Upload inference.py
Browse files- inference.py +670 -0
inference.py
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| 1 |
+
"""
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| 2 |
+
ShellD (Shell Diffusion) - Standalone Inference
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| 3 |
+
================================================
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| 4 |
+
Generate 256x256 images from text prompts using a pre-trained ShellD model.
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| 5 |
+
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| 6 |
+
This file is fully self-contained β it does NOT import from train.py.
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| 7 |
+
It duplicates only the architecture classes needed for inference, with all
|
| 8 |
+
training-specific code (dataset, optimizers, VAE pretraining, git cloning, etc.) removed.
|
| 9 |
+
|
| 10 |
+
Usage (load from Hugging Face):
|
| 11 |
+
from inference import ShellDInference
|
| 12 |
+
|
| 13 |
+
pipe = ShellDInference("FlameF0X/ShellD")
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| 14 |
+
img = pipe.generate("a mountain lake at sunset")
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| 15 |
+
img.save("output.png")
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| 16 |
+
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| 17 |
+
Usage (load from local directory):
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| 18 |
+
pipe = ShellDInference("./ShellD_model")
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| 19 |
+
"""
|
| 20 |
+
|
| 21 |
+
import json
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| 22 |
+
import math
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| 23 |
+
from dataclasses import dataclass, asdict
|
| 24 |
+
from pathlib import Path
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| 25 |
+
from typing import Dict, Any, List, Optional, Tuple
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| 26 |
+
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| 27 |
+
import torch
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| 28 |
+
import torch.nn as nn
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| 29 |
+
from huggingface_hub import snapshot_download
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| 30 |
+
import torch.nn.functional as F
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| 31 |
+
from safetensors.torch import load_file
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| 32 |
+
from sentence_transformers import SentenceTransformer
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| 33 |
+
from PIL import Image
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| 34 |
+
import numpy as np
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| 35 |
+
|
| 36 |
+
|
| 37 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 38 |
+
# Config
|
| 39 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 40 |
+
|
| 41 |
+
@dataclass
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| 42 |
+
class ShellDConfig:
|
| 43 |
+
"""Model hyperparameters. Must match the saved config.json."""
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| 44 |
+
image_size: int = 256
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| 45 |
+
latent_dim: int = 16
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| 46 |
+
ae_hidden_dim: int = 64
|
| 47 |
+
ae_num_blocks: int = 3
|
| 48 |
+
hidden_dim: int = 256
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| 49 |
+
num_hidden_layers: int = 12
|
| 50 |
+
num_heads: int = 8
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| 51 |
+
patch_size: int = 4
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| 52 |
+
text_encoder_name: str = "./all-MiniLM-L6-v2"
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| 53 |
+
text_encoder_dim: int = 384
|
| 54 |
+
num_timesteps: int = 1000
|
| 55 |
+
beta_start: float = 1e-4
|
| 56 |
+
beta_end: float = 0.02
|
| 57 |
+
model_name: str = "ShellD"
|
| 58 |
+
|
| 59 |
+
@classmethod
|
| 60 |
+
def from_json(cls, path: str) -> "ShellDConfig":
|
| 61 |
+
with open(path) as f:
|
| 62 |
+
d = json.load(f)
|
| 63 |
+
# Strip keys starting with "_"
|
| 64 |
+
