The fastai library includes several pretrained models from torchvision, namely:
- resnet18, resnet34, resnet50, resnet101, resnet152
- squeezenet1_0, squeezenet1_1
- densenet121, densenet169, densenet201, densenet161
- vgg16_bn, vgg19_bn
On top of the models offered by torchvision, fastai has implementations for the following models:
Create a Darknet with blocks of sizes given in
num_blocks, ending with
num_classes and using
nf initial features. Darknet53 uses
num_blocks = [1,2,8,8,4].
Wide ResNet with
num_groups and a width of
Each group contains
start_nf the initial number of features. Dropout of
drop_p is applied in between the two convolutions in each block. The expected input channel size is fixed at 3.
Structure: initial convolution ->
N blocks -> final layers of regularization and pooling
The first block of each group joins a path containing 2 convolutions with filter size 3x3 (and various regularizations) with another path containing a single convolution with a filter size of 1x1. All other blocks in each group follow the more traditional res_block style, i.e., the input of the path with two convs is added to the output of that path.
In the first group the stride is 1 for all convolutions. In all subsequent groups the stride in the first convolution of the first block is 2 and then all following convolutions have a stride of 1. Padding is always 1.