allow for decoder conditioning with the text encodings from CLIP, if it is passed in. use lazy linear to avoid researchers having to worry about text encoding dimensions, but remove later if it does not work well

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)
-
-```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)
+## Usage
 
 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 <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 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
 
@@ -109,7 +101,7 @@ clip = CLIP(
 unet = Unet(
     dim = 128,
     image_embed_dim = 512,
-    time_dim = 128,
+    cond_dim = 128,
     channels = 3,
     dim_mults=(1, 2, 4, 8)
 ).cuda()
@@ -272,7 +264,7 @@ loss.backward()
 unet = Unet(
     dim = 128,
     image_embed_dim = 512,
-    time_dim = 128,
+    cond_dim = 128,
     channels = 3,
     dim_mults=(1, 2, 4, 8)
 ).cuda()
@@ -284,7 +276,7 @@ decoder = Decoder(
     cond_drop_prob = 0.2
 ).cuda()
 
-loss = decoder(images)
+loss = decoder(images) # this can optionally be decoder(images, text) if you wish to condition on the text encodings as well, though it was hinted in the paper it didn't do much
 loss.backward()
 
 # do above for many steps
@@ -306,6 +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>
@@ -315,7 +319,7 @@ For the layperson, no worries, training will all be automated into a CLI tool, a
 - [x] finish off gaussian diffusion class for latent embedding - allow for prediction of epsilon
 - [x] add what was proposed in the paper, where DDPM objective for image latent embedding predicts x0 directly (reread vq-diffusion paper and get caught up on that line of work)
 - [x] make sure it works end to end to produce an output tensor, taking a single gradient step
-- [ ] augment unet so that it can also be conditioned on text encodings (although in paper they hinted this didn't make much a difference)
+- [x] augment unet so that it can also be conditioned on text encodings (although in paper they hinted this didn't make much a difference)
 - [ ] look into Jonathan Ho's cascading DDPM for the decoder, as that seems to be what they are using. get caught up on DDPM literature
 - [ ] 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

dalle2_pytorch/dalle2_pytorch.py

@@ -11,6 +11,8 @@ 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
@@ -116,14 +118,13 @@ class ChanRMSNorm(RMSNorm):
         inv_norm = torch.rsqrt(squared_sum + self.eps)
         return x * inv_norm * rearrange(self.gamma, 'c -> 1 c 1 1') * self.scale
 
-class PreNormResidual(nn.Module):
-    def __init__(self, dim, fn):
+class Residual(nn.Module):
+    def __init__(self, fn):
         super().__init__()
         self.fn = fn
-        self.norm = RMSNorm(dim)
 
     def forward(self, x, **kwargs):
-        return self.fn(self.norm(x), **kwargs) + x
+        return self.fn(x, **kwargs) + x
 
 # mlp
 
@@ -162,12 +163,21 @@ class MLP(nn.Module):
 
 # feedforward
 
-def FeedForward(dim, mult = 4, dropout = 0.):
+class SwiGLU(nn.Module):
+    """ used successfully in https://arxiv.org/abs/2204.0231 """
+    def forward(self, x):
+        x, gate = x.chunk(2, dim = -1)
+        return x * F.silu(gate)
+
+def FeedForward(dim, mult = 4, dropout = 0., post_activation_norm = False):
+    """ post-activation norm https://arxiv.org/abs/2110.09456 """
+
     inner_dim = int(mult * dim)
     return nn.Sequential(
         RMSNorm(dim),
-        nn.Linear(dim, inner_dim, bias = False),
-        nn.GELU(),
+        nn.Linear(dim, inner_dim * 2, bias = False),
+        SwiGLU(),
+        RMSNorm(inner_dim) if post_activation_norm else nn.Identity(),
         nn.Dropout(dropout),
         nn.Linear(inner_dim, dim, bias = False)
     )
@@ -229,6 +239,7 @@ class Attention(nn.Module):
 
         sim = sim - sim.amax(dim = -1, keepdim = True)
         attn = sim.softmax(dim = -1)
+        attn = self.dropout(attn)
 
         out = einsum('b h i j, b j d -> b h i d', attn, v)
 