d = {k: v for k, v in d.items() if not k.startswith("_")}
|
| 65 |
+
return cls(**d)
|
| 66 |
+
|
| 67 |
+
|
| 68 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 69 |
+
# VAE β Encoder / Decoder
|
| 70 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 71 |
+
|
| 72 |
+
class ResidualBlock(nn.Module):
|
| 73 |
+
def __init__(self, in_ch: int, out_ch: int):
|
| 74 |
+
super().__init__()
|
| 75 |
+
self.conv1 = nn.Conv2d(in_ch, out_ch, 3, padding=1)
|
| 76 |
+
self.norm1 = nn.GroupNorm(8, out_ch)
|
| 77 |
+
self.conv2 = nn.Conv2d(out_ch, out_ch, 3, padding=1)
|
| 78 |
+
self.norm2 = nn.GroupNorm(8, out_ch)
|
| 79 |
+
self.skip = nn.Conv2d(in_ch, out_ch, 1) if in_ch != out_ch else nn.Identity()
|
| 80 |
+
|
| 81 |
+
def forward(self, x: torch.Tensor) -> torch.Tensor:
|
| 82 |
+
residual = self.skip(x)
|
| 83 |
+
x = F.silu(self.norm1(self.conv1(x)))
|
| 84 |
+
x = self.norm2(self.conv2(x))
|
| 85 |
+
return F.silu(x + residual)
|
| 86 |
+
|
| 87 |
+
|
| 88 |
+
class Encoder(nn.Module):
|
| 89 |
+
def __init__(self, cfg: ShellDConfig):
|
| 90 |
+
super().__init__()
|
| 91 |
+
self.cfg = cfg
|
| 92 |
+
self.init_conv = nn.Conv2d(3, cfg.ae_hidden_dim, 3, padding=1)
|
| 93 |
+
|
| 94 |
+
blocks = []
|
| 95 |
+
ch = cfg.ae_hidden_dim
|
| 96 |
+
for _ in range(cfg.ae_num_blocks):
|
| 97 |
+
out_ch = min(ch * 2, 256)
|
| 98 |
+
blocks.append(
|
| 99 |
+
nn.Sequential(
|
| 100 |
+
ResidualBlock(ch, out_ch),
|
| 101 |
+
ResidualBlock(out_ch, out_ch),
|
| 102 |
+
nn.Conv2d(out_ch, out_ch, 4, stride=2, padding=1), # downsample
|
| 103 |
+
)
|
| 104 |
+
)
|
| 105 |
+
ch = out_ch
|
| 106 |
+
self.down_blocks = nn.ModuleList(blocks)
|
| 107 |
+
|
| 108 |
+
self.mid = nn.Sequential(
|
| 109 |
+
ResidualBlock(ch, ch),
|
| 110 |
+
ResidualBlock(ch, ch),
|
| 111 |
+
)
|
| 112 |
+
self.out_conv = nn.Conv2d(ch, cfg.latent_dim * 2, 3, padding=1)
|
| 113 |
+
|
| 114 |
+
def forward(self, x: torch.Tensor) -> Tuple[torch.Tensor, torch.Tensor]:
|
| 115 |
+
x = self.init_conv(x)
|
| 116 |
+
for block in self.down_blocks:
|
| 117 |
+
x = block(x)
|
| 118 |
+
x = self.mid(x)
|
| 119 |
+
x = self.out_conv(x)
|
| 120 |
+
mean, logvar = x.chunk(2, dim=1)
|
| 121 |
+
return mean, logvar
|
| 122 |
+
|
| 123 |
+
|
| 124 |
+
class Decoder(nn.Module):
|
| 125 |
+
def __init__(self, cfg: ShellDConfig):
|
| 126 |
+
super().__init__()
|
| 127 |
+
self.cfg = cfg
|
| 128 |
+
ch = cfg.ae_hidden_dim * (2 ** cfg.ae_num_blocks)
|
| 129 |
+
self.init_conv = nn.Conv2d(cfg.latent_dim, ch, 3, padding=1)
|
| 130 |
+
|
| 131 |
+
self.mid = nn.Sequential(
|
| 132 |
+
ResidualBlock(ch, ch),
|
| 133 |
+
ResidualBlock(ch, ch),
|
| 134 |
+
)
|
| 135 |
+
|
| 136 |
+
up_blocks = []
|
| 137 |
+
for _ in range(cfg.ae_num_blocks):
|
| 138 |
+
out_ch = ch // 2
|
| 139 |
+
up_blocks.append(
|
| 140 |
+
nn.Sequential(
|
| 141 |
+
ResidualBlock(ch, out_ch),
|
| 142 |
+
ResidualBlock(out_ch, out_ch),
|
| 143 |
+
nn.Upsample(scale_factor=2, mode="nearest"),
|
| 144 |
+
)
|
| 145 |
+
)
|
| 146 |
+
ch = out_ch
|
| 147 |
+
self.up_blocks = nn.ModuleList(up_blocks)
|
| 148 |
+
|
| 149 |
+
self.out_conv = nn.Sequential(
|
| 150 |
+
ResidualBlock(ch, ch),
|
| 151 |
+
nn.Conv2d(ch, 3, 3, padding=1),
|
| 152 |
+
nn.Sigmoid(),
|
| 153 |
+
)
|
| 154 |
+
|
| 155 |
+
def forward(self, z: torch.Tensor) -> torch.Tensor:
|
| 156 |
+
x = self.init_conv(z)
|
| 157 |
+
x = self.mid(x)
|
| 158 |
+
for block in self.up_blocks:
|
| 159 |
+
x = block(x)
|
| 160 |
+
return self.out_conv(x)
|
| 161 |
+
|
| 162 |
+
|
| 163 |
+
class VAE(nn.Module):
|
| 164 |
+
def __init__(self, cfg: ShellDConfig):
|
| 165 |
+
super().__init__()
|
| 166 |
+
self.cfg = cfg
|
| 167 |
+
self.encoder = Encoder(cfg)
|
| 168 |
+
self.decoder = Decoder(cfg)
|
| 169 |
+
|
| 170 |
+
def encode(self, x: torch.Tensor) -> torch.Tensor:
|
| 171 |
+
mean, logvar = self.encoder(x)
|
| 172 |
+
logvar = logvar.clamp(-10.0, 10.0)
|
| 173 |
+
std = torch.exp(0.5 * logvar)
|
| 174 |
+
eps = torch.randn_like(std)
|
| 175 |
+
return mean + eps * std
|
| 176 |
+
|
| 177 |
+
def decode(self, z: torch.Tensor) -> torch.Tensor:
|
| 178 |
+
return self.decoder(z)
|
| 179 |
+
|
| 180 |
+
def forward(self, x: torch.Tensor):
|
| 181 |
+
"""Full forward (used only for training; included for completeness)."""
