update readme

* bugfix

README.md

@@ -381,6 +381,8 @@ https://github.com/Artiprocher/DiffSynth-Studio/assets/35051019/59fb2f7b-8de0-44
 
 ## Update History
 
+- **September 22, 2025**: We have supported Direct Preference Optimization (DPO) training for Qwen-Image. Please refer to the [example code](examples/qwen_image/model_training/lora/Qwen-Image-DPO.sh) for the training script.
+
 - **September 9, 2025**: Our training framework now supports multiple training modes and has been adapted for Qwen-Image. In addition to the standard SFT training mode, Direct Distill is now also supported; please refer to [our example code](./examples/qwen_image/model_training/lora/Qwen-Image-Distill-LoRA.sh). This feature is experimental, and we will continue to improve it to support comprehensive model training capabilities.
 
 - **August 28, 2025** We support Wan2.2-S2V, an audio-driven cinematic video generation model open-sourced by Alibaba. See [./examples/wanvideo/](./examples/wanvideo/).

README_zh.md

@@ -397,6 +397,8 @@ https://github.com/Artiprocher/DiffSynth-Studio/assets/35051019/59fb2f7b-8de0-44
 
 ## 更新历史
 
+- **2025年9月22日** 我们支持了 Qwen-Image 的直接偏好对齐 (DPO) 训练，训练脚本请参考[示例代码](examples/qwen_image/model_training/lora/Qwen-Image-DPO.sh)。
+
 - **2025年9月9日** 我们的训练框架支持了多种训练模式，目前已适配 Qwen-Image，除标准 SFT 训练模式外，已支持 Direct Distill，请参考[我们的示例代码](./examples/qwen_image/model_training/lora/Qwen-Image-Distill-LoRA.sh)。这项功能是实验性的，我们将会继续完善已支持更全面的模型训练功能。
 
 - **2025年8月28日** 我们支持了Wan2.2-S2V，一个音频驱动的电影级视频生成模型。请参见[./examples/wanvideo/](./examples/wanvideo/)。

diffsynth/extensions/FastBlend/patch_match.py

@@ -2,7 +2,8 @@ from .cupy_kernels import remapping_kernel, patch_error_kernel, pairwise_patch_e
 import numpy as np
 import cupy as cp
 import cv2
-
+import torch
+import torch.nn.functional as F
 
 class PatchMatcher:
     def __init__(
@@ -233,13 +234,11 @@ class PyramidPatchMatcher:
 
     def resample_image(self, images, level):
         height, width = self.pyramid_heights[level], self.pyramid_widths[level]
-        images = images.get()
+        images_torch = torch.as_tensor(images, device='cuda', dtype=torch.float32)
-        images_resample = []
+        images_torch = images_torch.permute(0, 3, 1, 2)
-        for image in images:
+        images_resample = F.interpolate(images_torch, size=(height, width), mode='area', align_corners=None)
-            image_resample = cv2.resize(image, (width, height), interpolation=cv2.INTER_AREA)
+        images_resample = images_resample.permute(0, 2, 3, 1).contiguous()
-            images_resample.append(image_resample)
+        return cp.asarray(images_resample)
-        images_resample = cp.array(np.stack(images_resample), dtype=cp.float32)
-        return images_resample
 
     def initialize_nnf(self, batch_size):
         if self.initialize == "random":
@@ -262,14 +261,16 @@ class PyramidPatchMatcher:
     def update_nnf(self, nnf, level):
         # upscale
         nnf = nnf.repeat(2, axis=1).repeat(2, axis=2) * 2
-        nnf[:,[i for i in range(nnf.shape[0]) if i&1],:,0] += 1
+        nnf[:, 1::2, :, 0] += 1
-        nnf[:,:,[i for i in range(nnf.shape[0]) if i&1],1] += 1
+        nnf[:, :, 1::2, 1] += 1
         # check if scale is 2
         height, width = self.pyramid_heights[level], self.pyramid_widths[level]
         if height != nnf.shape[0] * 2 or width != nnf.shape[1] * 2:
-            nnf = nnf.get().astype(np.float32)
+            nnf_torch = torch.as_tensor(nnf, device='cuda', dtype=torch.float32)
-            nnf = [cv2.resize(n, (width, height), interpolation=cv2.INTER_LINEAR) for n in nnf]
+            nnf_torch = nnf_torch.permute(0, 3, 1, 2)
-            nnf = cp.array(np.stack(nnf), dtype=cp.int32)
+            nnf_resized = F.interpolate(nnf_torch, size=(height, width), mode='bilinear', align_corners=False)
+            nnf_resized = nnf_resized.permute(0, 2, 3, 1)
+            nnf = cp.asarray(nnf_resized).astype(cp.int32)
             nnf = self.patch_matchers[level].clamp_bound(nnf)
         return nnf
 

diffsynth/pipelines/qwen_image.py

@@ -140,8 +140,9 @@ class QwenImagePipeline(BasePipeline):
         timestep_id = torch.randint(0, self.scheduler.num_train_timesteps, (1,))
         timestep = self.scheduler.timesteps[timestep_id].to(dtype=self.torch_dtype, device=self.device)
         
