criteria/model_irse.py

from torch.nn import (
    Linear,
    Conv2d,
    BatchNorm1d,
    BatchNorm2d,
    PReLU,
    Dropout,
    Sequential,
    Module,
)
from criteria.helpers import (
    get_blocks,
    Flatten,
    bottleneck_IR,
    bottleneck_IR_SE,
    l2_norm,
)

"""
Modified Backbone implementation from [TreB1eN](https://github.com/TreB1eN/InsightFace_Pytorch)
"""


class Backbone(Module):
    def __init__(self, input_size, num_layers, mode="ir", drop_ratio=0.4, affine=True):
        super(Backbone, self).__init__()
        assert input_size in [112, 224], "input_size should be 112 or 224"
        assert num_layers in [50, 100, 152], "num_layers should be 50, 100 or 152"
        assert mode in ["ir", "ir_se"], "mode should be ir or ir_se"
        blocks = get_blocks(num_layers)
        if mode == "ir":
            unit_module = bottleneck_IR
        elif mode == "ir_se":
            unit_module = bottleneck_IR_SE
        self.input_layer = Sequential(
            Conv2d(3, 64, (3, 3), 1, 1, bias=False), BatchNorm2d(64), PReLU(64)
        )
        if input_size == 112:
            self.output_layer = Sequential(
                BatchNorm2d(512),
                Dropout(drop_ratio),
                Flatten(),
                Linear(512 * 7 * 7, 512),
                BatchNorm1d(512, affine=affine),
            )
        else:
            self.output_layer = Sequential(
                BatchNorm2d(512),
                Dropout(drop_ratio),
                Flatten(),
                Linear(512 * 14 * 14, 512),
                BatchNorm1d(512, affine=affine),
            )

        modules = []
        for block in blocks:
            for bottleneck in block:
                modules.append(
                    unit_module(
                        bottleneck.in_channel, bottleneck.depth, bottleneck.stride
                    )
                )
        self.body = Sequential(*modules)

    def forward(self, x):
        x = self.input_layer(x)
        x = self.body(x)
        x = self.output_layer(x)
        return l2_norm(x)


def IR_50(input_size):
    """Constructs a ir-50 model."""
    model = Backbone(input_size, num_layers=50, mode="ir", drop_ratio=0.4, affine=False)
    return model


def IR_101(input_size):
    """Constructs a ir-101 model."""
    model = Backbone(
        input_size, num_layers=100, mode="ir", drop_ratio=0.4, affine=False
    )
    return model


def IR_152(input_size):
    """Constructs a ir-152 model."""
    model = Backbone(
        input_size, num_layers=152, mode="ir", drop_ratio=0.4, affine=False
    )
    return model


def IR_SE_50(input_size):
    """Constructs a ir_se-50 model."""
    model = Backbone(
        input_size, num_layers=50, mode="ir_se", drop_ratio=0.4, affine=False
    )
    return model


def IR_SE_101(input_size):
    """Constructs a ir_se-101 model."""
    model = Backbone(
        input_size, num_layers=100, mode="ir_se", drop_ratio=0.4, affine=False
    )
    return model


def IR_SE_152(input_size):
    """Constructs a ir_se-152 model."""
    model = Backbone(
        input_size, num_layers=152, mode="ir_se", drop_ratio=0.4, affine=False
    )
    return model