Class UNet2DModel

src/diffusers/models/unets/unet_2d.py:39–353

r""" A 2D UNet model that takes a noisy sample and a timestep and returns a sample shaped output. This model inherits from [`ModelMixin`]. Check the superclass documentation for it's generic methods implemented for all models (such as downloading or saving). Parameters: sam

class UNet2DModel(ModelMixin, ConfigMixin):
    r"""
    A 2D UNet model that takes a noisy sample and a timestep and returns a sample shaped output.

    This model inherits from [`ModelMixin`]. Check the superclass documentation for it's generic methods implemented
    for all models (such as downloading or saving).

    Parameters:
        sample_size (`int` or `tuple[int, int]`, *optional*, defaults to `None`):
            Height and width of input/output sample. Dimensions must be a multiple of `2 ** (len(block_out_channels) -
            1)`.
        in_channels (`int`, *optional*, defaults to 3): Number of channels in the input sample.
        out_channels (`int`, *optional*, defaults to 3): Number of channels in the output.
        center_input_sample (`bool`, *optional*, defaults to `False`): Whether to center the input sample.
        time_embedding_type (`str`, *optional*, defaults to `"positional"`): Type of time embedding to use.
        freq_shift (`int`, *optional*, defaults to 0): Frequency shift for Fourier time embedding.
        flip_sin_to_cos (`bool`, *optional*, defaults to `True`):
            Whether to flip sin to cos for Fourier time embedding.
        down_block_types (`tuple[str]`, *optional*, defaults to `("DownBlock2D", "AttnDownBlock2D", "AttnDownBlock2D", "AttnDownBlock2D")`):
            tuple of downsample block types.
        mid_block_type (`str`, *optional*, defaults to `"UNetMidBlock2D"`):
            Block type for middle of UNet, it can be either `UNetMidBlock2D` or `None`.
        up_block_types (`tuple[str]`, *optional*, defaults to `("AttnUpBlock2D", "AttnUpBlock2D", "AttnUpBlock2D", "UpBlock2D")`):
            tuple of upsample block types.
        block_out_channels (`tuple[int]`, *optional*, defaults to `(224, 448, 672, 896)`):
            tuple of block output channels.
        layers_per_block (`int`, *optional*, defaults to `2`): The number of layers per block.
        mid_block_scale_factor (`float`, *optional*, defaults to `1`): The scale factor for the mid block.
        downsample_padding (`int`, *optional*, defaults to `1`): The padding for the downsample convolution.
        downsample_type (`str`, *optional*, defaults to `conv`):
            The downsample type for downsampling layers. Choose between "conv" and "resnet"
        upsample_type (`str`, *optional*, defaults to `conv`):
            The upsample type for upsampling layers. Choose between "conv" and "resnet"
        dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use.
        act_fn (`str`, *optional*, defaults to `"silu"`): The activation function to use.
        attention_head_dim (`int`, *optional*, defaults to `8`): The attention head dimension.
        norm_num_groups (`int`, *optional*, defaults to `32`): The number of groups for normalization.
        attn_norm_num_groups (`int`, *optional*, defaults to `None`):
            If set to an integer, a group norm layer will be created in the mid block's [`Attention`] layer with the
            given number of groups. If left as `None`, the group norm layer will only be created if
            `resnet_time_scale_shift` is set to `default`, and if created will have `norm_num_groups` groups.
        norm_eps (`float`, *optional*, defaults to `1e-5`): The epsilon for normalization.
        resnet_time_scale_shift (`str`, *optional*, defaults to `"default"`): Time scale shift config
            for ResNet blocks (see [`~models.resnet.ResnetBlock2D`]). Choose from `default` or `scale_shift`.
        class_embed_type (`str`, *optional*, defaults to `None`):
            The type of class embedding to use which is ultimately summed with the time embeddings. Choose from `None`,
            `"timestep"`, or `"identity"`.
        num_class_embeds (`int`, *optional*, defaults to `None`):
            Input dimension of the learnable embedding matrix to be projected to `time_embed_dim` when performing class
            conditioning with `class_embed_type` equal to `None`.
    """

    _supports_gradient_checkpointing = True
    _skip_layerwise_casting_patterns = ["norm"]

    @register_to_config
    def __init__(
        self,