# Copyright 2023 The HuggingFace Team. All rights reserved. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. from dataclasses import dataclass from typing import Dict, Optional, Tuple, Union import torch import torch.nn as nn from ..configuration_utils import ConfigMixin, register_to_config from ..utils import BaseOutput, apply_forward_hook from .attention_processor import AttentionProcessor, AttnProcessor from .modeling_utils import ModelMixin from .vae import Decoder, DecoderOutput, DiagonalGaussianDistribution, Encoder @dataclass class AutoencoderKLOutput(BaseOutput): """ Output of AutoencoderKL encoding method. Args: latent_dist (`DiagonalGaussianDistribution`): Encoded outputs of `Encoder` represented as the mean and logvar of `DiagonalGaussianDistribution`. `DiagonalGaussianDistribution` allows for sampling latents from the distribution. """ latent_dist: "DiagonalGaussianDistribution" class AutoencoderKL(ModelMixin, ConfigMixin): r""" A VAE model with KL loss for encoding images into latents and decoding latent representations into images. This model inherits from [`ModelMixin`]. Check the superclass documentation for it's generic methods implemented for all models (such as downloading or saving). Parameters: in_channels (int, *optional*, defaults to 3): Number of channels in the input image. out_channels (int, *optional*, defaults to 3): Number of channels in the output. down_block_types (`Tuple[str]`, *optional*, defaults to `("DownEncoderBlock2D",)`): Tuple of downsample block types. up_block_types (`Tuple[str]`, *optional*, defaults to `("UpDecoderBlock2D",)`): Tuple of upsample block types. block_out_channels (`Tuple[int]`, *optional*, defaults to `(64,)`): Tuple of block output channels. act_fn (`str`, *optional*, defaults to `"silu"`): The activation function to use. latent_channels (`int`, *optional*, defaults to 4): Number of channels in the latent space. sample_size (`int`, *optional*, defaults to `32`): Sample input size. scaling_factor (`float`, *optional*, defaults to 0.18215): The component-wise standard deviation of the trained latent space computed using the first batch of the training set. This is used to scale the latent space to have unit variance when training the diffusion model. The latents are scaled with the formula `z = z * scaling_factor` before being passed to the diffusion model. When decoding, the latents are scaled back to the original scale with the formula: `z = 1 / scaling_factor * z`. For more details, refer to sections 4.3.2 and D.1 of the [High-Resolution Image Synthesis with Latent Diffusion Models](https://arxiv.org/abs/2112.10752) paper. """ _supports_gradient_checkpointing = True @register_to_config def __init__( self, in_channels: int = 3, out_channels: int = 3, down_block_types: Tuple[str] = ("DownEncoderBlock2D",), up_block_types: Tuple[str] = ("UpDecoderBlock2D",), block_out_channels: Tuple[int] = (64,), layers_per_block: int = 1, act_fn: str = "silu", latent_channels: int = 4, norm_num_groups: int = 32, sample_size: int = 32, scaling_factor: float = 0.18215, ): super().__init__() # pass init params to Encoder self.encoder = Encoder( in_channels=in_channels, out_channels=latent_channels, down_block_types=down_block_types, block_out_channels=block_out_channels, layers_per_block=layers_per_block, act_fn=act_fn, norm_num_groups=norm_num_groups, double_z=True, ) # pass init params to Decoder self.decoder = Decoder( in_channels=latent_channels, out_channels=out_channels, up_block_types=up_block_types, block_out_channels=block_out_channels, layers_per_block=layers_per_block, norm_num_groups=norm_num_groups, act_fn=act_fn, ) self.quant_conv = nn.Conv2d(2 * latent_channels, 2 * latent_channels, 1) self.post_quant_conv = nn.Conv2d(latent_channels, latent_channels, 1) self.use_slicing = False self.use_tiling = False # only relevant if vae tiling is enabled self.tile_sample_min_size = self.config.sample_size sample_size = ( self.config.sample_size[0] if isinstance(self.config.sample_size, (list, tuple)) else self.config.sample_size ) self.tile_latent_min_size = int(sample_size / (2 ** (len(self.config.block_out_channels) - 1))) self.tile_overlap_factor = 0.25 def _set_gradient_checkpointing(self, module, value=False): if isinstance(module, (Encoder, Decoder)): module.gradient_checkpointing = value def enable_tiling(self, use_tiling: bool = True): r""" Enable tiled VAE decoding. When this option is enabled, the VAE will split the input tensor into tiles to compute decoding and encoding in several steps. This is useful for saving a large amount of memory and to allow processing larger images. """ self.use_tiling = use_tiling def disable_tiling(self): r""" Disable tiled VAE decoding. If `enable_tiling` was previously enabled, this