-        inputs["latents"] = self.scheduler.add_noise(inputs["input_latents"], inputs["noise"], timestep)
+        noise = torch.randn_like(inputs["input_latents"])
-        training_target = self.scheduler.training_target(inputs["input_latents"], inputs["noise"], timestep)
+        inputs["latents"] = self.scheduler.add_noise(inputs["input_latents"], noise, timestep)
+        training_target = self.scheduler.training_target(inputs["input_latents"], noise, timestep)
         
         noise_pred = self.model_fn(**inputs, timestep=timestep)
         
@@ -371,6 +372,7 @@ class QwenImagePipeline(BasePipeline):
         rand_device: str = "cpu",
         # Steps
         num_inference_steps: int = 30,
+        exponential_shift_mu: float = None,
         # Blockwise ControlNet
         blockwise_controlnet_inputs: list[ControlNetInput] = None,
         # EliGen
@@ -393,7 +395,7 @@ class QwenImagePipeline(BasePipeline):
         progress_bar_cmd = tqdm,
     ):
         # Scheduler
-        self.scheduler.set_timesteps(num_inference_steps, denoising_strength=denoising_strength, dynamic_shift_len=(height // 16) * (width // 16))
+        self.scheduler.set_timesteps(num_inference_steps, denoising_strength=denoising_strength, dynamic_shift_len=(height // 16) * (width // 16), exponential_shift_mu=exponential_shift_mu)
         
         # Parameters
         inputs_posi = {
@@ -523,7 +525,7 @@ class QwenImageUnit_PromptEmbedder(PipelineUnit):
         return split_result
 
     def process(self, pipe: QwenImagePipeline, prompt, edit_image=None) -> dict:
-        if pipe.text_encoder is not None:
+        if pipe.text_encoder is not None and prompt is not None:
             prompt = [prompt]
             # If edit_image is None, use the default template for Qwen-Image, otherwise use the template for Qwen-Image-Edit
             if edit_image is None:

diffsynth/schedulers/flow_match.py

@@ -31,7 +31,7 @@ class FlowMatchScheduler():
         self.set_timesteps(num_inference_steps)
 
 
-    def set_timesteps(self, num_inference_steps=100, denoising_strength=1.0, training=False, shift=None, dynamic_shift_len=None):
+    def set_timesteps(self, num_inference_steps=100, denoising_strength=1.0, training=False, shift=None, dynamic_shift_len=None, exponential_shift_mu=None):
         if shift is not None:
             self.shift = shift
         sigma_start = self.sigma_min + (self.sigma_max - self.sigma_min) * denoising_strength
@@ -42,7 +42,12 @@ class FlowMatchScheduler():
         if self.inverse_timesteps:
             self.sigmas = torch.flip(self.sigmas, dims=[0])
         if self.exponential_shift:
-            mu = self.calculate_shift(dynamic_shift_len) if dynamic_shift_len is not None else self.exponential_shift_mu
+            if exponential_shift_mu is not None:
+                mu = exponential_shift_mu
+            elif dynamic_shift_len is not None:
+                mu = self.calculate_shift(dynamic_shift_len)
+            else:
+                mu = self.exponential_shift_mu
             self.sigmas = math.exp(mu) / (math.exp(mu) + (1 / self.sigmas - 1))
         else:
             self.sigmas = self.shift * self.sigmas / (1 + (self.shift - 1) * self.sigmas)

diffsynth/trainers/utils.py

@@ -396,6 +396,15 @@ class DiffusionTrainingModule(torch.nn.Module):
                     param.data = param.to(upcast_dtype)
         return model
 
+    def disable_all_lora_layers(self, model):
+        for name, module in model.named_modules():
+            if hasattr(module, 'enable_adapters'):
+                module.enable_adapters(False)
+
+    def enable_all_lora_layers(self, model):
+        for name, module in model.named_modules():
+            if hasattr(module, 'enable_adapters'):
+                module.enable_adapters(True)
 
     def mapping_lora_state_dict(self, state_dict):
         new_state_dict = {}
@@ -421,10 +430,12 @@ class DiffusionTrainingModule(torch.nn.Module):
         return state_dict
     
