[Feature] Support denoising demo

demo/ddpm_demo.py

@@ -0,0 +1,155 @@
+import argparse
+import os
+import os.path as osp
+import sys
+
+import mmcv
+import numpy as np
+import torch
+from mmcv import DictAction
+from torchvision import utils
+
+# yapf: disable
+sys.path.append(os.path.abspath(os.path.join(__file__, '../..')))  # isort:skip  # noqa
+
+from mmgen.apis import init_model, sample_ddpm_model  # isort:skip  # noqa
+# yapf: enable
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(description='DDPM demo')
+    parser.add_argument('config', help='test config file path')
+    parser.add_argument('checkpoint', help='checkpoint file')
+    parser.add_argument(
+        '--save-path',
+        type=str,
+        default='./work_dirs/demos/ddpm_samples.png',
+        help='path to save uncoditional samples')
+    parser.add_argument(
+        '--device', type=str, default='cuda:0', help='CUDA device id')
+
+    # args for inference/sampling
+    parser.add_argument(
+        '--num-batches', type=int, default=4, help='Batch size in inference')
+    parser.add_argument(
+        '--num-samples',
+        type=int,
+        default=12,
+        help='The total number of samples')
+    parser.add_argument(
+        '--sample-model',
+        type=str,
+        default='ema',
+        help='Which model to use for sampling')
+    parser.add_argument(
+        '--sample-cfg',
+        nargs='+',
+        action=DictAction,
+        help='Other customized kwargs for sampling function')
+    parser.add_argument(
+        '--same-noise',
+        action='store_true',
+        help='whether use same noise as input (x_T)')
+    parser.add_argument(
+        '--n-skip',
+        type=int,
+        default=25,
+        help=('Skip how many steps before selecting one to visualize. This is '
+              'helpful with denoising timestep is too much. Only work with '
+              '`save-path` is end with \'.gif\'.'))
+
+    # args for image grid
+    parser.add_argument(
+        '--padding', type=int, default=0, help='Padding in the image grid.')
+    parser.add_argument(
+        '--nrow',
+        type=int,
+        default=2,
+        help=('Number of images displayed in each row of the grid. '
+              'This argument would work only when label is not given.'))
+
+    # args for image channel order
+    parser.add_argument(
+        '--is-rgb',
+        action='store_true',
+        help=('If true, color channels will not be permuted, This option is '
+              'useful when inference model trained with rgb images.'))
+
+    args = parser.parse_args()
+    return args
+
+
+def create_gif(results, gif_name, fps=60, n_skip=1):
+    """Create gif through imageio.
+
+    Args:
+        frames (torch.Tensor): Image frames, shape like [bz, 3, H, W].
+        gif_name (str): Saved gif name.
+        fps (int, optional): Frames per second of the generated gif.
+            Defaults to 60.
+        n_skip (int, optional): Skip how many steps before selecting one to
+            visualize. Defaults to 1.
+    """
+    try:
+        import imageio
+    except ImportError:
+        raise RuntimeError('imageio is not installed,'
+                           'Please use “pip install imageio” to install')
+    frames_list = []
+    for frame in results[::n_skip]:
+        frames_list.append(
+            (frame.permute(1, 2, 0).cpu().numpy() * 255.).astype(np.uint8))
+
+    # ensure the final denoising results in frames_list
+    if not (len(results) % n_skip == 0):
+        frames_list.append((results[-1].permute(1, 2, 0).cpu().numpy() *
+                            255.).astype(np.uint8))
+
+    imageio.mimsave(gif_name, frames_list, 'GIF', fps=fps)
+
+
+def main():
+    args = parse_args()
+    model = init_model(
+        args.config, checkpoint=args.checkpoint, device=args.device)
+
+    if args.sample_cfg is None:
+        args.sample_cfg = dict()
+
+    suffix = osp.splitext(args.save_path)[-1]
+    if suffix == '.gif':
+        args.sample_cfg['save_intermedia'] = True
+
+    results = sample_ddpm_model(model, args.num_samples, args.num_batches,
+                                args.sample_model, args.same_noise,
+                                **args.sample_cfg)
+
+    # save images
+    mmcv.mkdir_or_exist(os.path.dirname(args.save_path))
+    if suffix == '.gif':
+        # concentrate all output of each timestep
+        results_timestep_list = []
+        for t in results.keys():
+            # make grid
+            results_timestep = utils.make_grid(
+                results[t], nrow=args.nrow, padding=args.padding)
+            # unsqueeze at 0, because make grid output is size like [H', W', 3]
+            results_timestep_list.append(results_timestep[None, ...])
+
+        # Concatenates to [n_timesteps, H', W', 3]
+        results_timestep = torch.cat(results_timestep_list, dim=0)
+        if not args.is_rgb:
+            results_timestep = results_timestep[:, [2, 1, 0]]
+        results_timestep = (results_timestep + 1.) / 2.
+        create_gif(results_timestep, args.save_path, n_skip=args.n_skip)
+    else:
+        if not args.is_rgb:
+            results = results[:, [2, 1, 0]]
+
+        results = (results + 1.) / 2.
+        utils.save_image(
+            results, args.save_path, nrow=args.nrow, padding=args.padding)
+
+
+if __name__ == '__main__':
+    main()

mmgen/apis/__init__.py

@@ -1,9 +1,11 @@
 # Copyright (c) OpenMMLab. All rights reserved.
 from .inference import (init_model, sample_conditional_model,
-                        sample_img2img_model, sample_uncoditional_model)
+                        sample_ddpm_model, sample_img2img_model,
+                        sample_uncoditional_model)
 from .train import set_random_seed, train_model
 
