# Vendored from https://raw.githubusercontent.com/CompVis/taming-transformers/24268930bf1dce879235a7fddd0b2355b84d7ea6/taming/modules/vqvae/quantize.py, # where the license is as follows: # # Copyright (c) 2020 Patrick Esser and Robin Rombach and Björn Ommer # # Permission is hereby granted, free of charge, to any person obtaining a copy # of this software and associated documentation files (the "Software"), to deal # in the Software without restriction, including without limitation the rights # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell # copies of the Software, and to permit persons to whom the Software is # furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be included in all # copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. # IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, # DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR # OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE # OR OTHER DEALINGS IN THE SOFTWARE./ import torch import torch.nn as nn import numpy as np from einops import rearrange class VectorQuantizer2(nn.Module): """ Improved version over VectorQuantizer, can be used as a drop-in replacement. Mostly avoids costly matrix multiplications and allows for post-hoc remapping of indices. """ # NOTE: due to a bug the beta term was applied to the wrong term. for # backwards compatibility we use the buggy version by default, but you can # specify legacy=False to fix it. def __init__(self, n_e, e_dim, beta, remap=None, unknown_index="random", sane_index_shape=False, legacy=True): super().__init__() self.n_e = n_e self.e_dim = e_dim self.beta = beta self.legacy = legacy self.embedding = nn.Embedding(self.n_e, self.e_dim) self.embedding.weight.data.uniform_(-1.0 / self.n_e, 1.0 / self.n_e) self.remap = remap if self.remap is not None: self.register_buffer("used", torch.tensor(np.load(self.remap))) self.re_embed = self.used.shape[0] self.unknown_index = unknown_index # "random" or "extra" or integer if self.unknown_index == "extra": self.unknown_index = self.re_embed self.re_embed = self.re_embed + 1 print(f"Remapping {self.n_e} indices to {self.re_embed} indices. " f"Using {self.unknown_index} for unknown indices.") else: self.re_embed = n_e self.sane_index_shape = sane_index_shape def remap_to_used(self, inds): ishape = inds.shape assert len(ishape) > 1 inds = inds.reshape(ishape[0], -1) used = self.used.to(inds) match = (inds[:, :, None] == used[None, None, ...]).long() new = match.argmax(-1) unknown = match.sum(2) < 1 if self.unknown_index == "random": new[unknown] = torch.randint(0, self.re_embed, size=new[unknown].shape).to(device=new.device) else: new[unknown] = self.unknown_index return new.reshape(ishape) def unmap_to_all(self, inds): ishape = inds.shape assert len(ishape) > 1 inds = inds.reshape(ishape[0], -1) used = self.used.to(inds) if self.re_embed > self.used.shape[0]: # extra token inds[inds >= self.used.shape[0]] = 0 # simply set to zero back = torch.gather(used[None, :][inds.shape[0] * [0], :], 1, inds) return back.reshape(ishape) def forward(self, z, temp=None, rescale_logits=False, return_logits=False): assert temp is None or temp == 1.0, "Only for interface compatible with Gumbel" assert rescale_logits is False, "Only for interface compatible with Gumbel" assert return_logits is False, "Only for interface compatible with Gumbel" # reshape z -> (batch, height, width, channel) and flatten z = rearrange(z, 'b c h w -> b h w c').contiguous() z_flattened = z.view(-1, self.e_dim) # distances from z to embeddings e_j (z - e)^2 = z^2 + e^2 - 2 e * z d = torch.sum(z_flattened ** 2, dim=1, keepdim=True) + \ torch.sum(self.embedding.weight ** 2, dim=1) - 2 * \ torch.einsum('bd,dn->bn', z_flattened, rearrange(self.embedding.weight, 'n d -> d n')) min_encoding_indices = torch.argmin(d, dim=1) z_q = self.embedding(min_encoding_indices).view(z.shape) perplexity = None min_encodings = None # compute loss for embedding if not self.legacy: loss = self.beta * torch.mean((z_q.detach() - z) ** 2) + \ torch.mean((z_q - z.detach()) ** 2) else: loss = torch.mean((z_q.detach() - z) ** 2) + self.beta * \ torch.mean((z_q - z.detach()) ** 2) # preserve gradients z_q = z + (z_q - z).detach() # reshape back to match original input shape z_q = rearrange(z_q, 'b h w c -> b c h w').contiguous() if self.remap is not None: min_encoding_indices = min_encoding_indices.reshape(z.shape[0], -1) # add batch axis min_encoding_indices = self.remap_to_used(min_encoding_indices) min_encoding_indices = min_encoding_indices.reshape(-1, 1) # flatten if self.sane_index_shape: min_encoding_indices = min_encoding_indices.reshape( z_q.shape[0], z_q.shape[2], z_q.shape[3]) return z_q, loss, (perplexity, min_encodings, min_encoding_indices) def get_codebook_entry(self, indices, shape): # shape specifying (batch, height, width, channel) if self.remap is not None: indices = indices.reshape(shape[0], -1) # add batch axis indices = self.unmap_to_all(indices) indices = indices.reshape(-1) # flatten again # get quantized latent vectors z_q = self.embedding(indices) if shape is not None: z_q = z_q.view(shape) # reshape back to match original input shape z_q = z_q.permute(0, 3, 1, 2).contiguous() return z_q