     
-    def transfer_data_to_device(self, data, device):
+    def transfer_data_to_device(self, data, device, torch_float_dtype=None):
         for key in data:
             if isinstance(data[key], torch.Tensor):
                 data[key] = data[key].to(device)
+                if torch_float_dtype is not None and data[key].dtype in [torch.float, torch.float16, torch.bfloat16]:
+                    data[key] = data[key].to(torch_float_dtype)
         return data
     
     
@@ -552,9 +563,9 @@ def launch_training_task(
             with accelerator.accumulate(model):
                 optimizer.zero_grad()
                 if dataset.load_from_cache:
-                    loss = model({}, inputs=data)
+                    loss = model({}, inputs=data, accelerator=accelerator)
                 else:
-                    loss = model(data)
+                    loss = model(data, accelerator=accelerator)
                 accelerator.backward(loss)
                 optimizer.step()
                 model_logger.on_step_end(accelerator, model, save_steps)
@@ -688,4 +699,5 @@ def qwen_image_parser():
     parser.add_argument("--processor_path", type=str, default=None, help="Path to the processor. If provided, the processor will be used for image editing.")
     parser.add_argument("--enable_fp8_training", default=False, action="store_true", help="Whether to enable FP8 training. Only available for LoRA training on a single GPU.")
     parser.add_argument("--task", type=str, default="sft", required=False, help="Task type.")
+    parser.add_argument("--beta_dpo", type=float, default=1000, help="hyperparameter beta for DPO loss, only used when task is dpo.")
     return parser

diffsynth/utils/__init__.py

@@ -153,6 +153,19 @@ class BasePipeline(torch.nn.Module):
         latents_next = scheduler.step(noise_pred, timestep, latents)
         return latents_next
 
+    def sample_timestep(self):
+        timestep_id = torch.randint(0, self.scheduler.num_train_timesteps, (1,))
+        timestep = self.scheduler.timesteps[timestep_id].to(dtype=self.torch_dtype, device=self.device)
+        return timestep
+
+    def training_loss_minimum(self, noise, timestep, **inputs):
+        inputs["latents"] = self.scheduler.add_noise(inputs["input_latents"], noise, timestep)
+        training_target = self.scheduler.training_target(inputs["input_latents"], noise, timestep)
+        noise_pred = self.model_fn(**inputs, timestep=timestep)
+        loss = torch.nn.functional.mse_loss(noise_pred.float(), training_target.float())
+        loss = loss * self.scheduler.training_weight(timestep)
+        return loss
+
 
 
 @dataclass

examples/flux/model_training/train.py

@@ -75,7 +75,7 @@ class FluxTrainingModule(DiffusionTrainingModule):
         return {**inputs_shared, **inputs_posi}
     
     
-    def forward(self, data, inputs=None):
+    def forward(self, data, inputs=None, **kwargs):
         if inputs is None: inputs = self.forward_preprocess(data)
         models = {name: getattr(self.pipe, name) for name in self.pipe.in_iteration_models}
         loss = self.pipe.training_loss(**models, **inputs)

examples/qwen_image/model_inference/Qwen-Image-Distill-DMD2.py

@@ -0,0 +1,24 @@
+from diffsynth.pipelines.qwen_image import QwenImagePipeline, ModelConfig, load_state_dict
+from modelscope import snapshot_download
+import torch, math
+
+
+pipe = QwenImagePipeline.from_pretrained(
+    torch_dtype=torch.bfloat16,
+    device="cuda",
+    model_configs=[
+        ModelConfig(model_id="Qwen/Qwen-Image", origin_file_pattern="transformer/diffusion_pytorch_model*.safetensors"),
+        ModelConfig(model_id="Qwen/Qwen-Image", origin_file_pattern="text_encoder/model*.safetensors"),
+        ModelConfig(model_id="Qwen/Qwen-Image", origin_file_pattern="vae/diffusion_pytorch_model.safetensors"),
+    ],
+    tokenizer_config=ModelConfig(model_id="Qwen/Qwen-Image", origin_file_pattern="tokenizer/"),
+)
+
+snapshot_download("MusePublic/Qwen-Image-Distill", allow_file_pattern="qwen_image_distill_3step.safetensors", cache_dir="models")
+lora_state_dict = load_state_dict("models/MusePublic/Qwen-Image-Distill/qwen_image_distill_3step.safetensors")
+lora_state_dict = {i.replace("base_model.model.", ""): j for i, j in lora_state_dict.items()}
+pipe.load_lora(pipe.dit, state_dict=lora_state_dict)
+
+prompt = "精致肖像，水下少女，蓝裙飘逸，发丝轻扬，光影透澈，气泡环绕，面容恬静，细节精致，梦幻唯美。"
+image = pipe(prompt, seed=0, num_inference_steps=3, cfg_scale=1, exponential_shift_mu=math.log(2.5))
+image.save("image.jpg")