@@ -285,17 +296,16 @@ class DiffusionPriorNetwork(nn.Module):
 
     def forward_with_cond_scale(
         self,
-        x,
         *args,
         cond_scale = 1.,
         **kwargs
     ):
-        logits = self.forward(x, *args, **kwargs)
+        logits = self.forward(*args, **kwargs)
 
         if cond_scale == 1:
             return logits
 
-        null_logits = self.forward(x, *args, cond_drop_prob = 1., **kwargs)
+        null_logits = self.forward(*args, cond_drop_prob = 1., **kwargs)
         return null_logits + (logits - null_logits) * cond_scale
 
     def forward(
@@ -315,8 +325,15 @@ 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
+            not_all_masked_out = mask.any(dim = -1)
+            mask = torch.cat((mask, rearrange(not_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')
@@ -554,6 +571,17 @@ def Upsample(dim):
 def Downsample(dim):
     return nn.Conv2d(dim, dim, 4, 2, 1)
 
+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 SinusoidalPosEmb(nn.Module):
     def __init__(self, dim):
         super().__init__()
@@ -581,10 +609,17 @@ class ConvNextBlock(nn.Module):
         super().__init__()
         need_projection = dim != dim_out
 
-        self.mlp = nn.Sequential(
-            nn.GELU(),
-            nn.Linear(cond_dim, dim)
-        ) if exists(cond_dim) else None
+        self.cross_attn = None
+
+        if exists(cond_dim):
+            self.cross_attn = EinopsToAndFrom(
+                'b c h w',
+                'b (h w) c',
+                CrossAttention(
+                    dim = dim,
+                    context_dim = cond_dim
+                )
+            )
 
         self.ds_conv = nn.Conv2d(dim, dim, 7, padding = 3, groups = dim)
 
@@ -601,21 +636,82 @@ class ConvNextBlock(nn.Module):
     def forward(self, x, cond = None):
         h = self.ds_conv(x)
 
-        if exists(self.mlp):
+        if exists(self.cross_attn):
             assert exists(cond)
-            condition = self.mlp(cond)
-            h = h + rearrange(condition, 'b c -> b c 1 1')
+            h = self.cross_attn(h, context = cond) + h
 
         h = self.net(h)
+
         return h + self.res_conv(x)
 
+class CrossAttention(nn.Module):
+    def __init__(
+        self,
+        dim,
+        *,
+        context_dim = None,
+        dim_head = 64,
+        heads = 8,
+        dropout = 0.,
+    ):
+        super().__init__()
+        self.scale = dim_head ** -0.5
+        self.heads = heads
+        inner_dim = dim_head * heads
+
+        context_dim = default(context_dim, dim)
+
+        self.norm = RMSNorm(dim)
+        self.norm_context = RMSNorm(context_dim)
+        self.dropout = nn.Dropout(dropout)
+
+        self.null_kv = nn.Parameter(torch.randn(2, dim_head))
+        self.to_q = nn.Linear(dim, inner_dim, bias = False)
+        self.to_kv = nn.Linear(context_dim, inner_dim * 2, bias = False)
+        self.to_out = nn.Linear(inner_dim, dim, bias = False)
+
+    def forward(self, x, context, mask = None):
+        b, n, device = *x.shape[:2], x.device
+
+        x = self.norm(x)
+        context = self.norm_context(context)
+
+        q, k, v = (self.to_q(x), *self.to_kv(context).chunk(2, dim = -1))
+
+        q, k, v = rearrange_many((q, k, v), 'b n (h d) -> b h n d', h = self.heads)
+
+        # add null key / value for classifier free guidance in prior net
+
+        nk, nv = repeat_many(self.null_kv.unbind(dim = -2), 'd -> b h 1 d', h = self.heads,  b = b)
+
+        k = torch.cat((nk, k), dim = -2)
+        v = torch.cat((nv, v), dim = -2)
+
+        q = q * self.scale
+
+        sim = einsum('b h i d, b h j d -> b h i j', q, k)
+        max_neg_value = -torch.finfo(sim.dtype).max
+
+        if exists(mask):
+            mask = F.pad(mask, (1, 0), value = True)
+            mask = rearrange(mask, 'b j -> b 1 1 j')
+            sim = sim.masked_fill(~mask, max_neg_value)
+
+        sim = sim - sim.amax(dim = -1, keepdim = True)
+        attn = sim.softmax(dim = -1)
+
+        out = einsum('b h i j, b h j d -> b h i d', attn, v)
+        out = rearrange(out, 'b h n d -> b n (h d)')
+        return self.to_out(out)
+
 class Unet(nn.Module):
     def __init__(
         self,
         dim,
         *,
         image_embed_dim,
-        time_dim = None,
+        cond_dim = None,
+        num_image_tokens = 4,
         out_dim = None,
         dim_mults=(1, 2, 4, 8),
         channels = 3,
@@ -626,18 +722,31 @@ class Unet(nn.Module):
         dims = [channels, *map(lambda m: dim * m, dim_mults)]
         in_out = list(zip(dims[:-1], dims[1:]))
 
