Added Reward Backpropogation Support

docs/source/alignprop_trainer.mdx

@@ -0,0 +1,91 @@
+# Aligning Text-to-Image Diffusion Models with Reward Backpropagation
+
+## The why
+
+If your reward function is differentiable, directly backpropagating gradients from the reward models to the diffusion model is significantly more sample and compute efficient (25x) than doing policy gradient algorithm like DDPO.
+AlignProp does full backpropagation through time, which allows updating the earlier steps of denoising via reward backpropagation.
+
+<div style="text-align: center"><img src="https://align-prop.github.io/reward_tuning.png"/></div>
+
+
+## Getting started with `examples/scripts/alignprop.py`
+
+The `alignprop.py` script is a working example of using the `AlignProp` trainer to finetune a Stable Diffusion model. This example explicitly configures a small subset of the overall parameters associated with the config object (`AlignPropConfig`).
+
+**Note:** one A100 GPU is recommended to get this running. For lower memory setting, consider setting truncated_backprop_rand to False. With default settings this will do truncated backpropagation with K=1.
+
+Almost every configuration parameter has a default. There is only one commandline flag argument that is required of the user to get things up and running. The user is expected to have a [huggingface user access token](https://huggingface.co/docs/hub/security-tokens) that will be used to upload the model post finetuning to HuggingFace hub. The following bash command is to be entered to get things running
+
+```batch
+python alignprop.py --hf_user_access_token <token>
+```
+
+To obtain the documentation of `stable_diffusion_tuning.py`, please run `python stable_diffusion_tuning.py --help`
+
+The following are things to keep in mind (The code checks this for you as well) in general while configuring the trainer (beyond the use case of using the example script)
+
+- The configurable randomized truncation range (`--alignprop_config.truncated_rand_backprop_minmax=(0,50)`) the first number should be equal and greater to 0, while the second number should equal or less to the number of diffusion timesteps (sample_num_steps)
+- The configurable truncation backprop absolute step (`--alignprop_config.truncated_backprop_timestep=49`) the number should be less than the number of diffusion timesteps (sample_num_steps), it only matters when truncated_backprop_rand is set to False
+
+## Setting up the image logging hook function
+
+Expect the function to be given a dictionary with keys
+```python
+['image', 'prompt', 'prompt_metadata', 'rewards']
+
+```
+and `image`, `prompt`, `prompt_metadata`, `rewards`are batched.
+You are free to log however you want the use of `wandb` or `tensorboard` is recommended.
+
+### Key terms
+
+- `rewards` : The rewards/score is a numerical associated with the generated image and is key to steering the RL process
+- `prompt` : The prompt is the text that is used to generate the image
+- `prompt_metadata` : The prompt metadata is the metadata associated with the prompt. A situation where this will not be empty is when the reward model comprises of a [`FLAVA`](https://huggingface.co/docs/transformers/model_doc/flava) setup where questions and ground answers (linked to the generated image) are expected with the generated image (See here: https://github.com/kvablack/ddpo-pytorch/blob/main/ddpo_pytorch/rewards.py#L45)
+- `image` : The image generated by the Stable Diffusion model
+
+Example code for logging sampled images with `wandb` is given below.
+
+```python
+# for logging these images to wandb
+
+def image_outputs_hook(image_data, global_step, accelerate_logger):
+    # For the sake of this example, we only care about the last batch
+    # hence we extract the last element of the list
+    result = {}
+    images, prompts, rewards = [image_data['images'],image_data['prompts'],image_data['rewards']]
+    for i, image in enumerate(images):
+        pil = Image.fromarray(
+            (image.cpu().numpy().transpose(1, 2, 0) * 255).astype(np.uint8)
+        )
+        pil = pil.resize((256, 256))
+        result[f"{prompts[i]:.25} | {rewards[i]:.2f}"] = [pil]
+    accelerate_logger.log_images(
+        result,
+        step=global_step,
+    )
+
+```
+
+### Using the finetuned model
+
+Assuming you've done with all the epochs and have pushed up your model to the hub, you can use the finetuned model as follows
+
+```python
+from diffusers import StableDiffusionPipeline
+pipeline = StableDiffusionPipeline.from_pretrained("runwayml/stable-diffusion-v1-5")
+pipeline.to("cuda")
+
+pipeline.load_lora_weights('mihirpd/alignprop-trl-aesthetics')
+
+prompts = ["squirrel", "crab", "starfish", "whale","sponge", "plankton"]
+results = pipeline(prompts)
+
+for prompt, image in zip(prompts,results.images):
+    image.save(f"dump/{prompt}.png")
+```
+
+## Credits
+
+This work is heavily influenced by the repo [here](https://github.com/mihirp1998/AlignProp/) and the associated paper [Aligning Text-to-Image Diffusion Models with Reward Backpropagation
+ by Mihir Prabhudesai, Anirudh Goyal, Deepak Pathak, Katerina Fragkiadaki](https://arxiv.org/abs/2310.03739).