 __all__ = [
     'set_random_seed', 'train_model', 'init_model', 'sample_img2img_model',
-    'sample_uncoditional_model', 'sample_conditional_model'
+    'sample_uncoditional_model', 'sample_conditional_model',
+    'sample_ddpm_model'
 ]

mmgen/apis/inference.py

@@ -227,3 +227,71 @@ def sample_img2img_model(model, image_path, target_domain=None, **kwargs):
             **kwargs)
     output = results['target']
     return output
+
+
+@torch.no_grad()
+def sample_ddpm_model(model,
+                      num_samples=16,
+                      num_batches=4,
+                      sample_model='ema',
+                      same_noise=False,
+                      **kwargs):
+    """Sampling from ddpm models.
+
+    Args:
+        model (nn.Module): DDPM models in MMGeneration.
+        num_samples (int, optional): The total number of samples.
+            Defaults to 16.
+        num_batches (int, optional): The number of batch size for inference.
+            Defaults to 4.
+        sample_model (str, optional): Which model you want to use. ['ema',
+            'orig']. Defaults to 'ema'.
+        noise_batch (torch.Tensor): Noise batch used as denoising starting up.
+            Defaults to None.
+
+    Returns:
+        list[Tensor | dict]: Generated image tensor.
+    """
+    model.eval()
+
+    n_repeat = num_samples // num_batches
+    batches_list = [num_batches] * n_repeat
+
+    if num_samples % num_batches > 0:
+        batches_list.append(num_samples % num_batches)
+
+    noise_batch = torch.randn(model.image_shape) if same_noise else None
+
+    res_list = []
+    # inference
+    for idx, batches in enumerate(batches_list):
+        mmcv.print_log(
+            f'Start to sample batch [{idx+1} / '
+            f'{len(batches_list)}]', 'mmgen')
+        noise_batch_ = noise_batch[None, ...].expand(batches, -1, -1, -1) \
+            if same_noise else None
+
+        res = model.sample_from_noise(
+            noise_batch_,
+            num_batches=batches,
+            sample_model=sample_model,
+            show_pbar=True,
+            **kwargs)
+        if isinstance(res, dict):
+            res = {k: v.cpu() for k, v in res.items()}
+        elif isinstance(res, torch.Tensor):
+            res = res.cpu()
+        else:
+            raise ValueError('Sample results should be \'dict\' or '
+                             f'\'torch.Tensor\', but receive \'{type(res)}\'')
+        res_list.append(res)
+
+    # gather the res_list
+    if isinstance(res_list[0], dict):
+        res_dict = dict()
+        for t in res_list[0].keys():
+            # num_samples x 3 x H x W
+            res_dict[t] = torch.cat([res[t] for res in res_list], dim=0)
+        return res_dict
+    else:
+        return torch.cat(res_list, dim=0)

tests/test_apis/test_inference.py

@@ -4,7 +4,7 @@
 import pytest
 import torch
 
-from mmgen.apis import (init_model, sample_img2img_model,
+from mmgen.apis import (init_model, sample_ddpm_model, sample_img2img_model,
                         sample_uncoditional_model)
 
 
@@ -78,3 +78,52 @@ def test_translation_model_cuda(self):
         res = sample_img2img_model(
             self.cyclegan.cuda(), self.img_path, target_domain='photo')
         assert res.shape == (1, 3, 256, 256)
+
+
+class TestDiffusionModel:
+
+    @classmethod
+    def setup_class(cls):
+        project_dir = os.path.abspath(os.path.join(__file__, '../../..'))
+        ddpm_config = mmcv.Config.fromfile(
+            os.path.join(
+                project_dir, 'configs/improved_ddpm/'
+                'ddpm_cosine_hybird_timestep-4k_drop0.3_'
+                'cifar10_32x32_b8x16_500k.py'))
+        # change timesteps to speed up test process
+        ddpm_config.model['num_timesteps'] = 10
+        cls.model = init_model(ddpm_config, checkpoint=None, device='cpu')
+
+    def test_diffusion_model_cpu(self):
+        # save_intermedia is False
+        res = sample_ddpm_model(
+            self.model, num_samples=3, num_batches=2, same_noise=True)
+        assert res.shape == (3, 3, 32, 32)
+
+        # save_intermedia is True
+        res = sample_ddpm_model(
+            self.model,
+            num_samples=2,
+            num_batches=2,
+            same_noise=True,
+            save_intermedia=True)
+        assert isinstance(res, dict)
+        assert all([i in res for i in range(10)])
+
+    @pytest.mark.skipif(not torch.cuda.is_available(), reason='requires cuda')
+    def test_diffusion_model_cuda(self):
+        model = self.model.cuda()
+        # save_intermedia is False
+        res = sample_ddpm_model(
+            model, num_samples=3, num_batches=2, same_noise=True)
+        assert res.shape == (3, 3, 32, 32)
+
+        # save_intermedia is True
+        res = sample_ddpm_model(
+            model,
+            num_samples=2,
+            num_batches=2,
+            same_noise=True,
+            save_intermedia=True)
+        assert isinstance(res, dict)
+        assert all([i in res for i in range(10)])