fix bug with classifier free guidance for prior network, even though it seems it may not be used

README.md

@@ -22,19 +22,11 @@ For all of you emailing me (there is a lot), the best way to contribute is throu
 $ pip install dalle2-pytorch
 ```
 
-## CLI Usage (work in progress)
+## Usage
-
-```bash
-$ dream 'sharing a sunset at the summit of mount everest with my dog'
-```
-
-Once built, images will be saved to the same directory the command is invoked
-
-## Training (for deep learning practitioners)
 
 To train DALLE-2 is a 3 step process, with the training of CLIP being the most important
 
-To train CLIP, you can either use `x-clip` package, or join the LAION discord, where a lot of replication efforts are already underway.
+To train CLIP, you can either use <a href="https://github.com/lucidrains/x-clip">x-clip</a> package, or join the LAION discord, where a lot of replication efforts are already <a href="https://github.com/mlfoundations/open_clip">underway</a>.
 
 This repository will demonstrate integration with `x-clip` for starters
 
@@ -136,12 +128,14 @@ loss.backward()
 # then it will learn to generate images based on the CLIP image embeddings
 ```
 
-Finally, the main contribution of the paper. The repository offers the diffusion prior network. It takes the CLIP text embeddings and tries to generate the CLIP image embeddings. Again, you will need the trained CLIP fron the first step
+Finally, the main contribution of the paper. The repository offers the diffusion prior network. It takes the CLIP text embeddings and tries to generate the CLIP image embeddings. Again, you will need the trained CLIP from the first step
 
 ```python
 import torch
 from dalle2_pytorch import DiffusionPriorNetwork, DiffusionPrior, CLIP
 
+# get trained CLIP from step one
+
 clip = CLIP(
     dim_text = 512,
     dim_image = 512,
@@ -160,7 +154,6 @@ clip = CLIP(
 
 prior_network = DiffusionPriorNetwork(
     dim = 512,
-    num_timesteps = 100,
     depth = 6,
     dim_head = 64,
     heads = 8
@@ -199,7 +192,7 @@ dalle2 = DALLE2(
     decoder = decoder
 )
 
-# send the text as a string if you want to use the simple tokenizer from DALL-E1
+# send the text as a string if you want to use the simple tokenizer from DALLE v1
 # or you can do it as token ids, if you have your own tokenizer
 
 texts = ['glistening morning dew on a flower petal']
@@ -249,7 +242,6 @@ loss.backward()
 
 prior_network = DiffusionPriorNetwork(
     dim = 512,
-    num_timesteps = 100,
     depth = 6,
     dim_head = 64,
     heads = 8
@@ -294,7 +286,10 @@ dalle2 = DALLE2(
     decoder = decoder
 )
 
-images = dalle2(['cute puppy chasing after a squirrel'])
+images = dalle2(
+    ['cute puppy chasing after a squirrel'],
+    cond_scale = 2. # classifier free guidance strength (> 1 would strengthen the condition)
+)
 
 # save your image
 ```
@@ -303,6 +298,18 @@ Everything in this readme should run without error
 
 For the layperson, no worries, training will all be automated into a CLI tool, at least for small scale training.
 
+## CLI Usage (work in progress)
+
+```bash
+$ dream 'sharing a sunset at the summit of mount everest with my dog'
+```
+
+Once built, images will be saved to the same directory the command is invoked
+
+## Training wrapper (wip)
+
+Offer training wrappers
+
 ## Training CLI (wip)
 
 <a href="https://github.com/lucidrains/stylegan2-pytorch">template</a>
@@ -317,6 +324,7 @@ For the layperson, no worries, training will all be automated into a CLI tool, a
 - [ ] figure out all the current bag of tricks needed to make DDPMs great (starting with the blur trick mentioned in paper)
 - [ ] train on a toy task, offer in colab
 - [ ] add attention to unet - apply some personal tricks with efficient attention
+- [ ] figure out the big idea behind latent diffusion and what can be ported over
 
 ## Citations
 

dalle2_pytorch/dalle2_pytorch.py

@@ -7,9 +7,12 @@ import torch.nn.functional as F
 from torch import nn, einsum
 
 from einops import rearrange, repeat
+from einops.layers.torch import Rearrange
 from einops_exts import rearrange_many, repeat_many, check_shape
 from einops_exts.torch import EinopsToAndFrom
 
+from kornia.filters import filter2d
+
 from dalle2_pytorch.tokenizer import tokenizer
 
 # use x-clip
@@ -124,6 +127,43 @@ class PreNormResidual(nn.Module):
     def forward(self, x, **kwargs):
         return self.fn(self.norm(x), **kwargs) + x
 