|
| 182 |
+
mean, logvar = self.encoder(x)
|
| 183 |
+
logvar = logvar.clamp(-10.0, 10.0)
|
| 184 |
+
std = torch.exp(0.5 * logvar)
|
| 185 |
+
eps = torch.randn_like(std)
|
| 186 |
+
z = mean + eps * std
|
| 187 |
+
return self.decode(z)
|
| 188 |
+
|
| 189 |
+
|
| 190 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 191 |
+
# DiT Backbone
|
| 192 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 193 |
+
|
| 194 |
+
class PatchEmbed(nn.Module):
|
| 195 |
+
def __init__(self, cfg: ShellDConfig):
|
| 196 |
+
super().__init__()
|
| 197 |
+
self.cfg = cfg
|
| 198 |
+
self.latent_size = cfg.image_size // (2 ** cfg.ae_num_blocks)
|
| 199 |
+
self.num_patches_1d = self.latent_size // cfg.patch_size
|
| 200 |
+
self.num_patches = self.num_patches_1d ** 2
|
| 201 |
+
self.patch_dim = cfg.latent_dim * (cfg.patch_size ** 2)
|
| 202 |
+
self.proj = nn.Linear(self.patch_dim, cfg.hidden_dim)
|
| 203 |
+
|
| 204 |
+
def forward(self, z: torch.Tensor) -> torch.Tensor:
|
| 205 |
+
B, C, H, W = z.shape
|
| 206 |
+
ps = self.cfg.patch_size
|
| 207 |
+
n = self.num_patches_1d
|
| 208 |
+
z = z.reshape(B, C, n, ps, n, ps)
|
| 209 |
+
z = z.permute(0, 2, 4, 1, 3, 5).reshape(B, self.num_patches, self.patch_dim)
|
| 210 |
+
return self.proj(z)
|
| 211 |
+
|
| 212 |
+
|
| 213 |
+
class DiTBlock(nn.Module):
|
| 214 |
+
def __init__(self, cfg: ShellDConfig):
|
| 215 |
+
super().__init__()
|
| 216 |
+
dim = cfg.hidden_dim
|
| 217 |
+
self.norm1 = nn.LayerNorm(dim)
|
| 218 |
+
self.attn = nn.MultiheadAttention(dim, cfg.num_heads, batch_first=True)
|
| 219 |
+
self.norm_cross = nn.LayerNorm(dim)
|
| 220 |
+
self.cross_attn = nn.MultiheadAttention(dim, cfg.num_heads, batch_first=True)
|
| 221 |
+
self.text_proj = nn.Linear(cfg.text_encoder_dim, dim)
|
| 222 |
+
self.norm2 = nn.LayerNorm(dim)
|
| 223 |
+
self.mlp = nn.Sequential(
|
| 224 |
+
nn.Linear(dim, dim * 4),
|
| 225 |
+
nn.GELU(),
|
| 226 |
+
nn.Linear(dim * 4, dim),
|
| 227 |
+
)
|
| 228 |
+
self.timestep_mlp = nn.Sequential(
|
| 229 |
+
nn.Linear(dim, dim * 4),
|
| 230 |
+
nn.SiLU(),
|
| 231 |
+
nn.Linear(dim * 4, dim),
|
| 232 |
+
)
|
| 233 |
+
|
| 234 |
+
def forward(self, x: torch.Tensor, text_emb: torch.Tensor, t_emb: torch.Tensor):
|
| 235 |
+
# Self-attention
|
| 236 |
+
h = self.norm1(x)
|
| 237 |
+
attn_out, _ = self.attn(h, h, h)
|
| 238 |
+
x = x + attn_out
|
| 239 |
+
# Cross-attention with text
|
| 240 |
+
text_proj = self.text_proj(text_emb)
|
| 241 |
+
h = self.norm_cross(x)
|
| 242 |
+
cross_out, _ = self.cross_attn(h, text_proj, text_proj)
|
| 243 |
+
x = x + cross_out
|
| 244 |
+
# Timestep conditioning
|
| 245 |
+
t_proj = self.timestep_mlp(t_emb)
|
| 246 |
+
x = x + t_proj.unsqueeze(1)
|
| 247 |
+
# MLP
|
| 248 |
+
h = self.norm2(x)
|
| 249 |
+
x = x + self.mlp(h)
|
| 250 |
+
return x
|
| 251 |
+
|
| 252 |
+
|
| 253 |
+
class DiT(nn.Module):
|
| 254 |
+
def __init__(self, cfg: ShellDConfig):
|
| 255 |
+
super().__init__()
|
| 256 |
+
self.cfg = cfg
|
| 257 |
+
self.latent_size = cfg.image_size // (2 ** cfg.ae_num_blocks)
|
| 258 |
+
self.num_patches_1d = self.latent_size // cfg.patch_size
|
