour jittering	Adjusts the colour of RGB image I with a randomly selected value of hue, saturation, brightness, and contrast from the HSV colour space. Specify the range of each type of adjustment using name-value pair arguments. Four augmentations can be retrieved.
Flip	Images are flipped either from left to right or upside down.
Centre cropping	Images are centre cropped using a 150 × 150 window to ensure that Covid-19 patterns are selected during operation.