-        time_dim = default(time_dim, dim)
+        # time, image embeddings, and optional text encoding
+
+        cond_dim = default(cond_dim, dim)
 
         self.time_mlp = nn.Sequential(
             SinusoidalPosEmb(dim),
             nn.Linear(dim, dim * 4),
             nn.GELU(),
-            nn.Linear(dim * 4, dim)
+            nn.Linear(dim * 4, cond_dim),
+            Rearrange('b d -> b 1 d')
         )
 
-        self.null_image_embed = nn.Parameter(torch.randn(image_embed_dim))
+        self.image_to_cond = nn.Sequential(
+            nn.Linear(image_embed_dim, cond_dim * num_image_tokens),
+            Rearrange('b (n d) -> b n d', n = num_image_tokens)
+        ) if image_embed_dim != cond_dim else nn.Identity()
 
-        cond_dim = time_dim + image_embed_dim
+        self.text_to_cond = nn.LazyLinear(cond_dim)
+
+        # for classifier free guidance
+
+        self.null_image_embed = nn.Parameter(torch.randn(1, num_image_tokens, cond_dim))
+        self.null_text_embed = nn.Parameter(torch.randn(1, 1, cond_dim))
+
+        # layers
 
         self.downs = nn.ModuleList([])
         self.ups = nn.ModuleList([])
@@ -647,7 +756,7 @@ class Unet(nn.Module):
             is_last = ind >= (num_resolutions - 1)
 
             self.downs.append(nn.ModuleList([
-                ConvNextBlock(dim_in, dim_out, cond_dim = cond_dim, norm = ind != 0),
+                ConvNextBlock(dim_in, dim_out, norm = ind != 0),
                 ConvNextBlock(dim_out, dim_out, cond_dim = cond_dim),
                 Downsample(dim_out) if not is_last else nn.Identity()
             ]))
@@ -655,7 +764,7 @@ class Unet(nn.Module):
         mid_dim = dims[-1]
 
         self.mid_block1 = ConvNextBlock(mid_dim, mid_dim, cond_dim = cond_dim)
-        self.mid_attn = EinopsToAndFrom('b c h w', 'b (h w) c', PreNormResidual(mid_dim, Attention(mid_dim)))
+        self.mid_attn = EinopsToAndFrom('b c h w', 'b (h w) c', Residual(Attention(mid_dim)))
         self.mid_block2 = ConvNextBlock(mid_dim, mid_dim, cond_dim = cond_dim)
 
         for ind, (dim_in, dim_out) in enumerate(reversed(in_out[1:])):
@@ -675,17 +784,16 @@ class Unet(nn.Module):
 