| 259 |
+
self.num_patches = self.num_patches_1d ** 2
|
| 260 |
+
|
| 261 |
+
self.patch_embed = PatchEmbed(cfg)
|
| 262 |
+
self.pos_embed = nn.Parameter(torch.randn(1, self.num_patches, cfg.hidden_dim))
|
| 263 |
+
self.blocks = nn.ModuleList([DiTBlock(cfg) for _ in range(cfg.num_hidden_layers)])
|
| 264 |
+
self.norm = nn.LayerNorm(cfg.hidden_dim)
|
| 265 |
+
self.out_proj = nn.Linear(cfg.hidden_dim, cfg.latent_dim * (cfg.patch_size ** 2))
|
| 266 |
+
|
| 267 |
+
self.time_mlp = nn.Sequential(
|
| 268 |
+
nn.Linear(cfg.hidden_dim, cfg.hidden_dim * 4),
|
| 269 |
+
nn.SiLU(),
|
| 270 |
+
nn.Linear(cfg.hidden_dim * 4, cfg.hidden_dim),
|
| 271 |
+
)
|
| 272 |
+
|
| 273 |
+
@staticmethod
|
| 274 |
+
def timestep_embedding(t: torch.Tensor, dim: int, max_period: int = 10000):
|
| 275 |
+
half = dim // 2
|
| 276 |
+
freqs = torch.exp(
|
| 277 |
+
-math.log(max_period) * torch.arange(0, half, dtype=torch.float32) / half
|
| 278 |
+
).to(t.device)
|
| 279 |
+
args = t[:, None].float() * freqs[None]
|
| 280 |
+
emb = torch.cat([torch.cos(args), torch.sin(args)], dim=-1)
|
| 281 |
+
if dim % 2 == 1:
|
| 282 |
+
emb = torch.cat([emb, torch.zeros_like(emb[:, :1])], dim=-1)
|
| 283 |
+
return emb
|
| 284 |
+
|
| 285 |
+
def forward(self, z: torch.Tensor, text_emb: torch.Tensor, t: torch.Tensor):
|
| 286 |
+
B = z.shape[0]
|
| 287 |
+
dim = self.cfg.hidden_dim
|
| 288 |
+
t_emb = self.timestep_embedding(t, dim)
|
| 289 |
+
t_emb = self.time_mlp(t_emb)
|
| 290 |
+
|
| 291 |
+
x = self.patch_embed(z)
|
| 292 |
+
x = x + self.pos_embed
|
| 293 |
+
|
| 294 |
+
for blk in self.blocks:
|
| 295 |
+
x = blk(x, text_emb, t_emb)
|
| 296 |
+
|
| 297 |
+
x = self.norm(x)
|
| 298 |
+
x = self.out_proj(x)
|
| 299 |
+
|
| 300 |
+
ps = self.cfg.patch_size
|
| 301 |
+
H = W = self.latent_size
|
| 302 |
+
n = self.num_patches_1d
|
| 303 |
+
x = x.reshape(B, n, n, self.cfg.latent_dim, ps, ps)
|
| 304 |
+
x = x.permute(0, 3, 1, 4, 2, 5).reshape(B, self.cfg.latent_dim, H, W)
|
| 305 |
+
return x
|
| 306 |
+
|
| 307 |
+
|
| 308 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 309 |
+
# Full ShellD Model (Inference-only)
|
| 310 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 311 |
+
|
| 312 |
+
class ShellDModel(nn.Module):
|
| 313 |
+
"""ShellD model for inference. Minimal β no training helpers."""
|
| 314 |
+
|
| 315 |
+
def __init__(self, cfg: ShellDConfig):
|
| 316 |
+
super().__init__()
|
| 317 |
+
self.cfg = cfg
|
| 318 |
+
self.vae = VAE(cfg)
|
| 319 |
+
self.dit = DiT(cfg)
|
| 320 |
+
self.text_encoder = None # loaded separately
|
| 321 |
+
|
| 322 |
+
def encode_text(self, prompts: List[str], device: torch.device) -> torch.Tensor:
|
| 323 |
+
assert self.text_encoder is not None, "Text encoder not loaded"
|
| 324 |
+
with torch.no_grad():
|
| 325 |
+
emb = self.text_encoder.encode(prompts, convert_to_tensor=True)
|
| 326 |
+
return emb.to(device).unsqueeze(1) # [B, 1, 384]
|
| 327 |
+
|
| 328 |
+
def forward(self, z: torch.Tensor, text_emb: torch.Tensor, t: torch.Tensor) -> torch.Tensor:
|
| 329 |
+
"""Predict the noise at timestep t given noisy latent z and text."""