+# mlp
+
+class MLP(nn.Module):
+    def __init__(
+        self,
+        dim_in,
+        dim_out,
+        *,
+        expansion_factor = 2.,
+        depth = 2,
+        norm = False,
+    ):
+        super().__init__()
+        hidden_dim = int(expansion_factor * dim_out)
+        norm_fn = lambda: nn.LayerNorm(hidden_dim) if norm else nn.Identity()
+
+        layers = [nn.Sequential(
+            nn.Linear(dim_in, hidden_dim),
+            nn.SiLU(),
+            norm_fn()
+        )]
+
+        for _ in range(depth - 1):
+            layers.append(nn.Sequential(
+                nn.Linear(hidden_dim, hidden_dim),
+                nn.SiLU(),
+                norm_fn()
+            ))
+
+        layers.append(nn.Linear(hidden_dim, dim_out))
+        self.net = nn.Sequential(*layers)
+
+    def forward(self, x):
+        return self.net(x.float())
+
+# feedforward
+
 def FeedForward(dim, mult = 4, dropout = 0.):
     inner_dim = int(mult * dim)
     return nn.Sequential(
@@ -134,6 +174,8 @@ def FeedForward(dim, mult = 4, dropout = 0.):
         nn.Linear(inner_dim, dim, bias = False)
     )
 
+# attention
+
 class Attention(nn.Module):
     def __init__(
         self,
@@ -235,26 +277,26 @@ class DiffusionPriorNetwork(nn.Module):
     def __init__(
         self,
         dim,
-        num_timesteps = 1000,
+        num_timesteps = None,
         **kwargs
     ):
         super().__init__()
-        self.time_embeddings = nn.Embedding(num_timesteps, dim)  # also offer a continuous version of timestep embeddings, with a 2 layer MLP
+        self.time_embeddings = nn.Embedding(num_timesteps, dim) if exists(num_timesteps) else nn.Sequential(Rearrange('b -> b 1'), MLP(1, dim)) # also offer a continuous version of timestep embeddings, with a 2 layer MLP
         self.learned_query = nn.Parameter(torch.randn(dim))
         self.causal_transformer = CausalTransformer(dim = dim, **kwargs)
 
     def forward_with_cond_scale(
         self,
-        x,
+        *args,
-        *,
         cond_scale = 1.,
         **kwargs
     ):
-        if cond_scale == 1:
+        logits = self.forward(*args, **kwargs)
-            return self.forward(x, **kwargs)
 
-        logits = self.forward(x, **kwargs)
+        if cond_scale == 1:
-        null_logits = self.forward(x, cond_drop_prob = 1., **kwargs)
+            return logits
+
+        null_logits = self.forward(*args, cond_drop_prob = 1., **kwargs)
         return null_logits + (logits - null_logits) * cond_scale
 
     def forward(
@@ -274,8 +316,15 @@ class DiffusionPriorNetwork(nn.Module):
 
         text_embed, image_embed = rearrange_many((text_embed, image_embed), 'b d -> b 1 d')
 
+        # whether text embedding is used for conditioning depends on whether text encodings are available for attention (for classifier free guidance, even though it seems from the paper it was not used in the prior ddpm, as the objective is different)
+        # but let's just do it right
+
         if exists(mask):
-            mask = F.pad(mask, (0, 3), value = True) # extend mask for text embedding, noised image embedding, time step embedding, and learned query
+            all_masked_out = mask.any(dim = -1)
+            mask = torch.cat((mask, rearrange(all_masked_out, 'b -> b 1')), dim = 1)
+
+        if exists(mask):
+            mask = F.pad(mask, (0, 2), value = True) # extend mask for text embedding, noised image embedding, time step embedding, and learned query
 
         time_embed = self.time_embeddings(diffusion_timesteps)
         time_embed = rearrange(time_embed, 'b d -> b 1 d')
@@ -634,16 +683,16 @@ class Unet(nn.Module):
 
     def forward_with_cond_scale(
         self,
-        x,
+        *args,
-        *,
         cond_scale = 1.,
         **kwargs
     ):
-        if cond_scale == 1:
+        logits = self.forward(*args, **kwargs)
-            return self.forward(x, **kwargs)
 
-        logits = self.forward(x, **kwargs)
+        if cond_scale == 1:
-        null_logits = self.forward(x, cond_drop_prob = 1., **kwargs)
+            return logits
+
+        null_logits = self.forward(*args, cond_drop_prob = 1., **kwargs)
         return null_logits + (logits - null_logits) * cond_scale
 
     def forward(
@@ -691,6 +740,17 @@ class Unet(nn.Module):
 
         return self.final_conv(x)
 