     def forward_with_cond_scale(
         self,
-        x,
         *args,
         cond_scale = 1.,
         **kwargs
     ):
-        logits = self.forward(x, *args, **kwargs)
+        logits = self.forward(*args, **kwargs)
 
         if cond_scale == 1:
             return logits
 
-        null_logits = self.forward(x, *args, cond_drop_prob = 1., **kwargs)
+        null_logits = self.forward(*args, cond_drop_prob = 1., **kwargs)
         return null_logits + (logits - null_logits) * cond_scale
 
     def forward(
@@ -698,37 +806,59 @@ class Unet(nn.Module):
         cond_drop_prob = 0.
     ):
         batch_size, device = x.shape[0], x.device
-        t = self.time_mlp(time)
+        time_tokens = self.time_mlp(time)
 
         cond_prob_mask = prob_mask_like((batch_size,), cond_drop_prob, device = device)
+        cond_prob_mask = rearrange(cond_prob_mask, 'b -> b 1 1')
 
         # mask out image embedding depending on condition dropout
         # for classifier free guidance
 
-        image_embed = torch.where(
-            rearrange(cond_prob_mask, 'b -> b 1'),
-            image_embed,
-            rearrange(self.null_image_embed, 'd -> 1 d')
+        image_tokens = self.image_to_cond(image_embed)
+
+        image_tokens = torch.where(
+            cond_prob_mask,
+            image_tokens,
+            self.null_image_embed
         )
 
-        t = torch.cat((t, image_embed), dim = -1)
+        # take care of text encodings (optional)
+
+        if exists(text_encodings):
+            text_tokens = self.text_to_cond(text_encodings)
+            text_tokens = torch.where(
+                cond_prob_mask,
+                text_tokens,
+                self.null_text_embed
+            )
+
+        # main conditioning tokens (c)
+
+        c = torch.cat((time_tokens, image_tokens), dim = -2)
+
+        # text and image conditioning tokens (mid_c)
+        # to save on compute, only do cross attention based conditioning on the inner most layers of the Unet
+
+        mid_c = c if not exists(text_encodings) else torch.cat((c, text_tokens), dim = -2)
+
+        # go through the layers of the unet, down and up
 
         hiddens = []
 
         for convnext, convnext2, downsample in self.downs:
-            x = convnext(x, t)
-            x = convnext2(x, t)
+            x = convnext(x, c)
+            x = convnext2(x, c)
             hiddens.append(x)
             x = downsample(x)
 
-        x = self.mid_block1(x, t)
+        x = self.mid_block1(x, mid_c)
         x = self.mid_attn(x)
-        x = self.mid_block2(x, t)
+        x = self.mid_block2(x, mid_c)
 
         for convnext, convnext2, upsample in self.ups:
             x = torch.cat((x, hiddens.pop()), dim=1)
-            x = convnext(x, t)
-            x = convnext2(x, t)
+            x = convnext(x, c)
+            x = convnext2(x, c)
             x = upsample(x)
 
         return self.final_conv(x)
@@ -789,6 +919,10 @@ class Decoder(nn.Module):
         self.register_buffer('posterior_mean_coef1', betas * torch.sqrt(alphas_cumprod_prev) / (1. - alphas_cumprod))
         self.register_buffer('posterior_mean_coef2', (1. - alphas_cumprod_prev) * torch.sqrt(alphas) / (1. - alphas_cumprod))
 
+    def get_text_encodings(self, text):
+        text_encodings = self.clip.text_transformer(text)
+        return text_encodings[:, 1:]
+
     def get_image_embed(self, image):
         image_encoding = self.clip.visual_transformer(image)
         image_cls = image_encoding[:, 0]
@@ -816,8 +950,8 @@ 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 = True, cond_scale = 1.):
-        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))
+    def p_mean_variance(self, x, t, image_embed, text_encodings = None, clip_denoised = True, cond_scale = 1.):
+        x_recon = self.predict_start_from_noise(x, t = t, noise = self.net.forward_with_cond_scale(x, t, image_embed = image_embed, text_encodings = text_encodings, cond_scale = cond_scale))
 
         if clip_denoised:
             x_recon.clamp_(-1., 1.)
@@ -826,31 +960,32 @@ class Decoder(nn.Module):
         return model_mean, posterior_variance, posterior_log_variance
 