|
| 330 |
+
return self.dit(z, text_emb, t)
|
| 331 |
+
|
| 332 |
+
|
| 333 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 334 |
+
# Diffusion Schedule (Reverse Process Only)
|
| 335 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 336 |
+
|
| 337 |
+
class DiffusionSchedule:
|
| 338 |
+
"""DDPM schedule for the reverse (denoising) process."""
|
| 339 |
+
|
| 340 |
+
def __init__(self, cfg: ShellDConfig, device: torch.device):
|
| 341 |
+
betas = torch.linspace(cfg.beta_start, cfg.beta_end, cfg.num_timesteps, device=device)
|
| 342 |
+
alphas = 1.0 - betas
|
| 343 |
+
alphas_cumprod = torch.cumprod(alphas, dim=0)
|
| 344 |
+
|
| 345 |
+
self.betas = betas
|
| 346 |
+
self.alphas = alphas
|
| 347 |
+
self.alphas_cumprod = alphas_cumprod
|
| 348 |
+
self.sqrt_alphas_cumprod = alphas_cumprod.sqrt()
|
| 349 |
+
self.sqrt_one_minus_alphas_cumprod = (1.0 - alphas_cumprod).sqrt()
|
| 350 |
+
|
| 351 |
+
@torch.no_grad()
|
| 352 |
+
def sample(
|
| 353 |
+
self,
|
| 354 |
+
model: ShellDModel,
|
| 355 |
+
text_emb: torch.Tensor,
|
| 356 |
+
num_steps: Optional[int] = None,
|
| 357 |
+
cfg_scale: float = 3.0,
|
| 358 |
+
seed: Optional[int] = None,
|
| 359 |
+
) -> torch.Tensor:
|
| 360 |
+
"""
|
| 361 |
+
DDPM reverse sampling with optional classifier-free guidance.
|
| 362 |
+
|
| 363 |
+
Args:
|
| 364 |
+
model: The ShellD model.
|
| 365 |
+
text_emb: Text embedding [B, 1, 384].
|
| 366 |
+
num_steps: Number of denoising steps (default: cfg.num_timesteps).
|
| 367 |
+
cfg_scale: Classifier-free guidance scale. 1.0 = no guidance.
|
| 368 |
+
seed: Optional random seed for reproducibility.
|
| 369 |
+
|
| 370 |
+
Returns:
|
| 371 |
+
Denoised latent tensor [B, latent_dim, H', W'].
|
| 372 |
+
"""
|
| 373 |
+
if seed is not None:
|
| 374 |
+
torch.manual_seed(seed)
|
| 375 |
+
|
| 376 |
+
device = text_emb.device
|
| 377 |
+
B = text_emb.shape[0]
|
| 378 |
+
cfg = model.cfg
|
| 379 |
+
|
| 380 |
+
num_steps = num_steps or cfg.num_timesteps
|
| 381 |
+
|
| 382 |
+
# Latent spatial size
|
| 383 |
+
H = W = cfg.image_size // (2 ** cfg.ae_num_blocks)
|
| 384 |
+
|
| 385 |
+
# Start from random noise
|
| 386 |
+
z = torch.randn(B, cfg.latent_dim, H, W, device=device)
|
| 387 |
+
|
| 388 |
+
# For classifier-free guidance, we need an unconditional embedding (zeros)
|
| 389 |
+
if cfg_scale != 1.0:
|
| 390 |
+
uncond_emb = torch.zeros_like(text_emb)
|
| 391 |
+
|
| 392 |
+
# Time step resampling for faster inference (DDPM-style, evenly spaced)
|
| 393 |
+
step_indices = torch.linspace(0, cfg.num_timesteps - 1, num_steps, device=device, dtype=torch.long)
|
| 394 |
+
|
| 395 |
+
for i in range(num_steps - 1, -1, -1):
|
| 396 |
+
t = step_indices[i]
|
| 397 |
+
t_batch = t.expand(B)
|
| 398 |
+
|
| 399 |
+
# Predict noise
|
| 400 |
+
if cfg_scale != 1.0:
|
| 401 |
+
# Classifier-free guidance: combine conditional and unconditional predictions
|
| 402 |
+
z_in = torch.cat([z, z], dim=0)
|
| 403 |
+
t_in = torch.cat([t_batch, t_batch], dim=0)
|
| 404 |
+
text_in = torch.cat([text_emb, uncond_emb], dim=0)
|
| 405 |
+
noise_pred = model(z_in, text_in, t_in)
|
| 406 |
+
noise_cond, noise_uncond = noise_pred.chunk(2, dim=0)
|
| 407 |
+
noise_pred = noise_uncond + cfg_scale * (noise_cond - noise_uncond)
|
| 408 |
+
else:
|
| 409 |
+
noise_pred = model(z, text_emb, t_batch)
|
| 410 |
+
|
| 411 |
+
# DDPM update step
|
| 412 |
+
alpha = self.alphas[t]
|
| 413 |
+
alpha_cumprod = self.alphas_cumprod[t]
|
| 414 |
+
beta = self.betas[t]
|
| 415 |
+
|
| 416 |
+
# Compute predicted x0 (for logging purposes, not needed for step)
|
| 417 |
+
# x0_pred = (z - sqrt_one_minus_ac * noise_pred) / sqrt_ac
|
| 418 |
+
|
| 419 |
+
# Mean for posterior
|
| 420 |
+
coef1 = 1.0 / alpha.sqrt()
|
| 421 |
+
coef2 = beta / (1.0 - alpha_cumprod).sqrt()
|
| 422 |
+
z_mean = coef1 * (z - coef2 * noise_pred)
|
| 423 |
+
|
| 424 |
+
if i > 0:
|
| 425 |
+
noise = torch.randn_like(z)
|
| 426 |
+
z = z_mean + beta.sqrt() * noise
|
| 427 |
+
else:
|
| 428 |
+
z = z_mean
|
| 429 |
+
|
| 430 |
+
return z
|
| 431 |
+
|
| 432 |
+
|
| 433 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 434 |
+
# High-Level Inference Pipeline
|
| 435 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 436 |
+
|
| 437 |
+
class ShellDInference:
|
| 438 |
+
"""
|
| 439 |
+
High-level pipeline for ShellD text-to-image generation.
|
| 440 |
+
|
| 441 |
+
Usage:
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| 442 |
+
pipe = ShellDInference("./ShellD_model")
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| 443 |
+
img = pipe.generate("a cat sitting on a mat")
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| 444 |
+
img.save("cat.png")
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| 445 |