examples/qwen_image/model_training/lora/Qwen-Image-DPO.sh

@@ -0,0 +1,25 @@
+# dataset format: 
+# {
+#   "image": "path/to/win_image.png", # win image
+#   "lose_image": "path/to/lose_image.png", # lose image
+#   "prompt": "a photo of ...",
+# }
+accelerate launch examples/qwen_image/model_training/train.py \
+  --dataset_base_path data/example_image_dataset \
+  --dataset_metadata_path data/example_image_dataset/dpo.jsonl \
+  --data_file_keys "image,lose_image" \
+  --max_pixels 1048576 \
+  --dataset_repeat 400 \
+  --model_id_with_origin_paths "Qwen/Qwen-Image:transformer/diffusion_pytorch_model*.safetensors,Qwen/Qwen-Image:text_encoder/model*.safetensors,Qwen/Qwen-Image:vae/diffusion_pytorch_model.safetensors" \
+  --learning_rate 1e-4 \
+  --num_epochs 5 \
+  --remove_prefix_in_ckpt "pipe.dit." \
+  --output_path "./models/train/Qwen-Image_DPO_lora" \
+  --lora_base_model "dit" \
+  --lora_target_modules "to_q,to_k,to_v,add_q_proj,add_k_proj,add_v_proj,to_out.0,to_add_out,img_mlp.net.2,img_mod.1,txt_mlp.net.2,txt_mod.1" \
+  --lora_rank 32 \
+  --use_gradient_checkpointing \
+  --dataset_num_workers 8 \
+  --task dpo \
+  --beta_dpo 2500 \
+  --find_unused_parameters

examples/qwen_image/model_training/train.py

@@ -1,5 +1,4 @@
-import torch, os, json
+import torch, os
-from diffsynth import load_state_dict
 from diffsynth.pipelines.qwen_image import QwenImagePipeline, ModelConfig
 from diffsynth.pipelines.flux_image_new import ControlNetInput
 from diffsynth.trainers.utils import DiffusionTrainingModule, ModelLogger, qwen_image_parser, launch_training_task, launch_data_process_task
@@ -7,7 +6,6 @@ from diffsynth.trainers.unified_dataset import UnifiedDataset
 os.environ["TOKENIZERS_PARALLELISM"] = "false"
 
 
-
 class QwenImageTrainingModule(DiffusionTrainingModule):
     def __init__(
         self,
@@ -20,6 +18,7 @@ class QwenImageTrainingModule(DiffusionTrainingModule):
         extra_inputs=None,
         enable_fp8_training=False,
         task="sft",
+        beta_dpo=1000.,
     ):
         super().__init__()
         # Load models
@@ -40,7 +39,8 @@ class QwenImageTrainingModule(DiffusionTrainingModule):
         self.use_gradient_checkpointing_offload = use_gradient_checkpointing_offload
         self.extra_inputs = extra_inputs.split(",") if extra_inputs is not None else []
         self.task = task
-
+        self.lora_base_model = lora_base_model
+        self.beta_dpo = beta_dpo
 
     def forward_preprocess(self, data):
         # CFG-sensitive parameters
@@ -82,11 +82,48 @@ class QwenImageTrainingModule(DiffusionTrainingModule):
             inputs_shared, inputs_posi, inputs_nega = self.pipe.unit_runner(unit, self.pipe, inputs_shared, inputs_posi, inputs_nega)
         return {**inputs_shared, **inputs_posi}
 
