blur sigma for upsampling training was 0.6 in the paper, make that the default value

README.md

@@ -368,7 +368,8 @@ unet1 = Unet(
     image_embed_dim = 512,
     cond_dim = 128,
     channels = 3,
-    dim_mults=(1, 2, 4, 8)
+    dim_mults=(1, 2, 4, 8),
+    cond_on_text_encodings = True    # set to True for any unets that need to be conditioned on text encodings
 ).cuda()
 
 unet2 = Unet(
@@ -385,8 +386,7 @@ decoder = Decoder(
     clip = clip,
     timesteps = 100,
     image_cond_drop_prob = 0.1,
-    text_cond_drop_prob = 0.5,
-    condition_on_text_encodings = False  # set this to True if you wish to condition on text during training and sampling
+    text_cond_drop_prob = 0.5
 ).cuda()
 
 for unet_number in (1, 2):
@@ -1189,4 +1189,14 @@ Once built, images will be saved to the same directory the command is invoked
 }
 ```
 
+```bibtex
+@article{Saharia2021PaletteID,
+    title   = {Palette: Image-to-Image Diffusion Models},
+    author  = {Chitwan Saharia and William Chan and Huiwen Chang and Chris A. Lee and Jonathan Ho and Tim Salimans and David J. Fleet and Mohammad Norouzi},
+    journal = {ArXiv},
+    year    = {2021},
+    volume  = {abs/2111.05826}
+}
+```
+
 *Creating noise from data is easy; creating data from noise is generative modeling.* - <a href="https://arxiv.org/abs/2011.13456">Yang Song's paper</a>

dalle2_pytorch/dalle2_pytorch.py

@@ -45,6 +45,11 @@ def exists(val):
 def identity(t, *args, **kwargs):
     return t
 
+def first(arr, d = None):
+    if len(arr) == 0:
+        return d
+    return arr[0]
+
 def maybe(fn):
     @wraps(fn)
     def inner(x):
@@ -351,7 +356,7 @@ def cosine_beta_schedule(timesteps, s = 0.008):
     steps = timesteps + 1
     x = torch.linspace(0, timesteps, steps, dtype = torch.float64)
     alphas_cumprod = torch.cos(((x / timesteps) + s) / (1 + s) * torch.pi * 0.5) ** 2
-    alphas_cumprod = alphas_cumprod / alphas_cumprod[0]
+    alphas_cumprod = alphas_cumprod / first(alphas_cumprod)
     betas = 1 - (alphas_cumprod[1:] / alphas_cumprod[:-1])
     return torch.clip(betas, 0, 0.999)
 
@@ -1088,8 +1093,12 @@ class DiffusionPrior(nn.Module):
 
 # decoder
 
-def Upsample(dim):
-    return nn.ConvTranspose2d(dim, dim, 4, 2, 1)
+def Upsample(dim, dim_out = None):
+    dim_out = default(dim_out, dim)
+    return nn.Sequential(
+        nn.Upsample(scale_factor = 2, mode = 'nearest'),
+        nn.Conv2d(dim, dim_out, 3, padding = 1)
+    )
 
 def Downsample(dim, *, dim_out = None):
     dim_out = default(dim_out, dim)
@@ -1166,7 +1175,7 @@ class ResnetBlock(nn.Module):
         self.block2 = Block(dim_out, dim_out, groups = groups)
         self.res_conv = nn.Conv2d(dim, dim_out, 1) if dim != dim_out else nn.Identity()
 
-    def forward(self, x, cond = None, time_emb = None):
+    def forward(self, x, time_emb = None, cond = None):
 
         scale_shift = None
         if exists(self.time_mlp) and exists(time_emb):
@@ -1359,6 +1368,7 @@ class Unet(nn.Module):
         cross_embed_downsample = False,
         cross_embed_downsample_kernel_sizes = (2, 4),
         memory_efficient = False,
+        scale_skip_connection = False,
         **kwargs
     ):
         super().__init__()
@@ -1440,6 +1450,10 @@ class Unet(nn.Module):
         self.max_text_len = max_text_len
         self.null_text_embed = nn.Parameter(torch.randn(1, max_text_len, cond_dim))
 
+        # whether to scale skip connection, adopted in Imagen
+
+        self.skip_connect_scale = 1. if not scale_skip_connection else (2 ** -0.5)
+
         # attention related params
 
         attn_kwargs = dict(heads = attn_heads, dim_head = attn_dim_head)
@@ -1447,6 +1461,8 @@ class Unet(nn.Module):
         # resnet block klass
 
         resnet_groups = cast_tuple(resnet_groups, len(in_out))
+        top_level_resnet_group = first(resnet_groups)
+
         num_resnet_blocks = cast_tuple(num_resnet_blocks, len(in_out))
 
         assert len(resnet_groups) == len(in_out)
@@ -1457,23 +1473,32 @@ class Unet(nn.Module):
         if cross_embed_downsample:
             downsample_klass = partial(CrossEmbedLayer, kernel_sizes = cross_embed_downsample_kernel_sizes)
 
+        # give memory efficient unet an initial resnet block
+
+        self.init_resnet_block = ResnetBlock(init_dim, init_dim, time_cond_dim = time_cond_dim, groups = top_level_resnet_group) if memory_efficient else None