+
"""
|
| 446 |
+
|
| 447 |
+
def __init__(
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| 448 |
+
self,
|
| 449 |
+
model_dir: str,
|
| 450 |
+
device: Optional[str] = None,
|
| 451 |
+
text_encoder_path: Optional[str] = None,
|
| 452 |
+
):
|
| 453 |
+
"""
|
| 454 |
+
Args:
|
| 455 |
+
model_dir: Path to the model directory, or a Hugging Face repo ID
|
| 456 |
+
(e.g. "FlameF0X/ShellD"). If a repo ID is given, the
|
| 457 |
+
weights are automatically downloaded via huggingface_hub.
|
| 458 |
+
device: Device to run on ('cuda', 'cpu', or None for auto-detect).
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| 459 |
+
text_encoder_path: Optional override path for the text encoder model.
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| 460 |
+
Defaults to the path in config.json.
|
| 461 |
+
"""
|
| 462 |
+
self.device = torch.device(
|
| 463 |
+
device or ("cuda" if torch.cuda.is_available() else "cpu")
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| 464 |
+
)
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| 465 |
+
print(f"ShellD inference using device: {self.device}")
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| 466 |
+
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| 467 |
+
# Resolve model source: Hugging Face repo or local path
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| 468 |
+
local_path = Path(model_dir)
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| 469 |
+
if local_path.exists():
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| 470 |
+
# Local directory
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| 471 |
+
self.model_dir = local_path
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| 472 |
+
else:
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| 473 |
+
# Assume it's a Hugging Face repo ID β download via hub
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| 474 |
+
print(f"Downloading model from Hugging Face: {model_dir}")
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| 475 |
+
self.model_dir = Path(snapshot_download(repo_id=model_dir))
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| 476 |
+
print(f"Model cached at: {self.model_dir}")
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| 477 |
+
|
| 478 |
+
# 1. Load config
|
| 479 |
+
config_path = self.model_dir / "config.json"
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| 480 |
+
if not config_path.exists():
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| 481 |
+
raise FileNotFoundError(f"config.json not found at {config_path}")
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| 482 |
+
self.cfg = ShellDConfig.from_json(str(config_path))
|
| 483 |
+
|
| 484 |
+
# 2. Build model
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| 485 |
+
self.model = ShellDModel(self.cfg).to(self.device)
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| 486 |
+
self.model.eval()
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| 487 |
+
|
| 488 |
+
# 3. Load weights
|
| 489 |
+
weights_path = self.model_dir / "model.safetensors"
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| 490 |
+
if not weights_path.exists():
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| 491 |
+
raise FileNotFoundError(f"model.safetensors not found at {weights_path}")
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| 492 |
+
self._load_weights(str(weights_path))
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| 493 |
+
|
| 494 |
+
# 4. Load text encoder
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+
encoder_path = text_encoder_path or self.cfg.text_encoder_name
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| 496 |
+
print(f"Loading text encoder from: {encoder_path}")
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| 497 |
+
self.model.text_encoder = SentenceTransformer(encoder_path)
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| 498 |
+
|
| 499 |
+
# 5. Diffusion schedule
|
| 500 |
+
self.diffusion = DiffusionSchedule(self.cfg, self.device)
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| 501 |
+
|
| 502 |
+
# Print parameter count
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| 503 |
+
total = sum(p.numel() for p in self.model.parameters())
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| 504 |
+
trainable = sum(p.numel() for p in self.model.parameters() if p.requires_grad)
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| 505 |
+
print(f"Model loaded: {total:,} total params ({trainable:,} trainable)")
|
| 506 |
+
|
| 507 |
+
def _load_weights(self, weights_path: str):
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| 508 |
+
"""Load state dict, mapping prefixes to the correct submodules."""