method will go back to computing decoding in one step. """ self.enable_tiling(False) def enable_slicing(self): r""" Enable sliced VAE decoding. When this option is enabled, the VAE will split the input tensor in slices to compute decoding in several steps. This is useful to save some memory and allow larger batch sizes. """ self.use_slicing = True def disable_slicing(self): r""" Disable sliced VAE decoding. If `enable_slicing` was previously enabled, this method will go back to computing decoding in one step. """ self.use_slicing = False @property # Copied from diffusers.models.unet_2d_condition.UNet2DConditionModel.attn_processors def attn_processors(self) -> Dict[str, AttentionProcessor]: r""" Returns: `dict` of attention processors: A dictionary containing all attention processors used in the model with indexed by its weight name. """ # set recursively processors = {} def fn_recursive_add_processors(name: str, module: torch.nn.Module, processors: Dict[str, AttentionProcessor]): if hasattr(module, "set_processor"): processors[f"{name}.processor"] = module.processor for sub_name, child in module.named_children(): fn_recursive_add_processors(f"{name}.{sub_name}", child, processors) return processors for name, module in self.named_children(): fn_recursive_add_processors(name, module, processors) return processors # Copied from diffusers.models.unet_2d_condition.UNet2DConditionModel.set_attn_processor def set_attn_processor(self, processor: Union[AttentionProcessor, Dict[str, AttentionProcessor]]): r""" Sets the attention processor to use to compute attention. Parameters: processor (`dict` of `AttentionProcessor` or only `AttentionProcessor`): The instantiated processor class or a dictionary of processor classes that will be set as the processor for **all** `Attention` layers. If `processor` is a dict, the key needs to define the path to the corresponding cross attention processor. This is strongly recommended when setting trainable attention processors. """ count = len(self.attn_processors.keys()) if isinstance(processor, dict) and len(processor) != count: raise ValueError( f"A dict of processors was passed, but the number of processors {len(processor)} does not match the" f" number of attention layers: {count}. Please make sure to pass {count} processor classes." ) def fn_recursive_attn_processor(name: str, module: torch.nn.Module, processor): if hasattr(module, "set_processor"): if not isinstance(processor, dict): module.set_processor(processor) else: module.set_processor(processor.pop(f"{name}.processor")) for sub_name, child in module.named_children(): fn_recursive_attn_processor(f"{name}.{sub_name}", child, processor) for name, module in self.named_children(): fn_recursive_attn_processor(name, module, processor) # Copied from diffusers.models.unet_2d_condition.UNet2DConditionModel.set_default_attn_processor def set_default_attn_processor(self): """ Disables custom attention processors and sets the default attention implementation. """ self.set_attn_processor(AttnProcessor()) @apply_forward_hook def encode(self, x: torch.FloatTensor, return_dict: bool = True) -> AutoencoderKLOutput: if self.use_tiling and (x.shape[-1] > self.tile_sample_min_size or x.shape[-2] > self.tile_sample_min_size): return self.tiled_encode(x, return_dict=return_dict) if self.use_slicing and x.shape[0] > 1: encoded_slices = [self.encoder(x_slice) for x_slice in x.split(1)] h = torch.cat(encoded_slices) else: h = self.encoder(x) moments = self.quant_conv(h) posterior = DiagonalGaussianDistribution(moments) if not return_dict: return (posterior,) return AutoencoderKLOutput(latent_dist=posterior) def _decode(self, z: torch.FloatTensor, return_dict: bool = True) -> Union[DecoderOutput, torch.FloatTensor]: if self.use_tiling and (z.shape[-1] > self.tile_latent_min_size or z.shape[-2] > self.tile_latent_min_size): return self.tiled_decode(z, return_dict=return_dict) z = self.post_quant_conv(z) dec = self.decoder(z) if not return_dict: return (dec,) return DecoderOutput(sample=dec) @apply_forward_hook def decode(self, z: torch.FloatTensor, return_dict: bool = True) -> Union[DecoderOutput, torch.FloatTensor]: if self.use_slicing and z.shape[0] > 1: decoded_slices = [self._decode(z_slice).sample for z_slice in z.split(1)] decoded = torch.cat(decoded_slices) else: decoded = self._decode(z).sample if not return_dict: return (decoded,) return DecoderOutput(sample=decoded) def blend_v(self, a, b, blend_extent): blend_extent = min(a.shape[2], b.shape[2], blend_extent) for y in range(blend_extent): b[:, :, y, :] = a[:, :, -blend_extent + y, :] * (1 - y / blend_extent) + b[:, :, y, :] * (y / blend_extent) return b def blend_h(self, a, b, blend_extent): blend_extent = min(a.shape[3], b.shape[3], blend_extent) for