+    def forward_dpo(self, data, accelerator=None):
+        # Loss DPO: -logσ(−β(diff_policy − diff_ref))
+        # Prepare inputs
+        win_data = {key: data[key] for key in ["prompt", "image"]}
+        lose_data = {"prompt": None, "image": data["lose_image"]}
+        inputs_win = self.forward_preprocess(win_data)
+        inputs_lose = self.forward_preprocess(lose_data)
+        inputs_lose.update({key: inputs_win[key] for key in ["prompt", "prompt_emb", "prompt_emb_mask"]})
+        inputs_win.pop('noise')
+        inputs_lose.pop('noise')
+        models = {name: getattr(self.pipe, name) for name in self.pipe.in_iteration_models}
+        # sample timestep and noise
+        timestep = self.pipe.sample_timestep()
+        noise = torch.rand_like(inputs_win["latents"])
+        # compute diff_policy = loss_win - loss_lose
+        loss_win = self.pipe.training_loss_minimum(noise, timestep, **models, **inputs_win)
+        loss_lose = self.pipe.training_loss_minimum(noise, timestep, **models, **inputs_lose)
+        diff_policy = loss_win - loss_lose
+        # compute diff_ref
+        if self.lora_base_model is not None:
+            self.disable_all_lora_layers(accelerator.unwrap_model(self).pipe.dit)
+            # load the original model weights
+            with torch.no_grad():
+                loss_win_ref = self.pipe.training_loss_minimum(noise, timestep, **models, **inputs_win)
+                loss_lose_ref = self.pipe.training_loss_minimum(noise, timestep, **models, **inputs_lose)
+                diff_ref = loss_win_ref - loss_lose_ref
+            self.enable_all_lora_layers(accelerator.unwrap_model(self).pipe.dit)
+        else:
+            # TODO: may support full model training
+            raise NotImplementedError("DPO with full model training is not supported yet.")
+        # compute loss
+        loss = -1. * torch.nn.functional.logsigmoid(self.beta_dpo * (diff_ref - diff_policy)).mean()
+        return loss
 
-    def forward(self, data, inputs=None, return_inputs=False):
+    def forward(self, data, inputs=None, return_inputs=False, accelerator=None, **kwargs):
+        if self.task == "dpo":
+            return self.forward_dpo(data, accelerator=accelerator)
         # Inputs
-        if inputs is None: inputs = self.forward_preprocess(data)
+        if inputs is None:
-        else: inputs = self.transfer_data_to_device(inputs, self.pipe.device)
+            inputs = self.forward_preprocess(data)
+        else:
+            inputs = self.transfer_data_to_device(inputs, self.pipe.device, self.pipe.torch_dtype)
         if return_inputs: return inputs
         
         # Loss
@@ -135,11 +172,13 @@ if __name__ == "__main__":
         extra_inputs=args.extra_inputs,
         enable_fp8_training=args.enable_fp8_training,
         task=args.task,
+        beta_dpo=args.beta_dpo,
     )
     model_logger = ModelLogger(args.output_path, remove_prefix_in_ckpt=args.remove_prefix_in_ckpt)
     launcher_map = {
         "sft": launch_training_task,
         "data_process": launch_data_process_task,
         "direct_distill": launch_training_task,
+        "dpo": launch_training_task,
     }
     launcher_map[args.task](dataset, model, model_logger, args=args)

examples/qwen_image/model_training/validate_lora/Qwen-Image-DPO.py

@@ -0,0 +1,19 @@
+from diffsynth.pipelines.qwen_image import QwenImagePipeline, ModelConfig
+import torch
+
+
+pipe = QwenImagePipeline.from_pretrained(
+    torch_dtype=torch.bfloat16,
+    device="cuda",
+    model_configs=[
+        ModelConfig(model_id="Qwen/Qwen-Image", origin_file_pattern="transformer/diffusion_pytorch_model*.safetensors"),
+        ModelConfig(model_id="Qwen/Qwen-Image", origin_file_pattern="text_encoder/model*.safetensors"),
+        ModelConfig(model_id="Qwen/Qwen-Image", origin_file_pattern="vae/diffusion_pytorch_model.safetensors"),
+    ],
+    tokenizer_config=ModelConfig(model_id="Qwen/Qwen-Image", origin_file_pattern="tokenizer/"),
+)
+pipe.load_lora(pipe.dit, "models/train/Qwen-Image_DPO_lora/epoch-4.safetensors")
+prompt = "黑板上写着“群起效尤,心灵手巧”，字的颜色分别是 “群”: 橙色、“起”: 黑色、“效”: 蓝色、“尤”: 绿色、“心”: 紫色、“灵”: 粉色、“手”: 红色、“巧”: 白色"
+for seed in range(0, 5):
+    image = pipe(prompt, seed=seed)
+    image.save(f"image_dpo_{seed}.jpg")

examples/wanvideo/model_training/train.py

@@ -82,7 +82,7 @@ class WanTrainingModule(DiffusionTrainingModule):
         return {**inputs_shared, **inputs_posi}
     
     
-    def forward(self, data, inputs=None):
+    def forward(self, data, inputs=None, **kwargs):
         if inputs is None: inputs = self.forward_preprocess(data)
         models = {name: getattr(self.pipe, name) for name in self.pipe.in_iteration_models}
         loss = self.pipe.training_loss(**models, **inputs)