+
         # layers
 
         self.downs = nn.ModuleList([])
         self.ups = nn.ModuleList([])
         num_resolutions = len(in_out)
 
+        skip_connect_dims = []          # keeping track of skip connection dimensions
+
         for ind, ((dim_in, dim_out), groups, layer_num_resnet_blocks) in enumerate(zip(in_out, resnet_groups, num_resnet_blocks)):
             is_first = ind == 0
             is_last = ind >= (num_resolutions - 1)
             layer_cond_dim = cond_dim if not is_first else None
 
+            dim_layer = dim_out if memory_efficient else dim_in
+            skip_connect_dims.append(dim_layer)
+
             self.downs.append(nn.ModuleList([
                 downsample_klass(dim_in, dim_out = dim_out) if memory_efficient else None,
-                ResnetBlock(dim_out if memory_efficient else dim_in, dim_out, time_cond_dim = time_cond_dim, groups = groups),
-                Residual(LinearAttention(dim_out, **attn_kwargs)) if sparse_attn else nn.Identity(),
-                nn.ModuleList([ResnetBlock(dim_out, dim_out, cond_dim = layer_cond_dim, time_cond_dim = time_cond_dim, groups = groups) for _ in range(layer_num_resnet_blocks)]),
-                downsample_klass(dim_out) if not is_last and not memory_efficient else None
+                ResnetBlock(dim_layer, dim_layer, time_cond_dim = time_cond_dim, groups = groups),
+                Residual(LinearAttention(dim_layer, **attn_kwargs)) if sparse_attn else nn.Identity(),
+                nn.ModuleList([ResnetBlock(dim_layer, dim_layer, cond_dim = layer_cond_dim, time_cond_dim = time_cond_dim, groups = groups) for _ in range(layer_num_resnet_blocks)]),
+                downsample_klass(dim_layer, dim_out = dim_out) if not is_last and not memory_efficient else nn.Conv2d(dim_layer, dim_out, 1)
             ]))
 
         mid_dim = dims[-1]
@@ -1486,17 +1511,17 @@ class Unet(nn.Module):
             is_last = ind >= (len(in_out) - 1)
             layer_cond_dim = cond_dim if not is_last else None
 
+            skip_connect_dim = skip_connect_dims.pop()
+
             self.ups.append(nn.ModuleList([
-                ResnetBlock(dim_out * 2, dim_in, cond_dim = layer_cond_dim, time_cond_dim = time_cond_dim, groups = groups),
-                Residual(LinearAttention(dim_in, **attn_kwargs)) if sparse_attn else nn.Identity(),
-                nn.ModuleList([ResnetBlock(dim_in, dim_in, cond_dim = layer_cond_dim, time_cond_dim = time_cond_dim, groups = groups)  for _ in range(layer_num_resnet_blocks)]),
-                Upsample(dim_in) if not is_last or memory_efficient else nn.Identity()
+                ResnetBlock(dim_out + skip_connect_dim, dim_out, cond_dim = layer_cond_dim, time_cond_dim = time_cond_dim, groups = groups),
+                Residual(LinearAttention(dim_out, **attn_kwargs)) if sparse_attn else nn.Identity(),
+                nn.ModuleList([ResnetBlock(dim_out + skip_connect_dim, dim_out, cond_dim = layer_cond_dim, time_cond_dim = time_cond_dim, groups = groups)  for _ in range(layer_num_resnet_blocks)]),
+                Upsample(dim_out, dim_in) if not is_last or memory_efficient else nn.Identity()
             ]))
 
-        self.final_conv = nn.Sequential(
-            ResnetBlock(dim * 2, dim, groups = resnet_groups[0]),
-            nn.Conv2d(dim, self.channels_out, 1)
-        )
+        self.final_resnet_block = ResnetBlock(dim * 2, dim, time_cond_dim = time_cond_dim, groups = top_level_resnet_group)
+        self.to_out = nn.Conv2d(dim, self.channels_out, 3, padding = 1)
 
     # if the current settings for the unet are not correct
     # for cascading DDPM, then reinit the unet with the right settings
@@ -1660,6 +1685,11 @@ class Unet(nn.Module):
         c = self.norm_cond(c)
         mid_c = self.norm_mid_cond(mid_c)
 
+        # initial resnet block
+
+        if exists(self.init_resnet_block):
+            x = self.init_resnet_block(x, t)
+
         # go through the layers of the unet, down and up
 
         hiddens = []
@@ -1668,36 +1698,41 @@ class Unet(nn.Module):
             if exists(pre_downsample):
                 x = pre_downsample(x)
 
-            x = init_block(x, c, t)
+            x = init_block(x, t, c)
             x = sparse_attn(x)
+            hiddens.append(x)
 
