class CNN(nn.Module):
def __init__(self, num_chars):
super(CNN, self).__init__()
# Convolution Layer
self.conv1 = nn.Conv2d(3, 128, kernel_size=(3, 6), padding=(1, 1))
self.pool1 = nn.MaxPool2d(kernel_size=(2, 2))
self.conv2 = nn.Conv2d(128, 64, kernel_size=(3, 6), padding=(1, 1))
self.pool2 = nn.MaxPool2d(kernel_size=(2, 2))
# Dense Layer
self.fc1 = nn.Linear(768, 64)
self.dp1 = nn.Dropout(0.2)
# Recurrent Layer
self.lstm = nn.GRU(64, 32, bidirectional=True)
# Output Layer
self.output = nn.Linear(64, num_chars + 1)
def forward(self, images, targets=None):
bs, _, _, _ = images.size()
x = F.relu(self.conv1(images))
x = self.pool1(x)
x = F.relu(self.conv2(x))
x = self.pool2(x)
x = x.permute(0, 3, 1, 2)
x = x.view(bs, x.size(1), -1)
x = F.relu(self.fc1(x))
x = self.dp1(x)
x, _ = self.lstm(x)
x = self.output(x)
x = x.permute(1, 0, 2)
if targets is not None:
log_probs = F.log_softmax(x, 2)
input_lengths = torch.full(
size=(bs,), fill_value=log_probs.size(0), dtype=torch.int32
)
target_lengths = torch.full(
size=(bs,), fill_value=targets.size(1), dtype=torch.int32
)
loss = nn.CTCLoss(blank=0)(
log_probs, targets, input_lengths, target_lengths
)
return x, loss
return x, None
if __name__ == '__main__':
model = CNN(74)
img = torch.rand(config.BATCH_SIZE, 3, 50, 200)
target = torch.randint(1, 20, (config.BATCH_SIZE, 5))
x, loss = model(img, target)
print(loss)