x in range(blend_extent): b[:, :, :, x] = a[:, :, :, -blend_extent + x] * (1 - x / blend_extent) + b[:, :, :, x] * (x / blend_extent) return b def tiled_encode(self, x: torch.FloatTensor, return_dict: bool = True) -> AutoencoderKLOutput: r"""Encode a batch of images using a tiled encoder. When this option is enabled, the VAE will split the input tensor into tiles to compute encoding in several steps. This is useful to keep memory use constant regardless of image size. The end result of tiled encoding is different from non-tiled encoding because each tile uses a different encoder. To avoid tiling artifacts, the tiles overlap and are blended together to form a smooth output. You may still see tile-sized changes in the output, but they should be much less noticeable. Args: x (`torch.FloatTensor`): Input batch of images. return_dict (`bool`, *optional*, defaults to `True`): Whether or not to return a [`~models.autoencoder_kl.AutoencoderKLOutput`] instead of a plain tuple. Returns: [`~models.autoencoder_kl.AutoencoderKLOutput`] or `tuple`: If return_dict is True, a [`~models.autoencoder_kl.AutoencoderKLOutput`] is returned, otherwise a plain `tuple` is returned. """ overlap_size = int(self.tile_sample_min_size * (1 - self.tile_overlap_factor)) blend_extent = int(self.tile_latent_min_size * self.tile_overlap_factor) row_limit = self.tile_latent_min_size - blend_extent # Split the image into 512x512 tiles and encode them separately. rows = [] for i in range(0, x.shape[2], overlap_size): row = [] for j in range(0, x.shape[3], overlap_size): tile = x[:, :, i : i + self.tile_sample_min_size, j : j + self.tile_sample_min_size] tile = self.encoder(tile) tile = self.quant_conv(tile) row.append(tile) rows.append(row) result_rows = [] for i, row in enumerate(rows): result_row = [] for j, tile in enumerate(row): # blend the above tile and the left tile # to the current tile and add the current tile to the result row if i > 0: tile = self.blend_v(rows[i - 1][j], tile, blend_extent) if j > 0: tile = self.blend_h(row[j - 1], tile, blend_extent) result_row.append(tile[:, :, :row_limit, :row_limit]) result_rows.append(torch.cat(result_row, dim=3)) moments = torch.cat(result_rows, dim=2) posterior = DiagonalGaussianDistribution(moments) if not return_dict: return (posterior,) return AutoencoderKLOutput(latent_dist=posterior) def tiled_decode(self, z: torch.FloatTensor, return_dict: bool = True) -> Union[DecoderOutput, torch.FloatTensor]: r""" Decode a batch of images using a tiled decoder. Args: z (`torch.FloatTensor`): Input batch of latent vectors. return_dict (`bool`, *optional*, defaults to `True`): Whether or not to return a [`~models.vae.DecoderOutput`] instead of a plain tuple. Returns: [`~models.vae.DecoderOutput`] or `tuple`: If return_dict is True, a [`~models.vae.DecoderOutput`] is returned, otherwise a plain `tuple` is returned. """ overlap_size = int(self.tile_latent_min_size * (1 - self.tile_overlap_factor)) blend_extent = int(self.tile_sample_min_size * self.tile_overlap_factor) row_limit = self.tile_sample_min_size - blend_extent # Split z into overlapping 64x64 tiles and decode them separately. # The tiles have an overlap to avoid seams between tiles. rows = [] for i in range(0, z.shape[2], overlap_size): row = [] for j in range(0, z.shape[3], overlap_size): tile = z[:, :, i : i + self.tile_latent_min_size, j : j + self.tile_latent_min_size] tile = self.post_quant_conv(tile) decoded = self.decoder(tile) row.append(decoded) rows.append(row) result_rows = [] for i, row in enumerate(rows): result_row = [] for j, tile in enumerate(row): # blend the above tile and the left tile # to the current tile and add the current tile to the result row if i > 0: tile = self.blend_v(rows[i - 1][j], tile, blend_extent) if j > 0: tile = self.blend_h(row[j - 1], tile, blend_extent) result_row.append(tile[:, :, :row_limit, :row_limit]) result_rows.append(torch.cat(result_row, dim=3)) dec = torch.cat(result_rows, dim=2) if not return_dict: return (dec,) return DecoderOutput(sample=dec) def forward( self, sample: torch.FloatTensor, sample_posterior: bool = False, return_dict: bool = True, generator: Optional[torch.Generator] = None, ) -> Union[DecoderOutput, torch.FloatTensor]: r""" Args: sample (`torch.FloatTensor`): Input sample. sample_posterior (`bool`, *optional*, defaults to `False`): Whether to sample from the posterior. return_dict (`bool`, *optional*, defaults to `True`): Whether or not to return a [`DecoderOutput`] instead of a plain tuple. """ x = sample posterior = self.encode(x).latent_dist if sample_posterior: z = posterior.sample(generator=generator) else: z = posterior.mode() dec = self.decode(z).sample if not return_dict: return (dec,) return DecoderOutput(sample=dec)