             for resnet_block in resnet_blocks:
-                x = resnet_block(x, c, t)
-
-            hiddens.append(x)
+                x = resnet_block(x, t, c)
+                hiddens.append(x)
 
             if exists(post_downsample):
                 x = post_downsample(x)
 
-        x = self.mid_block1(x, mid_c, t)
+        x = self.mid_block1(x, t, mid_c)
 
         if exists(self.mid_attn):
             x = self.mid_attn(x)
 
-        x = self.mid_block2(x, mid_c, t)
+        x = self.mid_block2(x, t, mid_c)
+
+        connect_skip = lambda x: torch.cat((x, hiddens.pop() * self.skip_connect_scale), dim = 1)
 
         for init_block, sparse_attn, resnet_blocks, upsample in self.ups:
-            x = torch.cat((x, hiddens.pop()), dim = 1)
-            x = init_block(x, c, t)
+            x = connect_skip(x)
+            x = init_block(x, t, c)
             x = sparse_attn(x)
 
             for resnet_block in resnet_blocks:
-                x = resnet_block(x, c, t)
+                x = connect_skip(x)
+                x = resnet_block(x, t, c)
 
             x = upsample(x)
 
         x = torch.cat((x, r), dim = 1)
-        return self.final_conv(x)
+
+        x = self.final_resnet_block(x, t)
+        return self.to_out(x)
 
 class LowresConditioner(nn.Module):
     def __init__(
@@ -1764,7 +1799,7 @@ class Decoder(nn.Module):
         image_sizes = None,                         # for cascading ddpm, image size at each stage
         random_crop_sizes = None,                   # whether to random crop the image at that stage in the cascade (super resoluting convolutions at the end may be able to generalize on smaller crops)
         lowres_downsample_first = True,             # cascading ddpm - resizes to lower resolution, then to next conditional resolution + blur
-        blur_sigma = (0.1, 0.2),                    # cascading ddpm - blur sigma
+        blur_sigma = 0.6,                           # cascading ddpm - blur sigma
         blur_kernel_size = 3,                       # cascading ddpm - blur kernel size
         clip_denoised = True,
         clip_x_start = True,
@@ -1781,13 +1816,6 @@ class Decoder(nn.Module):
     ):
         super().__init__()
 
-        self.unconditional = unconditional
-
-        # text conditioning
-
-        assert not (condition_on_text_encodings and unconditional), 'unconditional decoder image generation cannot be set to True if conditioning on text is present'
-        self.condition_on_text_encodings = condition_on_text_encodings
-
         # clip
 
         self.clip = None
@@ -1819,12 +1847,16 @@ class Decoder(nn.Module):
 
         self.channels = channels
 
-        # automatically take care of ensuring that first unet is unconditional
-        # while the rest of the unets are conditioned on the low resolution image produced by previous unet
+        # verify conditioning method
 
         unets = cast_tuple(unet)
         num_unets = len(unets)
 
+        self.unconditional = unconditional
+
+        # automatically take care of ensuring that first unet is unconditional
+        # while the rest of the unets are conditioned on the low resolution image produced by previous unet
+
         vaes = pad_tuple_to_length(cast_tuple(vae), len(unets), fillvalue = NullVQGanVAE(channels = self.channels))
 
         # whether to use learned variance, defaults to True for the first unet in the cascade, as in paper
@@ -1852,7 +1884,7 @@ class Decoder(nn.Module):
             one_unet = one_unet.cast_model_parameters(
                 lowres_cond = not is_first,
                 cond_on_image_embeds = not unconditional and is_first,
-                cond_on_text_encodings = not unconditional and (is_first or one_unet.cond_on_text_encodings),
+                cond_on_text_encodings = not unconditional and one_unet.cond_on_text_encodings,
                 channels = unet_channels,
                 channels_out = unet_channels_out
             )
@@ -1860,6 +1892,10 @@ class Decoder(nn.Module):
             self.unets.append(one_unet)
             self.vaes.append(one_vae.copy_for_eval())
 
+        # determine from unets whether conditioning on text encoding is needed
+
+        self.condition_on_text_encodings = any([unet.cond_on_text_encodings for unet in self.unets])
+
