Table 2.

The representation of COVID‐19 imaging data from different ML method

COVID‐19 imaging data representation	Modalities	ML model	Study
3D feature maps	CT	Attention‐based deep 3D multiple instance learning	44
Latent high‐level representation	CT	CPM‐Nets 45 multiview representation learning technique	46
		Adaptive feature selection guided deep forest (AFS‐DF)	47
Image pyramid representation	CT	The multiscale spatial pyramid (MSSP) decomposition 48	49
Bag representation	CT	Attention based deep 3D multi‐instance learning (AD3D‐MIL)	44
One‐hot representation	CT	Adapted 3D ResNet‐18	17
64‐dimensional DL features	CT	DenseNet‐like structure 50	51
Activation maps	X‐ray	MobileNetV2, 40 SqueezeNet, 52 Deep CNN architecture	21, 53, 54, 55

Abbreviations: CNN, convolutional neural network; CT, computed tomography.