examples/scripts/alignprop.py

@@ -0,0 +1,129 @@
+# Copyright 2023 metric-space, The HuggingFace Team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+python examples/scripts/alignprop.py \
+    --num_epochs=20 \
+    --train_gradient_accumulation_steps=4 \
+    --sample_num_steps=50 \
+    --train_batch_size=8 \
+    --tracker_project_name="stable_diffusion_training" \
+    --log_with="wandb"
+"""
+import os
+from dataclasses import dataclass, field
+import numpy as np
+import torch
+import torch.nn as nn
+from transformers import  HfArgumentParser
+from trl import AlignPropConfig, AlignPropTrainer, DefaultDDPOStableDiffusionPipeline
+from trl.models.auxiliary_modules import aesthetic_scorer
+
+
+@dataclass
+class ScriptArguments:
+    pretrained_model: str = field(
+        default="runwayml/stable-diffusion-v1-5", metadata={"help": "the pretrained model to use"}
+    )
+    pretrained_revision: str = field(default="main", metadata={"help": "the pretrained model revision to use"})
+    hf_hub_model_id: str = field(
+        default="alignprop-finetuned-stable-diffusion", metadata={"help": "HuggingFace repo to save model weights to"}
+    )
+    hf_hub_aesthetic_model_id: str = field(
+        default="trl-lib/ddpo-aesthetic-predictor",
+        metadata={"help": "HuggingFace model ID for aesthetic scorer model weights"},
+    )
+    hf_hub_aesthetic_model_filename: str = field(
+        default="aesthetic-model.pth",
+        metadata={"help": "HuggingFace model filename for aesthetic scorer model weights"},
+    )
+    use_lora: bool = field(default=True, metadata={"help": "Whether to use LoRA."})
+
+
+
+# list of example prompts to feed stable diffusion
+animals = [
+    "cat",
+    "dog",
+    "horse",
+    "monkey",
+    "rabbit",
+    "zebra",
+    "spider",
+    "bird",
+    "sheep",
+    "deer",
+    "cow",
+    "goat",
+    "lion",
+    "frog",
+    "chicken",
+    "duck",
+    "goose",
+    "bee",
+    "pig",
+    "turkey",
+    "fly",
+    "llama",
+    "camel",
+    "bat",
+    "gorilla",
+    "hedgehog",
+    "kangaroo",
+]
+
+
+def prompt_fn():
+    return np.random.choice(animals), {}
+
+
+
+def image_outputs_logger(image_pair_data, global_step, accelerate_logger):
+    # For the sake of this example, we will only log the last batch of images
+    # and associated data
+    result = {}
+    images, prompts, rewards = [image_pair_data['images'],image_pair_data['prompts'],image_pair_data['rewards']]
+    for i, image in enumerate(images[:4]):
+        prompt = prompts[i]
+        reward = rewards[i].item()
+        result[f"{prompt}"] = image.unsqueeze(0).float()
+    accelerate_logger.log_images(
+        result,
+        step=global_step,
+    )
+
+
+if __name__ == "__main__":
+    parser = HfArgumentParser((ScriptArguments, AlignPropConfig))
+    args, alignprop_config = parser.parse_args_into_dataclasses()
+    alignprop_config.project_kwargs = {
+        "logging_dir": "./logs",
+        "automatic_checkpoint_naming": True,
+        "total_limit": 5,
+        "project_dir": "./save",
+    }
+
+    pipeline = DefaultDDPOStableDiffusionPipeline(
+        args.pretrained_model, pretrained_model_revision=args.pretrained_revision, use_lora=args.use_lora
+    )
+    trainer = AlignPropTrainer(
+        alignprop_config,
+        aesthetic_scorer(args.hf_hub_aesthetic_model_id, args.hf_hub_aesthetic_model_filename),
+        prompt_fn,
+        pipeline,
+        image_samples_hook=image_outputs_logger,
+    )
+
+    trainer.train()
+
+    trainer.push_to_hub(args.hf_hub_model_id)