         # create noise schedulers per unet
 
         if not exists(beta_schedule):
@@ -2291,6 +2327,6 @@ class DALLE2(nn.Module):
             images = list(map(self.to_pil, images.unbind(dim = 0)))
 
         if one_text:
-            return images[0]
+            return first(images)
 
         return images

dalle2_pytorch/train_configs.py

@@ -158,6 +158,8 @@ class UnetConfig(BaseModel):
     dim: int
     dim_mults: ListOrTuple(int)
     image_embed_dim: int = None
+    text_embed_dim: int = None
+    cond_on_text_encodings: bool = None
     cond_dim: int = None
     channels: int = 3
     attn_dim_head: int = 32
@@ -170,7 +172,6 @@ class DecoderConfig(BaseModel):
     unets: ListOrTuple(UnetConfig)
     image_size: int = None
     image_sizes: ListOrTuple(int) = None
-    condition_on_text_encodings: bool = False
     clip: Optional[AdapterConfig]   # The clip model to use if embeddings are not provided
     channels: int = 3
     timesteps: int = 1000
@@ -283,21 +284,27 @@ class TrainDecoderConfig(BaseModel):
     def check_has_embeddings(cls, values):
         # Makes sure that enough information is provided to get the embeddings specified for training
         data_config, decoder_config = values.get('data'), values.get('decoder')
-        if data_config is None or decoder_config is None:
+
+        if not exists(data_config) or not exists(decoder_config):
             # Then something else errored and we should just pass through
             return values
-        using_text_embeddings = decoder_config.condition_on_text_encodings
+
+        using_text_embeddings = any([unet.cond_on_text_encodings for unet in decoder_config.unets])
         using_clip = exists(decoder_config.clip)
         img_emb_url = data_config.img_embeddings_url
         text_emb_url = data_config.text_embeddings_url
+
         if using_text_embeddings:
             # Then we need some way to get the embeddings
-            assert using_clip or text_emb_url is not None, 'If condition_on_text_encodings is true, either clip or text_embeddings_url must be provided'
+            assert using_clip or exists(text_emb_url), 'If text conditioning, either clip or text_embeddings_url must be provided'
+
         if using_clip:
             if using_text_embeddings:
-                assert text_emb_url is None or img_emb_url is None, 'Loaded clip, but also provided text_embeddings_url and img_embeddings_url. This is redundant. Remove the clip model or the embeddings'
+                assert not exists(text_emb_url) or not exists(img_emb_url), 'Loaded clip, but also provided text_embeddings_url and img_embeddings_url. This is redundant. Remove the clip model or the text embeddings'
             else:
-                assert img_emb_url is None, 'Loaded clip, but also provided img_embeddings_url. This is redundant. Remove the clip model or the embeddings'
+                assert not exists(img_emb_url), 'Loaded clip, but also provided img_embeddings_url. This is redundant. Remove the clip model or the embeddings'
+
         if text_emb_url:
             assert using_text_embeddings, "Text embeddings are being loaded, but text embeddings are not being conditioned on. This will slow down the dataloader for no reason."
+
         return values

dalle2_pytorch/version.py

@@ -1 +1 @@
-__version__ = '0.12.0'
+__version__ = '0.14.1'

train_decoder.py

@@ -596,9 +596,11 @@ def initialize_training(config, config_path):
 
     has_img_embeddings = config.data.img_embeddings_url is not None
     has_text_embeddings = config.data.text_embeddings_url is not None
-    conditioning_on_text = config.decoder.condition_on_text_encodings
+    conditioning_on_text = any([unet.cond_on_text_encodings for unet in config.decoder.unets])
+
     has_clip_model = config.decoder.clip is not None
     data_source_string = ""
+
     if has_img_embeddings:
         data_source_string += "precomputed image embeddings"
     elif has_clip_model:
@@ -622,7 +624,7 @@ def initialize_training(config, config_path):
         inference_device=accelerator.device,
         load_config=config.load,
         evaluate_config=config.evaluate,
-        condition_on_text_encodings=config.decoder.condition_on_text_encodings,
+        condition_on_text_encodings=conditioning_on_text,
         **config.train.dict(),
     )