+class Blur(nn.Module):
+    def __init__(self):
+        super().__init__()
+        filt = torch.Tensor([1, 2, 1])
+        self.register_buffer('filt', filt)
+
+    def forward(self, x):
+        filt = self.filt
+        filt = rearrange(filt, '... j -> ... 1 j') * rearrange(flit, '... i -> ... i 1')
+        return filter2d(x, filt, normalized = True)
+
 class Decoder(nn.Module):
     def __init__(
         self,
@@ -774,8 +834,8 @@ class Decoder(nn.Module):
         posterior_log_variance_clipped = extract(self.posterior_log_variance_clipped, t, x_t.shape)
         return posterior_mean, posterior_variance, posterior_log_variance_clipped
 
-    def p_mean_variance(self, x, t, image_embed, clip_denoised: bool):
+    def p_mean_variance(self, x, t, image_embed, clip_denoised = True, cond_scale = 1.):
-        x_recon = self.predict_start_from_noise(x, t = t, noise = self.net(x, t, image_embed = image_embed))
+        x_recon = self.predict_start_from_noise(x, t = t, noise = self.net.forward_with_cond_scale(x, t, image_embed = image_embed, cond_scale = cond_scale))
 
         if clip_denoised:
             x_recon.clamp_(-1., 1.)
@@ -784,31 +844,31 @@ class Decoder(nn.Module):
         return model_mean, posterior_variance, posterior_log_variance
 
     @torch.no_grad()
-    def p_sample(self, x, t, image_embed, clip_denoised = True, repeat_noise = False):
+    def p_sample(self, x, t, image_embed, cond_scale = 1., clip_denoised = True, repeat_noise = False):
         b, *_, device = *x.shape, x.device
-        model_mean, _, model_log_variance = self.p_mean_variance(x = x, t = t, image_embed = image_embed, clip_denoised = clip_denoised)
+        model_mean, _, model_log_variance = self.p_mean_variance(x = x, t = t, image_embed = image_embed, cond_scale = cond_scale, clip_denoised = clip_denoised)
         noise = noise_like(x.shape, device, repeat_noise)
         # no noise when t == 0
         nonzero_mask = (1 - (t == 0).float()).reshape(b, *((1,) * (len(x.shape) - 1)))
         return model_mean + nonzero_mask * (0.5 * model_log_variance).exp() * noise
 
     @torch.no_grad()
-    def p_sample_loop(self, shape, image_embed):
+    def p_sample_loop(self, shape, image_embed, cond_scale = 1):
         device = self.betas.device
 
         b = shape[0]
         img = torch.randn(shape, device=device)
 
         for i in tqdm(reversed(range(0, self.num_timesteps)), desc='sampling loop time step', total=self.num_timesteps):
-            img = self.p_sample(img, torch.full((b,), i, device = device, dtype = torch.long), image_embed = image_embed)
+            img = self.p_sample(img, torch.full((b,), i, device = device, dtype = torch.long), image_embed = image_embed, cond_scale = cond_scale)
         return img
 
     @torch.no_grad()
-    def sample(self, image_embed):
+    def sample(self, image_embed, cond_scale = 1.):
         batch_size = image_embed.shape[0]
         image_size = self.image_size
         channels = self.channels
-        return self.p_sample_loop((batch_size, channels, image_size, image_size), image_embed = image_embed)
+        return self.p_sample_loop((batch_size, channels, image_size, image_size), image_embed = image_embed, cond_scale = cond_scale)
 
     def q_sample(self, x_start, t, noise=None):
         noise = default(noise, lambda: torch.randn_like(x_start))
@@ -869,7 +929,8 @@ class DALLE2(nn.Module):
     @torch.no_grad()
     def forward(
         self,
-        text
+        text,
+        cond_scale = 1.
     ):
         device = next(self.parameters()).device
 
@@ -877,7 +938,6 @@ class DALLE2(nn.Module):
             text = [text] if not isinstance(text, (list, tuple)) else text
             text = tokenizer.tokenize(text).to(device)
 
-        print(text.shape, type(text))
         image_embed = self.prior.sample(text, num_samples_per_batch = self.prior_num_samples)
-        images = self.decoder.sample(image_embed)
+        images = self.decoder.sample(image_embed, cond_scale = cond_scale)
         return images

setup.py

@@ -10,7 +10,7 @@ setup(
       'dream = dalle2_pytorch.cli:dream'
     ],
   },
-  version = '0.0.5',
+  version = '0.0.9',
   license='MIT',
   description = 'DALL-E 2',
   author = 'Phil Wang',
@@ -25,6 +25,7 @@ setup(
     'click',
     'einops>=0.4',
     'einops-exts>=0.0.3',
+    'kornia>=0.5.4',
     'pillow',
     'torch>=1.10',
     'torchvision',