tests/test_alignprop_trainer.py

@@ -0,0 +1,110 @@
+# Copyright 2023 metric-space, The HuggingFace Team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import gc
+import unittest
+import torch
+
+from trl import is_diffusers_available, is_peft_available
+
+from .testing_utils import require_diffusers
+
+
+if is_diffusers_available() and is_peft_available():
+    from trl import AlignPropConfig, AlignPropTrainer, DefaultDDPOStableDiffusionPipeline
+
+
+def scorer_function(images, prompts, metadata):
+    return torch.randn(1) * 3.0, {}
+
+
+def prompt_function():
+    return ("cabbages", {})
+
+
+@require_diffusers
+class AlignPropTrainerTester(unittest.TestCase):
+    """
+    Test the AlignPropTrainer class.
+    """
+
+    def setUp(self):
+        self.alignprop_config = AlignPropConfig(
+            num_epochs=2,
+            train_gradient_accumulation_steps=1,
+            train_batch_size=2,
+            truncated_backprop_rand=False,
+            mixed_precision=None,
+            save_freq=1000000,
+        )
+        pretrained_model = "hf-internal-testing/tiny-stable-diffusion-torch"
+        pretrained_revision = "main"
+
+        pipeline = DefaultDDPOStableDiffusionPipeline(
+            pretrained_model, pretrained_model_revision=pretrained_revision, use_lora=False
+        )
+
+        self.trainer = AlignPropTrainer(self.alignprop_config, scorer_function, prompt_function, pipeline)
+
+        return super().setUp()
+
+    def tearDown(self) -> None:
+        gc.collect()
+
+    def test_generate_samples(self):
+        output_pairs = self.trainer._generate_samples(2, with_grad=True)
+        assert len(output_pairs.keys()) == 3
+        assert len(output_pairs['images']) == 2
+
+    def test_calculate_loss(self):
+        sample = self.trainer._generate_samples(2)
+
+        images = sample["images"]
+        prompts = sample["prompts"]
+
+        assert images.shape == (2, 3, 128, 128)
+        assert len(prompts) == 2
+
+        rewards = self.trainer.compute_rewards(
+            sample
+        )
+        loss = self.trainer.calculate_loss(rewards)        
+
+        assert torch.isfinite(loss.cpu())
+
+
+@require_diffusers
+class AlignPropTrainerWithLoRATester(AlignPropTrainerTester):
+    """
+    Test the AlignPropTrainer class.
+    """
+
+    def setUp(self):
+        self.alignprop_config = AlignPropConfig(
+            num_epochs=2,
+            train_gradient_accumulation_steps=1,
+            mixed_precision=None,
+            truncated_backprop_rand=False,
+            save_freq=1000000,
+        )
+
+        pretrained_model = "hf-internal-testing/tiny-stable-diffusion-torch"
+        pretrained_revision = "main"
+
+        pipeline = DefaultDDPOStableDiffusionPipeline(
+            pretrained_model, pretrained_model_revision=pretrained_revision, use_lora=True
+        )
+
+        self.trainer = AlignPropTrainer(self.alignprop_config, scorer_function, prompt_function, pipeline)
+
+        return super().setUp()

trl/__init__.py

@@ -4,6 +4,7 @@
 
 from typing import TYPE_CHECKING
 from .import_utils import _LazyModule, is_diffusers_available, OptionalDependencyNotAvailable
+import torch.utils.checkpoint as checkpoint
 
 _import_structure = {
     "core": [
@@ -39,6 +40,8 @@
         "DPOTrainer",
         "CPOConfig",
         "CPOTrainer",
+        "AlignPropConfig",
+        "AlignPropTrainer",
         "IterativeSFTTrainer",
         "KTOConfig",
         "KTOTrainer",
@@ -105,6 +108,8 @@
         DPOTrainer,
         CPOConfig,
         CPOTrainer,
+        AlignPropConfig,
+        AlignPropTrainer,
         IterativeSFTTrainer,
         KTOConfig,
         KTOTrainer,