|
| 509 |
+
sd = load_file(weights_path)
|
| 510 |
+
|
| 511 |
+
vae_sd = {k.replace("vae.", ""): v for k, v in sd.items() if k.startswith("vae.")}
|
| 512 |
+
dit_sd = {k.replace("dit.", ""): v for k, v in sd.items() if k.startswith("dit.")}
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| 513 |
+
txt_sd = {k.replace("text_encoder.", ""): v for k, v in sd.items() if k.startswith("text_encoder.")}
|
| 514 |
+
|
| 515 |
+
self.model.vae.load_state_dict(vae_sd)
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| 516 |
+
self.model.dit.load_state_dict(dit_sd)
|
| 517 |
+
|
| 518 |
+
if txt_sd and self.model.text_encoder is not None:
|
| 519 |
+
self.model.text_encoder.load_state_dict(txt_sd)
|
| 520 |
+
print("Text encoder weights loaded from safetensors.")
|
| 521 |
+
else:
|
| 522 |
+
print("Text encoder loaded from SentenceTransformer cache (weights not in safetensors).")
|
| 523 |
+
|
| 524 |
+
@torch.no_grad()
|
| 525 |
+
def generate(
|
| 526 |
+
self,
|
| 527 |
+
prompt: str,
|
| 528 |
+
num_steps: int = 250,
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| 529 |
+
cfg_scale: float = 3.0,
|
| 530 |
+
seed: Optional[int] = None,
|
| 531 |
+
output_size: Optional[int] = None,
|
| 532 |
+
) -> Image.Image:
|
| 533 |
+
"""
|
| 534 |
+
Generate an image from a text prompt.
|
| 535 |
+
|
| 536 |
+
Args:
|
| 537 |
+
prompt: Text description of the desired image.
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| 538 |
+
num_steps: Number of denoising steps (fewer = faster, lower quality).
|
| 539 |
+
Recommended: 250-1000.
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| 540 |
+
cfg_scale: Classifier-free guidance scale. Higher = more prompt adherence.
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| 541 |
+
1.0 = no guidance. Typical range: 2.0-5.0.
|
| 542 |
+
seed: Random seed for reproducibility.
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| 543 |
+
output_size: If set, the output image is resized to (output_size, output_size).
|
| 544 |
+
|
| 545 |
+
Returns:
|
| 546 |
+
A PIL Image.
|
| 547 |
+
"""
|
| 548 |
+
self.model.eval()
|
| 549 |
+
|
| 550 |
+
# Encode prompt
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| 551 |
+
text_emb = self.model.encode_text([prompt], self.device) # [1, 1, 384]
|
| 552 |
+
|
| 553 |
+
# Sample latent
|
| 554 |
+
z = self.diffusion.sample(
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| 555 |
+
self.model,
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| 556 |
+
text_emb,
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| 557 |
+
num_steps=num_steps,
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| 558 |
+
cfg_scale=cfg_scale,
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| 559 |
+
seed=seed,
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| 560 |
+
)
|
| 561 |
+
|
| 562 |
+
# Decode latent to image
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| 563 |
+
img_tensor = self.model.vae.decode(z) # [1, 3, 256, 256], values in [0, 1]
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| 564 |
+
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| 565 |
+
# Convert to PIL
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| 566 |
+
img_np = img_tensor[0].permute(1, 2, 0).cpu().numpy() # [256, 256, 3]
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| 567 |
+
img_np = (img_np * 255).clip(0, 255).astype(np.uint8)
|
| 568 |
+
img = Image.fromarray(img_np)
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| 569 |
+
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| 570 |
+
if output_size is not None:
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| 571 |
+
img = img.resize((output_size, output_size), Image.Resampling.BICUBIC)
|
| 572 |
+
|
| 573 |
+
return img
|
| 574 |
+
|
| 575 |
+
@torch.no_grad()
|
| 576 |
+
def generate_batch(
|
| 577 |
+
self,
|
| 578 |
+
prompts: List[str],
|
| 579 |
+
num_steps: int = 250,
|
| 580 |
+
cfg_scale: float = 3.0,
|
| 581 |
+
seed: Optional[int] = None,
|
| 582 |
+
) -> List[Image.Image]:
|
| 583 |
+
"""
|
| 584 |
+
Generate images for multiple prompts efficiently (batched).