     @torch.no_grad()
-    def p_sample(self, x, t, image_embed, cond_scale = 1., clip_denoised = True, repeat_noise = False):
+    def p_sample(self, x, t, image_embed, text_encodings = None, 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, cond_scale = cond_scale, clip_denoised = clip_denoised)
+        model_mean, _, model_log_variance = self.p_mean_variance(x = x, t = t, image_embed = image_embed, text_encodings = text_encodings, 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, cond_scale = 1):
+    def p_sample_loop(self, shape, image_embed, text_encodings = None, 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, cond_scale = cond_scale)
+            img = self.p_sample(img, torch.full((b,), i, device = device, dtype = torch.long), image_embed = image_embed, text_encodings = text_encodings, cond_scale = cond_scale)
         return img
 
     @torch.no_grad()
-    def sample(self, image_embed, cond_scale = 1.):
+    def sample(self, image_embed, text = None, 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, cond_scale = cond_scale)
+        text_encodings = self.get_text_encodings(text) if exists(text) else None
+        return self.p_sample_loop((batch_size, channels, image_size, image_size), image_embed = image_embed, text_encodings = text_encodings, cond_scale = cond_scale)
 
     def q_sample(self, x_start, t, noise=None):
         noise = default(noise, lambda: torch.randn_like(x_start))
@@ -860,7 +995,7 @@ class Decoder(nn.Module):
             extract(self.sqrt_one_minus_alphas_cumprod, t, x_start.shape) * noise
         )
 
-    def p_losses(self, x_start, t, *, image_embed, noise = None):
+    def p_losses(self, x_start, t, *, image_embed, text_encodings = None, noise = None):
         noise = default(noise, lambda: torch.randn_like(x_start))
 
         x_noisy = self.q_sample(x_start = x_start, t = t, noise = noise)
@@ -869,6 +1004,7 @@ class Decoder(nn.Module):
             x_noisy,
             t,
             image_embed = image_embed,
+            text_encodings = text_encodings,
             cond_drop_prob = self.cond_drop_prob
         )
 
@@ -881,14 +1017,16 @@ class Decoder(nn.Module):
 
         return loss
 
-    def forward(self, image):
+    def forward(self, image, text = None):
         b, device, img_size, = image.shape[0], image.device, self.image_size
         check_shape(image, 'b c h w', h = img_size, w = img_size, c = self.channels)
 
         times = torch.randint(0, self.num_timesteps, (b,), device = device, dtype = torch.long)
-        image_embed = self.get_image_embed(image)
 
-        loss = self.p_losses(image, times, image_embed = image_embed)
+        image_embed = self.get_image_embed(image)
+        text_encodings = self.get_text_encodings(text) if exists(text) else None
+
+        loss = self.p_losses(image, times, image_embed = image_embed, text_encodings = text_encodings)
         return loss
 
 # main class
@@ -904,11 +1042,12 @@ class DALLE2(nn.Module):
         super().__init__()
         assert isinstance(prior, DiffusionPrior)
         assert isinstance(decoder, Decoder)
-        self.prior = prior.eval()
-        self.decoder = decoder.eval()     
+        self.prior = prior
+        self.decoder = decoder
         self.prior_num_samples = prior_num_samples
 
     @torch.no_grad()
+    @eval_decorator
     def forward(
         self,
         text,

setup.py

@@ -10,7 +10,7 @@ setup(
       'dream = dalle2_pytorch.cli:dream'
     ],
   },
-  version = '0.0.8',
+  version = '0.0.14',
   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',