|
| 585 |
+
|
| 586 |
+
Args:
|
| 587 |
+
prompts: List of text prompts.
|
| 588 |
+
num_steps: Number of denoising steps.
|
| 589 |
+
cfg_scale: Classifier-free guidance scale.
|
| 590 |
+
seed: Random seed (applied per-prompt).
|
| 591 |
+
|
| 592 |
+
Returns:
|
| 593 |
+
List of PIL Images.
|
| 594 |
+
"""
|
| 595 |
+
self.model.eval()
|
| 596 |
+
B = len(prompts)
|
| 597 |
+
|
| 598 |
+
# Encode all prompts
|
| 599 |
+
text_emb = self.model.encode_text(prompts, self.device) # [B, 1, 384]
|
| 600 |
+
|
| 601 |
+
# Sample latents
|
| 602 |
+
z = self.diffusion.sample(
|
| 603 |
+
self.model,
|
| 604 |
+
text_emb,
|
| 605 |
+
num_steps=num_steps,
|
| 606 |
+
cfg_scale=cfg_scale,
|
| 607 |
+
seed=seed,
|
| 608 |
+
)
|
| 609 |
+
|
| 610 |
+
# Decode
|
| 611 |
+
img_tensor = self.model.vae.decode(z) # [B, 3, 256, 256]
|
| 612 |
+
|
| 613 |
+
images = []
|
| 614 |
+
for i in range(B):
|
| 615 |
+
img_np = img_tensor[i].permute(1, 2, 0).cpu().numpy()
|
| 616 |
+
img_np = (img_np * 255).clip(0, 255).astype(np.uint8)
|
| 617 |
+
images.append(Image.fromarray(img_np))
|
| 618 |
+
|
| 619 |
+
return images
|
| 620 |
+
|
| 621 |
+
|
| 622 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 623 |
+
# Command-Line Interface
|
| 624 |
+
# βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
|
| 625 |
+
|
| 626 |
+
def main():
|
| 627 |
+
import argparse
|
| 628 |
+
|
| 629 |
+
parser = argparse.ArgumentParser(description="ShellD - Text-to-Image Generation")
|
| 630 |
+
parser.add_argument("--model_dir", type=str, default="FlameF0X/ShellD",
|
| 631 |
+
help="Path to model directory or Hugging Face repo ID (default: FlameF0X/ShellD)")
|
| 632 |
+
parser.add_argument("--text_encoder", type=str, default=None,
|
| 633 |
+
help="Override path for the text encoder model")
|
| 634 |
+
parser.add_argument("--prompt", type=str, required=True,
|
| 635 |
+
help="Text prompt for image generation")
|
| 636 |
+
parser.add_argument("--output", type=str, default="output.png",
|
| 637 |
+
help="Output image path")
|
| 638 |
+
parser.add_argument("--steps", type=int, default=250,
|
| 639 |
+
help="Number of denoising steps (default: 250)")
|
| 640 |
+
parser.add_argument("--cfg", type=float, default=3.0,
|
| 641 |
+
help="Classifier-free guidance scale (default: 3.0)")
|
| 642 |
+
parser.add_argument("--seed", type=int, default=None,
|
| 643 |
+
help="Random seed for reproducibility")
|
| 644 |
+
parser.add_argument("--device", type=str, default=None,
|
| 645 |
+
help="Device: 'cuda' or 'cpu'")
|
| 646 |
+
parser.add_argument("--size", type=int, default=None,
|
| 647 |
+
help="Output image size (square, resized)")
|
| 648 |
+
|
| 649 |
+
args = parser.parse_args()
|
| 650 |
+
|
| 651 |
+
pipe = ShellDInference(
|
| 652 |
+
model_dir=args.model_dir,
|
| 653 |
+
device=args.device,
|
| 654 |
+
text_encoder_path=args.text_encoder,
|
| 655 |
+
)
|
| 656 |
+
|
| 657 |
+
img = pipe.generate(
|
| 658 |
+
prompt=args.prompt,
|
| 659 |
+
num_steps=args.steps,
|
| 660 |
+
cfg_scale=args.cfg,
|
| 661 |
+
seed=args.seed,
|
| 662 |
+
output_size=args.size,
|
| 663 |
+
)
|
| 664 |
+
|
| 665 |
+
img.save(args.output)
|
| 666 |
+
print(f"Image saved to {args.output}")
|
| 667 |
+
|
| 668 |
+
|
| 669 |
+
if __name__ == "__main__":
|
| 670 |
+
main()
|